Foliar feeding refers to feeding plants by spraying nutrients on leaves and fruit.
Normally, plants absorb their mineral nutrients from the surrounding soil through the root system. Nutrients can also be absorbed through the stomata, tiny holes used for gas and moisture regulation, found on leaves and fruit.
Foliar feeding claims
Advertisements claim that foliar feeding is many times more efficient than soil feeding, that it cannot be used incorrectly, it promotes larger, sweeter crops, boosts a plant’s tolerance for heat and cold, increases pest and disease resistance, and even improves a plant’s internal circulation. Wouldn’t that be something? The number and diversity of these claims should raise a warning flag, and with good reason. Most of the claims about foliar feeding are false, but there are situations where foliar feeding is useful.
Foliar feeding research
The claims made about foliar feeding are based on research published in 1957 in which leaves and fruit were shown to be very efficient at absorbing tiny amounts of mineral nutrients in a lab setting. You can read the full report here.
Unlike nutrients absorbed through the root system and transported through the xylem, nutrients absorbed through leaf stomata are more likely to remain in nearby plant tissue. This is especially true for the ‘immobile’ nutrients, such as calcium and magnesium. According to the study, “Phosphorus, choline, sulfur, zinc, copper, manganese, iron, and molybdenum were intermediate [with regards to absorption] with decreasing mobility in the order given.” Potassium and sodium were shown to be the most readily absorbed and highly mobile nutrients.
Again, this research was conducted under laboratory conditions, not out in someone’s garden. As one might expect, results are very different in the field. There are, however, some cases where foliar feeding is a good thing.
Foliar feeding and alkaline soil
Nutrient absorption is helped or hindered by soil chemistry and electrical charges in the soil. One aspect of that chemistry is soil pH. Acidic soil has a pH of less than 7.0 and alkaline soil has a pH greater than 7.0. This is important because alkaline soil is slower to release metallic nutrients, such as iron and manganese. If your soil is deficient in these nutrients, foliar feeding can help in the short-term while you make long-term adjustments to your soil.
The downside to foliar feeding
Simply spraying fertilizer on your plants’ leaves is a good way to burn them. There are too many variables to make foliar feeding something you would want to do all the time with all your plants. Environmental conditions, species characteristics, developmental stages of the plants, varying thicknesses of plant cuticles, and the likelihood of stomata being open or not all contribute to a lot of wasted fertilizer and the potential for harm.
Foliar feeding case in point
For those of you who have been reading The Daily Garden for a while now, you may recall reading about how my first soil test, in 2015, reported extraordinary numbers for all nutrients except iron. This was due to over-fertilizing done by the previous owner. That imbalance made those abundant nutrients largely unavailable to my plants. Also, my soil pH at that time was 7.7 and the soil was badly compacted. Truth be told, it looked and felt like concrete.
At that time, nearly all the plants in my landscape were being damaged by fungal diseases (partly due to badly aimed sprinklers), aphids, borers, scale insects, and what looked like nutrient deficiencies. Of course, the automatic (and incorrect) response would have been to add more fertilizer. Thanks to my lab-based soil test, I had the information I needed to make better decisions.
If you have fruit and nut trees, you can prune those trees to improve both the quantity and quality of your crop, or you might eliminate production altogether.
Normal annual pruning involves removing dead, diseased, and rubbing branches. It also means training trees for shape, size, structure, and air flow. This is normally done while trees are dormant, in winter. There is also renewal pruning, done in autumn, which stimulates new growth the following spring. But, did you know that you can also prune for better fruit production? It’s true!
How fruit happens
Fruit and nut trees produce buds. When those buds are fertilized, they can grow into fruit or nuts. [Assuming the tree of healthy enough and old enough.] But some trees produce fruit on new growth, while others produce fruit on old growth. If you keep cutting off productive wood, you won’t have much of a crop.
Where do trees produce fruit?
Depending on the species, trees produce fruit either on long shoots or on stubby spurs. That fruit can be arranged laterally, along the sides, or at the terminal end. Take a look at the chart below for information about your trees.
This may seem like too much information to be useful, but let’s walk through a few examples together, so you can see how to better prune your trees.
You can see that almond trees produce the majority of their fruit on lateral spurs, and some fruit along lateral shoots. You will also see that each spur is good for 5 years, that very little pruning is needed, and that almond trees are best trained in the open center system. So, what does all this mean to the owner of an almond tree?
First, snipping the tips off of anything on an almond tree won’t harm nut production. Of course, if you snip too much, the tree will have to put energy into healing, rather than filling your hopper with delicious almonds. The open center system is exactly what it sounds like - the center of the tree is left clear of major branches in the middle, creating a bowl shape which allows for plenty of sunlight and air to move through.
Looking at the information for apples, you can see that snipping off the ends of all the spurs would leave you without much of an apple crop, but cutting off the ends of long shoots would only have a very slight impact.
Now look at persimmons. All of the fruit production occurs on long shoots of new wood. Cutting out all of your new growth would hamper fruit production. The same is true for quince. Figs are produced on new wood and one-year old shoots.
Generally speaking, citrus trees do not need to be pruned to improve fruit production.
If you sort the chart by location of major fruiting buds, you have:
Armed with this information, go outside, sanitized pruners in hand, and see where you can prune your fruit and nut trees for improved overall health and a significant increase in production!
They will never jump through a hoop for you, but you can train your trees to be healthier and more productive.
Tree training helps fruit and nut trees stay healthy, produce larger crops, and avoid broken branches. Proper tree training also reduces the likelihood of pests and disease. Too much fruit and strong winds can result in broken branches. Proper training can prevent these problems. You may not want to go as far as pollarding or coppicing, but training your trees for good structure, air flow, and the retention of productive wood is always a good idea, except when it isn’t. Trees that are particularly large or unstable should never be trimmed or pruned by an amateur. It is too dangerous.
When to train trees
Most fruit and nut trees are deciduous. This means they go dormant and lose their leaves in winter. This is handy for several reasons. First, it allows you to remove leaves that may be carrying pests or diseases. Secondly, it allows you to see the true structure of your trees. This makes training them a lot easier. The only exceptions are cherry and apricot trees, which should only be pruned in summer, to avoid Eutypa dieback.
Making a proper cut
You may want to read up on pruning before you start training your trees. Put simply, you will want to make a smooth cut that is flush with, but does not cut into, the branch collar. There is no need to paint or treat these cuts. Your tree will develop a protective callus over the area, all on its own.
Tree training basics
To maintain a healthy fruit or nut tree in your backyard, you will probably want to keep it pruned to a manageable size. This is usually 6 feet tall and 6 feet wide. If it gets too large, you won’t be able to reach. Surprisingly, trees of this size can still produce a lot of fruit. As with any other pruning job, you will want to remove any dead, diseased, or damaged limbs. You will also want to eliminate one of any pair of crossed branches. These will tend to rub against each other, creating points of entry for pests and disease. As you prune, try to work from the inside out and avoid leaving stubs. You can orchestrate the direction new twigs will take by cutting just above buds that face in the direction you want the new twigs to grow. Do not use downward facing buds as these tend to be weak and break easily. Your overall goal should be to expose the tree’s interior to more sunlight, without risking extensive sunburn damage.
The big picture
Before cutting, take the time to really look at your tree’s structure and shape. Learn what is typical for that particular species, and think about what you want from your tree over the next several years. Consider issues such as wind exposure, shifting shade patterns, fruit and leaf litter, and tree maintenance. What is proper training for a tree in one location may be completely inappropriate in a different location. If you’re not sure, ask me. You can also look at this fruiting wood characteristics chart, from UC Davis, that can help you decide what to remove and what to leave for another year. Once you have really looked at your tree and prepared your tools, you will need to select the training style best suited to your tree species. The lowest branches are usually at knee height, regardless of the style chosen.
The central leader training style is best suited to semi-dwarf and standard size trees. This style features a single main, vertical trunk. Competing upright shoots are removed and an alternating spiral of lateral branches is encouraged. This is your classic Christmas tree shape.
Modified central leader
The modified central leader style allows more sunlight into the center than a central leader system. To create this shape, a tree is first trained as a central leader, until it reaches the desired height. Then, the central trunk is topped, or removed, just above the most recent lateral growth. This causes the tree to develop more of an open center. This method is particularly good for cherries and pears.
The open center style seems to be the most popular for backyard orchards. In this style, three or four low-growing scaffold (main) branches are encouraged, with the center kept open, like a bowl. Lateral (horizontal) branches make up the sides of this bowl shape and are trimmed back to approximately 30 inches. Fruiting wood will grow from these branches. This method provides good sun exposure and air flow. Also known as vase-shaped training, it is a good method for almonds, Asian pears, and European plums.
The “Y” system
The “Y” system features two scaffolding branches, heading in opposite directions, creating a “Y” shape. Look at it as a two-dimensional open center style. This method is particularly good for peaches and nectarines. It can also be used for apples, plums, cherries, and pears.
Espalier training is a trellising system used to create a two dimensional shape. This method works well alongside driveways, paths, buildings, and fences.
If you end up removing smaller, new wood, you can save these and use them as scions, to create new trees or modify existing trees. They make good gifts for fellow gardeners, as well!
Also, as you work closely with your tree, keep a look out for scale and other insect pests that may be overwintering in your tree’s bark.
Secondary plant nutrients are calcium (Ca), magnesium (Mg), and sulfur (S).
The nutrients plants use the most are called primary nutrients. Nitrogen, potassium, and phosphorus are primary nutrients. On the other hand, only tiny amounts of boron, copper, iron, chloride, manganese, molybdenum, and zinc are needed. These micronutrients used to be called trace elements. In the middle are the secondary nutrients. Secondary nutrients rarely need to be supplemented, but they are very important to plant health.
Most soils already contain high enough levels of these secondary nutrients, but you don’t know for sure without a lab-based soil test. The effects of not enough or too much of any one nutrient can create a domino effect that is difficult to diagnose. Simply adding more fertilizer can often makes problems worse, rather than better.
Why are these secondary nutrients important and what are some signs of toxicity or deficiency? Let’s find out!
Plants use calcium to build strong cell walls, to move materials across cell membranes, to grow primary root systems, and to maintain the cation-anion balance. [Cations and anions are electrically charged atoms of minerals that plants use for food.] Optimal levels of calcium range from 1000 to 1500 parts per million (ppm).
Calcium is relatively immobile inside a plant. It takes a lot of water to move a calcium molecule around inside a plant. That’s why blossom end rot is more of an irrigation problem than a calcium deficiency problem. Calcium deficiencies, whether caused by real lack or insufficient irrigation, are rare in nature. When they do occur, they can cause bitter pit in apples, cavity spot in carrots, and leaf tip burn in several different plants.
Too much calcium is also rare, but it can interfere with the absorption of magnesium and potassium, causing deficiencies in those nutrients. Bottom line with calcium: irrigate adequately, regularly and consistently.
Magnesium is essential for plant health. Ideal levels of magnesium range from 50 to 120 ppm. Magnesium stabilizes cell membranes, making plants better able to withstand drought and sunburn. Magnesium is found in enzymes that plants use to metabolize carbohydrates. Most important, magnesium is contained in the chlorophyll molecules that convert the sun’s energy into food. This process, the Calvin Cycle, is what makes photosynthesis possible.
Too much magnesium in the soil makes it difficult for plants to absorb calcium and other nutrients, which can lead to blossom end rot, bronzing, and many other problems. This is a common problem in areas with alkaline soil. The opposite is true in areas with acidic soil.
Insufficient magnesium symptoms look like potassium toxicity symptoms. Older leaves, at the bottom of the plant, start turning brown, between and alongside the leaf veins, working upward through the plant. Magnesium deficiencies in stone fruits often start out as slightly brown areas along leaf edges (margins) that expand inward, causing cracking, necrosis, and leaf loss. Magnesium deficiency in California is extremely rare.
Plants use a surprising amount of sulfur. This secondary nutrient is used in making chlorophyll and certain proteins and enzymes. Sulfur is also part of the arrangement between legumes and rhizobia bacteria that allow them to make use of atmospheric nitrogen.
Sulfur deficiency is seen first in new growth. Leaves are pale and growth is spindly. If sulfur levels become toxic, leaves will be smaller than normal and have scorched edges. Sulfur is commonly used as an organic fungicide and to acidify the soil.
Do not use horticultural oil within 2-4 weeks of applying sulfur. Sulfur and horticultural oil are phytotoxic (poisonous to plants) when combined. Also, it is better to use fixed copper, rather than sulfur, on apricot trees.
Your plants may not need as much of these secondary nutrients, but they are just as important to plant health. Get a lab-based soil test to find out what is in your soil.
Irrigation is what makes agriculture possible.
The history of irrigation
Humans started irrigating crops (on purpose) as far back as 6,000 B.C. Those early efforts were nothing more than redirecting the flows of the Nile and Tigris Rivers in Egypt and Mesopotamia. Twenty-five hundred years later, irrigation science led to the invention of the Nilometer. The Nilometer was generally a stick, or some stairs, that went down into the river to measure its changing depth. Priests would use that information to ‘magically’ predict the next flood. Another 400 years would pass before anyone thought to build actual canals and dams to redirect water into agricultural fields. It would take another thousand years before the Romans figured out concrete pipes. In fact, we owe a debt of gratitude to those same Romans for inventing indoor plumbing - yay! Two hundred and fifty years later, Hammurabi (the man responsible for the first set of written laws) instituted water regulations. Some of Hammurabi’s water regulations include:
55. If any one open his ditches to water his crop, but is careless, and the water flood the field of his neighbor, then he shall pay his neighbor corn for his loss.
56. If a man let in the water, and the water overflow the plantation of his neighbor, he shall pay ten gur of corn for every ten gan of land.
I have no idea what ‘gurs’ or ‘gans’ are, but you get the idea - we’ve been fighting over water rights for a really long time!
Good water management
Many years ago, while living in an RV and traveling the country, I stopped at a midwestern diner in the wee hours of the morning for some breakfast. The old men who filled the booths and sat at the counter had but one topic of conversation: rain. They were comparing notes on how many hundredths of an inch fell on their respective properties. It was not what I expected, but it made me realize how much science there is behind irrigating crops properly. Good water management means understanding the necessary timing, volume, and application method best suited to your garden and landscape plants.
Farmers deal with irrigation water in terms of acre-feet. One acre-foot refers to how much water is needed to cover one acre of land (43,560 sq. ft.) to a depth of one cubic foot. If you do the math, that ends up being 325,851 gallons of water! Per acre. Each week. You see why drought is such a Big Deal in the world of agriculture! Now, as home gardeners, we will never be using water at those rates. Instead, we have to look at our garden spaces as micro versions of the same calculations. Instead of acre-feet, we need to look at square feet.
How much water does my plant need?
One of the most common gardening questions asked is: How much water does my favorite garden plant need? And the answer is always: It depends. [This invariably irritates some people, but it’s the truth.] Water needs are a function of too many variables to give a pat answer. Soil structure and makeup, plant variety, microclimate, stage of development, life stage process, plant size, root depth*, and exposure to heat islands are just a few of those variables. In California, UC Davis recommends one inch of water each week during the peak of summer. To fill a one foot by one foot area with water to a depth of 1 inch uses 0.623 gallons.
For example, let’s say you have a 4’ by 6’ raised bed:
4 * 6 = 24 sq. ft.
24 * 0.623 = 14.952 gallons
Your raised bed should receive 15 gallons of water during the peak of summer. In spring and fall, half that amount should suffice. Now, if you dump 15 gallons of water into that raised bed all at once, most of it will percolate down through the soil and disappear from the plants’ root zone*. It is far better to water every day during summer. This would mean adding a little more than 2 gallons to our example bed each day of summer.
* How deep do garden plant roots go?
Rooting depth changes, depending on the variables mentioned earlier, but you can use the information below from UC Davis for a general idea for mature, full-sized plants:
How to irrigate
You have several options when it comes to how you get the water to your plants. You can spray with a hose, use sprinklers, fill furrows, use soaker hoses, or install drip emitters. Each method has its pros and cons:
In each case, you will need to know how much water is being delivered. If your bed needs 2 gallons of water a day and you have a 2-gallon watering can, well, there you go. If you are using any other method, you will need to know how much water is coming out of the spigot. You can buy a gadget that is installed between the spigot and the hose for the easiest calculation, just be sure to avoid the cheap, plastic models. They are inaccurate and break very quickly. Also, you need to know that just because you applied the water does not mean it went where you intended. Soil can do funny things to water underground. Take the time to gently dig around plant roots after irrigating to see that the water actually saturated the root zone, rather than running off someplace else.
Irrigating compacted clay soil
Here in the Bay Area, we have heavy clay soil that is often compacted. That means we must be careful when irrigating. Irrigating compacted or clay soil too heavily simply compounds existing problems. Water slowly and gently, and do not dig or till wet soil. The smooth edges left behind can harden into an impenetrable barrier for tender roots.
Benefits of proper irrigation
Not only will plants receive the correct amount of water as they grow, but less water is wasted, pests and diseases are minimized, and plants will be more likely to reach their full potential. You can simplify irrigation by grouping plants with similar water needs.
When it comes to container plants, you generally need to give them more water than in-ground plants. Self-watering containers are an easy way to make sure that your container plants have the water they need.
Calcium is a critical plant nutrient commonly found in alkaline soil. But that doesn’t mean your plants can get to it. And it doesn’t look the way you probably expect.
Calcium inside plants
We all know that calcium makes for strong bones and teeth. It also helps plants stay healthy. In fact, calcium is critical to plant growth and development. Plants use calcium to build strong cell walls, to move materials across cell membranes, to grow primary root systems, and to maintain the cation-anion balance. [Cations and anions are electrically charged atoms of minerals that plants use for food.]
Researchers learned, in 2016, that the movement of calcium molecules in plant root cells triggers proteins that tell the plant that nitrogen-fixing bacteria are nearby. This causes the plant to start building nodules on the roots that will serve as homes to those helpful bacteria. Bottom line, as calcium walks in the door, the welcome mat for nitrogen-fixing bacteria gets unrolled, setting the stage for healthier and more productive plants. [This stuff amazes me.]
Calcium deficiency is often caused by irregular irrigation. Unlike more mobile nutrients, such as nitrogen, calcium does not move around within a plant easily. Once it stops traveling through the xylem, it pretty much stays where it is. This is why calcium deficiency is rarely seen in older plant tissue. Normally, calcium is moved through a plant by evapotranspiration, which uses a lot of water. Calcium deficiency can also occur when there is too much nitrogen in the soil, causing plants to grow faster than they can move the available calcium. When plants do not have enough calcium, you may see stunted growth, leaf curling, dead terminal buds and root tips, leaves with brown spots along the edges that spread toward the center. These damaged areas make it easier for pests and disease to strike. Some crop-specific symptoms of calcium deficiency include:
Drought and minerals
Minerals, such as calcium, are affected by drought in ways that might surprise you. Reduced water supplies often mean we get our tap (irrigation) water from reservoirs that are scraping the bottom of the proverbial barrel. That water already has high salt and mineral contents. The chemical reactions that occur between those salts and plant nutrients can make life difficult for everyone involved.
California pistachio growers have found that, by adding more calcium to the soil, they can reduce the amount of salt absorbed by plants. This is not something you should attempt in your garden, because what you just read is an oversimplification of a complex condition. I only use it to point out the amazing balancing act that is going on all the time to get you the foods you love. Another factor that involves drought and calcium is drip irrigation emitters. They tend to get clogged by calcium the same way your coffee maker and iron do. If your region has hard (high mineral content) water, you may want to invest in a filter.
Sources of calcium
Before adding calcium to your soil, it is important to find out what it already contains. Most San Jose soils contain abundant calcium. The optimal range is 1000-1500 ppm. My laboratory soil test results for calcium were 2705 ppm in 2015 and 2586 ppm in 2019! A soil test, conducted by a reputable lab, is the only way to know for sure. Over-the-counter soil tests are not reliable or accurate enough. If you are growing in San Jose, California (or anywhere there used to be an ocean), there’s probably plenty of calcium already present. If you live east of the Rockies, it’s a different story. Agricultural lime and calcium chloride sprays can be used to replenish depleted soils. Sorry, but egg shells do not add calcium to your soil.
Calcium uptake problems
Let’s assume that your soil has plenty of calcium in it. and that you are watering regularly and properly. There are other problems that can interfere with a plant’s ability to absorb this important nutrient. Excessive potassium (K) is one. Too much magnesium (Mg), sodium (Na), iron (Fe), or ammonium (NH4+) can also slow the uptake of calcium. Soil alkalinity or acidity (pH) also plays a role.
The molecular balancing act that occurs between minerals within your soil and plants is mind-boggling, to say the least. Suffice to say, your average gardener (or gardening blogger) only groks the tip of this iceberg. This is not something to guess about. Get your soil tested. Your plants will thank you.
Organic gardening and farming are on the rise. But what does ‘organic’ really mean? Let’s find out.
The word ‘organic’ simply means that something is made from materials that were, at one point, alive.
The term ‘organic food’ means different things in different countries. In some countries, it means absolutely nothing. In the United States, it refers to food produced by certified organic farming methods. Certified organic farming uses the following practices:
In a perfect world, organic foods (and clothing) would be exactly that, but we don’t, so it isn’t. Car fumes, GMO pollen, reckless profiteering, and countless other inputs make purely organic farming an impossibility. It is, however, still worth aiming for.
Organic pesticides and fertilizers
Many organic farmers still spray crops with chemical pesticides and fertilizers, it’s just that the chemicals they use must be from natural sources, and they must be dispensed using equipment that was not used with synthetic chemicals. That being said, some of the ‘natural chemicals’ used in organic farming are pretty awful. Just because something occurs naturally doesn’t mean it’s safe to eat. Death cap mushrooms are a perfect example. Also, good intentions are not always enough. Horse and cow manure are excellent for composting, but are you certain about which medications, diseases, or other ingredients might come along with that manure? Good cultural practices, garden sanitation, biodiversity, and composting can all help reduce the need for any type of chemicals in your garden or landscape.
Mulch is an excellent way to protect unplanted areas, but where did it come from and what is in it? Mulch from tree trimmers is usually a good bet (and free!), but there is still no guarantee that the trees weren’t diseased or sprayed with chemicals. Even worse, mulch made from discarded lumber may contain arsenic. Yikes! You can use your own yard waste to create a relatively organic mulch and reduce landfills as the same time.
Organic potting and planting soil
Deciding to grow your own food isn’t as simple as it sounds, either. Does your bag of potting soil contain ground up car tires? What about styrofoam? Just because a bag of soil says ‘natural’ or ‘organic’ does not mean it is healthy for you or your plants. If you want truly organic, you must look for the certified OMRI (Organic Materials Review Institute) label.
Sometimes we think we’re doing the right thing and it ends up being the wrong thing. For example, if you bought birdseed from 2005 to 2008, you may have been party to poisoning the very birds you were trying to help! Scotts Miracle-Gro knowingly sold birdseed tainted with chemicals toxic to birds, fish, and other wildlife. Would using organic birdseed have been better? Probably. [Personally, I won’t be buying ANYTHING* from Scotts Miracle-Gro. EVER.]
Before despair sets in, let’s turn around and look at the positive side of things. As I said at the beginning, organic farming and organic agriculture are on the rise. Sales of organic foods and textiles are also increasing. As more certified organic farms become established, the prices of organic foods drops, making them affordable for more people. That’s all really good news. Also, for every food item that you grow for yourself, you will have a far better idea what went into that plant before you eat it.
In the world of organic gardening and farming, the bottom line is: who do you trust with your family’s health?
* Scotts Miracle-Gro sells the following product lines: Scotts, Miracle-Gro, Ortho, RoundUp, Tomcat, nature’s care. Osmocote, Substral, Evergreen, Nexa, Celaflor, KB, Fertiligene, Naturen, Weedol, Earthgro, and Hyponex, just so you know what I won’t be buying. What you do is up to you.
Soaker hoses are an inexpensive way to add a drip-system to your garden or landscape.
While many gardening aficionados dream of The Perfect Drip System, most of us have neither the time or the money to do so. Also, drip emitters can clog and they require regular monitoring and maintenance. Hm, maybe they’re not so perfect after all, eh? Soaker hoses give similar results for far less money.
How do soaker hoses work?
Soaker hoses look just like other garden hoses, except they have thousands of tiny holes, or pores, in them. These holes allow irrigation water to slowly ooze out, along the length of the hose, dripping water where your plants need it most.
I know that many of us enjoy a certain sense of tranquility, strolling through the garden, hose in hand, dispensing life-giving water as we go. Unfortunately, hand watering isn’t nearly as efficient as we would like to think. [Next time you hand water, take a trowel to the area and see just how much water actually made it to a root zone.] Also, overhead watering increases the chance of many fungal diseases.
Benefits of watering with a soaker hose
A well designed watering system can use 30 to 50% less water and get better results. Other benefits of watering with a soaker hose include:
Choosing the right soaker hose
Like most garden hoses, the majority of soaker hoses currently available contain lead and other potentially toxic chemicals. Many of them are made from ground up old car tires, which doesn’t strike me as very appetizing. While they do cost more, I use food-grade hoses in my garden. Food grade garden hoses are becoming more readily available and prices are slowly coming down as they sell enough of them to cover their costs and make a decent living. They even come in pretty colors! You can find soaker hoses with built in pressure valves and quick-release connectors. You can also find soaker hose systems that allow you to connect segments of soaker hose with segments of regular garden hose for more control. Again, make sure that the materials used are durable and food-grade before you use it to water your tomatoes.
How and where to use soaker hoses
Soaker hoses are generally left in place for the growing season. Snake your soaker hose through your vegetable garden, looping around fruit and nut trees, or among your ornamentals. Soaker hoses are an excellent addition to raised beds and straw bale gardens. These tips will help you get the best results from your soaker hose:
Leave soaker hoses running until the water has saturated your plants’ root zones. Since each plant is different, you really should use a trowel to see where the roots are and how deep the water is going. Monitor how long it takes for that much watering to occur, and then you can add a timer to your faucet for added convenience. Just remember that as temperatures rise and plants grow, they will need more water.
It is a good idea to flush out soaker hoses a couple of times a year. To do this, simply take the end cap off and turn the water on. It only takes a minute or two. Then be sure to put the end cap back on!
Invest in food grade garden and soaker hoses for better water efficiency and healthy plants.
As fruit trees begin putting out fruit in spring, it is your job to take some of that fruit off.
It may seem counterproductive. Why on earth would I plant a fruit tree only to take the fruit off when it has only just started growing? Why would you want to reduce your crop that way? Read on and find out!
Why thin fruit?
Most fruit trees will produce far more fruit than can be supported or made flavorful. Too much fruit and branches start breaking. Now, the tree doesn’t care how the fruit tastes, as long as it tastes good enough to cause animals to help with seed dispersal. To get the sweetness, size, and shape that we want, we have to intervene. Thinning fruit also helps reduce the likelihood of pests or diseases getting established in the nooks and crannies between fruit. Finally, fruit thinning reduces the chance of your tree taking a year off of production (alternate bearing) out of sheer exhaustion.
How (and when) to thin fruit trees
Different trees have different thinning needs. Generally, the time to thin fruit is dictated by fruit size. Stone fruits are thinned when they reach 3/4 to 1 inch in diameter, while pome fruits can be thinned when they are 1/2 to 1 inch. This is usually in April and May in the Bay Area. You can also predict the time for thinning by noting it 30 to 45 days after full bloom on your calendar. To actually remove the fruit, give it a gentle twist. Sometimes, pruners are needed. Your fruit tree is working very hard at this stage, so be kind. Do not be tempted to thin your fruit trees too early, as this can lead to split fruit later on, especially in peaches. Of course, thinning too late won’t help your fruit become as large as it might have.
Fruit thinning by species
Some trees do not require thinning. These include cherries, figs, citrus, Bartlett pears, pomegranates, and persimmons. You may want to monitor your persimmons tree, however, as a very productive year can lead to breakage. Use this information to determine just how much to thin, depending on tree species:
Natural fruit drop
We are not the only ones who want to protect our fruit trees from breakage due to too much fruit. These trees have evolved to protect themselves with what is erroneously called “June drop”. June drop can occur late spring through early summer and it refers to a fruit tree dropping many immature fruits. Fruits that are diseased or infested may also drop prematurely.
Don’t be afraid to get up close and personal with your fruit trees in spring. Thinning fruit will ensure a better crop and a healthier tree. Thinning also gives you a chance to see what’s really going on for your fruit trees, allowing you to halt a minor pest invasion before it causes any real damage.
For those of you (like me) who need ways to remember what and how to thin, give this a try:
Spring season of thinning, no need to despair
Help them grow stronger with inches to spare
Small apricots and plums, give them each two to four
Peaches and nectarines, need three inches or more
Then muster the clusters of apples and pears
Save just the biggest, only one or two there
Mutants and mummies and twins all must go
Leave only the best. Now just watch them grow!
Insecticidal soaps are an easy DIY method of pest control in the garden.
People have been using soap sprays for a long time to protect their plants, but the science behind using soap has only begun to demonstrate just how insecticidal soaps work. Current research has shown that spraying soapy water on insects kills them off by:
Before jumping on the insecticidal soap bandwagon, however, you need to understand that not all soaps are created equally and that many soaps are actually detergents that can kill your plants.
Homemade insecticidal soaps
True insecticidal soaps contain potassium salts of fatty acids and are designed specifically for use on plants. These fatty acids are commonly found in fish oil, lard, and olive, palm, coconut and other plant oils. These fatty acids are mixed with potassium hydroxide, which is strongly alkaline, to create soap, much the way fatty acids are mixed with sodium hydroxide to make lye. While potassium salts and sodium salts will both kill insects, sodium salts are toxic to plants. [The same problem occurs when people use baking soda (sodium bicarbonate), rather than potassium bicarbonate, on plants to fight fungal disease. Baking soda is phytotoxic, whereas potassium bicarbonate is not.]
Not all household liquid soaps are safe for use on plants. In fact, I couldn’t find a list of any that are truly safe. Laundry soaps and dry dishwashing detergents are also too harsh to be used on your garden plants. Also, many liquid dishwashing soaps contain bleach, fragrances and colors, and other chemicals that can harm or kill your plants. As tempting as it may be to grab your bottle of dish soap from the kitchen sink, this is not a good idea. [I challenge you to take a close look at the ingredients list on your dishwashing soap and look up any words you don’t know.]
Effectiveness of insecticidal soap
Instead of burning up your plants with detergent, go to the store and buy a bottle of insecticidal soap. It is less expensive that many other pesticides, plus it is less damaging to the environment and other living things. Insecticidal soap that has been properly formulated and applied will kill many common pests, including:
Unfortunately, insecticidal soap can also kill off the larval forms of many beneficial insects, such as ladybugs and lacewings.
How to use insecticidal soap
Insecticidal soap only works when it comes in direct contact with and completely covers an insect pest. Use these tips to safely use insecticidal soap:
Insecticidal soaps have little or no residual effects, so treatments must be repeated regularly until the desired level of control is reached.
So, insecticidal soap isn’t the Quick Fix you might have thought it was before reading this post, but it is effective when used properly.
What happened? Yesterday, your plants looked lovely. Today, several leaves are rolled up, looking like green cigars. What did this, is it a problem, and what can you do?
Leaf roll (or leafroll) is not the newest thing in Burmese take-out. Instead, it is a symptom that can give you clues about what is going on in your garden. Leaf roll can be caused by environmental stresses , viral infections, fungal infection, pests, or herbicide damage.
If you notice leaves starting to roll on any of your plants, start by asking yourself the following questions:
Physiological or environmental causes of leafroll
Environmental or physiological damage is normally visible near the base of a plant first, as leaves cup upward, toward the leaf vein. These leaves tend to thicken and become leathery, while remaining a normal green color, as the plant tries to protect itself. Environmental damage is a common problem when growing members of the nightshade family, such as tomatoes, peppers, and eggplant. Interestingly enough, bush (determinate) varieties are less likely to exhibit leaf roll than vine (indeterminate) varieties. Symptoms of environmental damage can indicate any of these problems:
Some viral diseases can also cause leaf roll. Viruses often enter plant tissue as insect carriers feed. These carriers are normally aphids, mealybugs, and soft scale insects. Leaf roll viruses can also be spread through infected scion wood. Once infected, vascular bundles become clogged as the viruses reproduce in the nutrient-rich phloem. This reduces water and nutrient flow within the plant, causing stunting, delayed maturity, reduced crop size, chlorosis, necrosis, and leaf roll.
Viral infections affect newer leaves first. Leaves cup upwards and turn pale green. They may also have yellow edges, mottling, and veins may look purplish. This color change is due to damage to the phloem. Infected fruit may start rotting from the inside out.
There are three major types of viral leafroll that warrant concern:
Because these viruses can spread rapidly, over relatively great distances, close monitoring and control are in everyone’s best interest. Once a plant is infected with one of the leafroll viruses, it should be removed and destroyed. There is no cure or treatment. When shopping for plants, choose resistant varieties and put them in quarantine when you bring them home. Controlling carrier pests will also help reduce the likelihood of leafroll affecting your garden.
Leaf curl caused by fungal infections can be particularly destructive, since the disease can be carried in by whiteflies. Peach leaf curl, bacterial blast, and botrytis are common examples. Symptoms include:
As aphids, leaf miners, thrips, mites, scale insects, and mealybugs feed on sap, they can cause leaves to curl. Occasionally, a spider may curl a leaf to create a cocoon, but spiders are Good Guys in the garden, so leave them alone. The real pest when it comes to leaf rolling comes from the larva of certain moths. In particular, California has a problem with moths in the tortricid family. These pests can be found in citrus, pear, plum, apple, almond, apricot, raspberries and other cane fruit, quince, and walnut, plus most ornamentals. Light brown apple moths also fall in this category. Pest damage usually includes ragged edges on nearby leaves and tightly rolled nesting leaves. Inspect fruit and nut trees carefully from March through May for signs of these pests.
The ads make herbicides look so safe and helpful, but they are, in my opinion, anything but. Leaching, overspray, rain splash, a sudden breeze, and the failure to breakdown in the soil as advertised can put many other plants at risk. Symptoms of herbicide damage include:
If you notice leaf rolling on your garden or landscape plants, take a closer look to see if you can figure out what is causing this change. Knowing the cause helps you find a solution that allows your plants stay healthy and productive.
Renewal pruning is a method that stimulates new growth while removing unproductive wood or canes.
According to some, renewal pruning refers specifically to plants that produce canes from the root system. I am going to use the broader definition above. The general rule of thumb for renewal pruning is to remove one-third of any older wood each year. These are thinning cuts that take branches back to the main stem or crown, depending on the growth habit. [When making thinning cuts, be sure to avoid damaging the branch collar.] Each species has its own characteristics, which need to be taken into account before you start lopping off branches. Some of the more common approaches to renewal pruning are listed below.
Renewal pruning of currants
Currants produce fruit on spurs that emerge from 2- and 3-year old wood. After that, those limbs are far less productive. Use the following pruning schedule on currants:
Renewal pruning of fruit trees
Fruit and nut trees produce fruit on spurs and on twig tips. Some species only produce fruit on new spurs, while others can use the same spurs for several years. For example, figs, grapes, persimmon, and quince produce fruit on new shoots and one-year old wood. Pears, walnuts, and apples, on the other hand can produce fruit on the same spurs for several years. UC Davis offers a chart of fruiting wood characteristics that can help you decide what to remove and what to leave for another year. Did you know that large, unproductive branches are called bulls? I didn't either.
Renewal pruning of raspberries and blackberries
Some varieties of raspberry and blackberry produce fruit on primocanes. These are fall-bearing varieties that produce the best fruit on first-year canes. While leaving them in place will provide some fruit the following spring, the quality and quantity are usually poor. For these berries, it is better to cut the canes back to ground level in late autumn. This gives the plant time to pull carbohydrates from the leaves down into the crown and root system. These nutrients will be used to grow new canes in spring. Summer-bearing floricanes produce fruit on buds from second-year canes, so removing them at the end of year one would be problematic.
Some trees and shrubs can become so out of control that they risk falling over, severe disease infestation, or they simply look awful. In some (but not all) of these cases, rejuvenation pruning can be used to give them a new start on life. These plants are cut to ground level and allowed to start over from an established root system. Before you try this method, be sure to research the plant to make sure this is an appropriate choice. Cutting back some plants in this way will kill them.
Whole tree pruning
Traditionally, trees that produce fruit in new growth, such as cherries, are pruned by removing selective branches. Another method being studied is whole tree pruning, in which all the major limbs are removed each winter, leaving only 12 to 18 inch nubs. This method is not for the faint of heart, but it is gaining popularity among commercial growers.
Don’t be afraid to prune your trees and shrubs. It is an excellent way to help your plants to stay healthy and productive. As you move around under the canopy or peaking into the center of your shrub, you may even discover a new pest or disease before it gets out of hand!
Nitrogen is the single most limiting factor in plant growth.
There is far more to tell about nitrogen than we have time or space for here, but I hope that this summary will give you a better understanding of what makes nitrogen so important in the garden, and encourage you to learn more.
What is nitrogen?
Nitrogen is an element, like hydrogen or oxygen. The Earth’s atmosphere is 78% nitrogen, but it is in a form that plants cannot use. Nitrogen is the first number you see on a bag of fertilizer. It is the “N” of NPK. Since pure nitrogen boils away at -320 degrees Fahrenheit, you won’t be buying a bag of pure nitrogen at your local garden center. [If you’ve ever had a dermatologist “freeze” off a wart or precancerous area, they are often using nitrogen.]
How plants use nitrogen
Nitrogen is a fundamental building block for chlorophyll and plant enzymes and proteins, including a plant’s DNA. Without nitrogen, photosynthesis cannot occur. Some crops use more nitrogen than others. Cucurbits, such as melons and squash, are relatively light feeders. Heavy feeders include sage, artichoke, potatoes, onions, lemongrass, and corn. If you are growing plants in containers or straw bales, plants should be monitored closely for signs of insufficient nitrogen.
Not enough nitrogen
Stunting and chlorosis are the two most common signs of insufficient nitrogen. Nitrogen is highly mobile within the soil and in plants. Nitrogen deficiencies are frequently seen as a pale area down the middle of each leaf, with older leaves affected first. This happens because the plant pulls nitrogen from older leaves to feed newer leaves. Nitrogen deficiencies in peach and nectarine tend to show as red areas on leaves (where photosynthesis is no longer occurring properly). Nitrogen deficiency and sodium toxicity are common in San Jose, California. Our heavy clay also reduces nitrogen levels in the soil.
Too much nitrogen
Too much nitrogen can be just as bad as not enough. Excessive nitrogen is seen as darker than normal leaves and more vegetative growth than fruit or flowers. Too much nitrogen can burn plants, and it can cause erratic or reduced budbreak. Too much nitrogen can also stimulate new growth that may be vulnerable to cold weather, thrips, leaf spot, Verticillium wilt, aphids, and scale. This is why the timing the use of fertilizer is so important.
Types of nitrogen
The Nitrogen Cycle refers to the conversion of atmospheric nitrogen into chemically reactive forms that attach themselves to other elements, creating ammonia or nitrate based fertilizers. Crops that prefer more acidic soil, such as blueberries and potatoes, seem to prefer ammoniacal nitrogen based fertilizers over nitrate based fertilizers. As plants absorb nitrates, they increase the soil pH, making it more alkaline. California soils are already more alkaline than many plants prefer. When plants take up ammonium, the soil becomes more acidic.
Nitrogen - a fleeting plant nutrient
Nitrogen is quickly used up by nearby plants. It also deteriorates rapidly and is leached out of soil by rain. This deterioration is largely a function of moisture and temperature. As temperatures rise, there tends to be less organic matter in soil. As moisture increases, so does organic matter. This is why it is so important in our hot, dry California weather to regularly add compost to our gardens and landscapes.
Native Americans used the Three Sisters Method of growing corn, beans, and squash together. Beans, being a legume, are host to bacteria that convert atmospheric nitrogen into forms usable by plants. Planting them all together provided the corn and squash with extra nitrogen early in their growing season. Some tribes added dead fish or eels when planting, which provided even more nitrogen. Fish emulsion is a mild source of nitrogen. According to study by the Washington State University Extension Office, coffee grounds contain 10% nitrogen after brewing. Blood meal, cottonseed meal, alfalfa meal, and feather meal are all good sources for nitrogen. Urea and urine both provide high levels of nitrogen.
Finally, if you are like many gardeners who plant marigolds to deter pests, you may want to plant them away from any legume crops. It is rumored that the same chemicals that make marigolds beneficial can also interrupt the nitrogen-fixing capabilities of legumes, such as peas and beans, though I have not yet found any scientific proof.
Spinosad is an organic insecticide originally made out of fermented bacteria found in soil where sugarcane was grown. Actually, it was first found in a rum still. Bootleg bacteria, anyone?
Let me start by saying that anything called insecticide, organic or otherwise, is deadly to something. That’s the point, right? Since not all insects are our enemies, that can be a problem. Before we explore the benefits of spinosad, let’s keep in mind that spinosad can be highly toxic to honey bees and other pollinators, under certain conditions. Now let’s find out how it works and how we can use it safely.
How spinosad works
Spinosad works by messing with an insect’s neurological system, creating hyperactivity, tremors, and muscle contractions. Ultimately, the insects go into seizures and then become paralyzed, out of pure exhaustion, and then they die. Insects can be affected by eating or touching this insecticide. Chemically, there are over 20 different natural forms of spinosads and 200 different synthetic forms. These synthetic forms are called spinosyns. The spinosad formulas that you can buy are made from two of the synthetic types, spinosyn A and spinosyn D.
Uses of spinosad
Spinosad is used on a large number of crops, against many types of insects, including:
Safe use of spinosad
According to the University of California Dept. of Agriculture & Natural Resources (UCANR), spinosad has a residual toxicity that can last anywhere between 3 hours to more than 24 hours, depending on application rates and formulation. UCANR recommends using 1.25 to 3 ounces per acre. That sure doesn’t work out to be very much for my little 1/5 acre property! As with any other insecticide, it is probably a good idea to stay out of the area yourself for the same time frame. You know, just in case. Spinosad should not be used within 24 hours of harvesting.
Protecting pollinators from spinosad
Spinosad is sold under several different brand names, including Bull’s Eye, Entrust, Natular, Protector Pro, and Success. To reduce the risk to honey bees and other pollinators:
If you really must use an insecticide, spinosad is probably a better choice than non-organic products that build up in the soil and encourage the evolution of resistant species. Personally, I prefer tolerating a little bit of damage, monitoring regularly, and handpicking the pests I see. It’s not as effective as, say DDT, in the short run, but it serves me best in the long haul.
Hardening off is a process that acclimates new plants and seedlings to your microclimate.
When a plant finds itself in a new environment, it must make several adjustments to all the changes. This is called ecesis. Sudden changes in temperature, sun exposure, and wind can be fatal to plants raised in a greenhouse. Most plants sold commercially are raised in greenhouses. Greenhouses are generally warm, moist, protected areas that allow plants to get a good start. It does not, however, prepare them for the outside world. Many nurseries use equipment that bends the plants over, back and forth, a few times each day, in an effort to mimic the effects of wind. This strengthens the plants through a process called thigmomorphogenesis. It helps, but you can significantly help new plants become acclimated through hardening off.
When to harden off plants
Since all newly acquired plants have the possibility of carrying pests or disease, it is always a good idea to start them off in a protected quarantine area for 40 days. This gives you time to watch the plant for signs of infection or infestation. It also provides an opportunity to see what conditions best help the plant thrive, and it gives you time to carefully decide where in the garden this new plant will go. Depending upon the climate tolerance of the plant species, you may have to wait until it is a couple of weeks before your last frost date before you begin hardening off.
How to harden off plants
Plants should be brought outside for a few hours each day, at first. They should be in a location protected from wind, with filtered or morning sunlight. Increase the amount of time and sunlight by an hour or two each day until they are outside all day. If temperatures allow, plants can now be left outside overnight. If you are growing plants in a cold frame, you can harden them off by opening the frame a little more each day until the lid is no longer needed. Hardened off plants can now be installed in the landscape or garden, with a significantly higher chance of success.
Which plants need hardening off?
Generally speaking, bare root stock does not need hardening off. There are no leaves to dry out or get sunburned. Young blueberry plants, garden sale seedlings, and seeds you have started yourself indoors will all benefit from hardening off.
By gradually getting plants used to your microclimate, they are more likely to thrive.
Don’t let the name scare you off. Bacillus thuringiensis (called “Bt” to make things easier) is a naturally occurring, rod-shaped, pest-killing collection of bacteria found in soil.
In addition to occurring naturally in soil, Bt can be found on leaves, in animal feces, and in flour mills. It is even found living in the gut of the caterpillar stage of some moths and butterflies.
Being a living thing, Bt doesn’t handle extreme heat very well. Because of this, you will only want to buy as much as you will use in a single growing season, and store it in a cool, shady location. One advantage to being easily killed is that it reduces the likelihood of pests developing a resistance, the way they do for many chemical treatments.
Bt is used against a wide variety of garden pests, including whiteflies, budworms, moths, flies and mosquitoes, aphids, beetles, blackflies, leafhoppers, wasps, and sawflies. Unfortunately, Bt can also negatively impact important beneficial insects, such as honey bees and parasitic wasps. (There are no easy solutions…)
Bt reproduces using spores. Now, there are spores that generate plants such as mushrooms, moss, and other eukaryotes. This is a different kind of spore, called an endospore. Endospores are not seeds or embryonic offspring. Inside the endospore, a dormant, bare-bones, reduced version of the original bacteria divides within its cell wall. Then one of these divisions swallows the other one! This behavior allows endospores to remain dormant for hundreds (some say millions) of years without food. Endospores can resist ultraviolet radiation, extreme temperatures (even boiling water), and chemical disinfectants.
Death by bacteria
Bt are 1 µm (micron) wide and 5 µm long. That works out to over 25,000 Bts standing next to each other to cover one inch. If they had feet, that is… Regardless of their diminutive size, MicroWiki describes the [brutal] process of Bt pathology this way:
There are hundreds of strains of Bt, and each one attacks a different type of plant (or animal). Bt is related to the same bacteria that cause anthrax (Bacillus anthracis) and food poisoning (Bacillus cereus), but Bt is believed to be harmless to humans and animals. The European Food Safety Authority approved the use of Bt, but pointed out that many safety claims lack adequate scientific proof. The Organic Materials Review Institute (OMRI) has approved Bacillus thuringiensis for use in organic farming with certain restrictions, including the use of crop rotation, proper sanitation, creating habitat for beneficial insects, and minimal use of Bt treatment. There are 5 subspecies of Bt available in the U.S.:
There are other Bacillus thuringiensis that claim to attack nematodes, flatworms, and mites. These forms are given mind-numbing names like Cry5B, Cry6A, Cry14A, Cry1A, Cry3A, and Cry4A. Unfortunately, research hasn’t shown them to be nearly as effective as advertisements claim, though they do provide some aid. These bacteria are also being used to genetically modify several food crops, including corn.
Bt is used on a wide variety of crops. The short list includes stone fruits, citrus, cruciferous vegetables, apples, artichokes, melons, berries, tomatoes, lettuce, and grapes, just to name a few. But Bt only works on insects when it is ingested. This normally occurs in the larval stage. Eggs and adult insects are generally not affected, so timing is important. Also, Bt degrades quickly in sunlight, so early morning or evening applications are best. These steps can help you get the most out of Bacillus thuringiensis:
You can find Bt at most garden centers. It comes in concentrated form or in a ready-to-spray bottle.
IMPORTANT NOTE: NOT ALL Bt PRODUCTS SOLD AS EFFECTIVE INSECTICIDES CAN ACTUALLY DO THE JOB. BE SURE TO LOOK FOR THE SUBSPECIES LISTED ABOVE.
What kind of plant is that?
Has that ever happen to you?
It happens to me a lot. I will plant seeds in what appears to be the ‘perfect spot’, confident that the location will trigger a memory of what I planted there, except that sometimes it doesn’t. Sometimes, I have no idea what it coming up. In those cases, I have to wait until the plant reaches a recognizable size. That’s fine when it turns out to be what I planted, but it’s a waste of soil, sun, and space when it turns out to be a pesky weed that has choked out the intended resident.
Using plant markers is a handy way to remind yourself of what is planted and where. This can help you take better care of your plants, especially when it comes time for feeding, propagating, or transplanting. Plant markers can also be used as lovely yard art. Here are several ideas for free (or nearly free) plant markers for your garden.
If your family eats popsicles, have them save the sticks. This works best if you create a place for them to collect: a cup, box, planter pot - something convenient. These wooden sticks will not last forever, usually no more than a single growing season, but they are fabricated with the intention of touching food, so I assume they are relatively safe. Popsicle stick plant markers absorb gel pen and marker colors nicely, so you can make them look colorful and easy to read. These plant markers are an excellent choice for seed starting. When the begin to wear out, you can simply toss them into the compost pile.
I used to own a private school, called Children’s Academy, in Virginia. We were on three acres and had a vegetable garden, a butterfly garden, and a wide variety of trees, shrubs, and other plants. I encouraged my students to go out and select a plant, conduct research, and identify it. Whoever identified it first was given the opportunity to select a large rock, paint the common and scientific names of the plant on the rock, and then place it near the plant. The kids seemed to enjoy it (they became a bit competitive about it, at times) and the rocks made beautiful reminders of what was growing around our school. You can do the same thing in your yard, especially for the perennials.
If you have a log or decent sized branch laying around, and a saw, you can cut disks of wood that make lovely plant markers. This requires some effort if you do not have a power saw, but it is certainly do-able. The wood grain looks really nice, without standing out too much, and the edge can be sunk into the soil enough to make it stand up or you can lay them flat.
Yard sales & garden markets
Yard sales and Master Gardener events are excellent sources for low-cost garden tools, and plant markers are no exception. Flatware, old mugs, saucers, and many other durable materials can be had for practically nothing and then painted with plant names.
Give yourself permission to be creative. Heck, go for flamboyant! You can add a touch of your personal creativity to the garden or landscape while making it easier to recall where all of your plants are!
Imagine a world without cabbageworms, leafminers, or whiteflies… Or one without Sudden Oak Death, bacterial spot, or tomato yellow leaf curl…
Such would be our gardens, had quarantines been in place and enforced sufficiently. Alas, it is not to be.
Imported plants that are not adequately inspected, nursery stock that is sold in spite of being infected or infested, and the use of grocery store produce to start a garden are responsible for a profound amount of damage to the environment. According to The Nature Conservancy, invasive species cost the U.S. economy $120 billion each year. The U.S. Forest Service echoes those figures, adding that 81 million acres of American soil are at risk due to these pests and diseases, and that 42% of threatened or endangered species are being pushed out by these invasives. Scale those figures down to the size of your garden and decide for yourself if it is worth the risk.
What is a quarantine?
To quarantine something means to keep it away from everything else, for a period of time, to avoid the spread of disease. In the world of plants, quarantines are used to halt the spread of diseases, pests, and other plants (weeds). In Italian, quarantina means 40 days and that’s where we get the idea behind quarantine. By isolating plants for 40 days, you are more likely to see signs of pests, diseases, or weeds, before exposing all of your other plants.
When to quarantine a plant?
Plants that are new, infected, or infested should be quarantined whenever possible. The easiest case, and the most useful, is when you bring a new plant home. As much as you want to add it to the landscape, 40 days in quarantine can prevent a whole lot of work later on. Plants new to your property can never be guaranteed disease-, pest-, or weed-free. Blithely adding it to your landscape may work out fine, or it may introduce a devastating disease that can stay in the soil for decades, introduce pests that you will have to battle every year forever after, or add even more weeds to your To Pull list. To avoid these risks, you can place new plants in quarantine until they have shown themselves to be safe for your garden or landscape. Containerized plants that develop problems are pretty easy to quarantine. Established plants are a bit more difficult.
How to quarantine
Ideally, new plants should be kept separate from all others for 40 days. This is especially true for houseplants, because there aren’t very many natural predators in your livingroom. This can be done by placing the latest addition in a different room, across the room, or in a clear plastic bag. The bag method is the most effective because it creates a barrier that you can see through. Established plants, such as fruit trees, are difficult, if not impossible to quarantine. In cases such as Citrus Greening, trees must be destroyed. If you suspect an invasive pest or disease in one of your established plants, contact your local County Extension Office for help.
Alternatives to quarantine
Some of us can’t (or won’t) invest 40 days of waiting before adding a new plant to the garden. When this is the case, use these tips to reduce the likelihood of problems:
Government mandated quarantines
In 1912, the Plant Quarantine Act was enacted, giving the U.S. government the right and responsibility of preventing the spread of pests and diseases through nursery stock and other plants. This act evolved into the Plant Protection Act of 2000. If you’ve ever driven across the California state line, you have seen the inspection stations and you may have been required to hand over an apple, a bag of green beans, or a butternut squash before being allowed in. From a visitor’s point of view, this Orwellian treatment may feel extreme, but it’s not. In fact, too many invasive pests and diseases are making their way around the globe because of too few precautions.
Grocery store produce
As tempting as it may be (I know, I’ve done it), do not use grocery store produce to seed your garden. Garlic, onions, and leeks look easy to start from your discards (and they are), but they can also carry fungal diseases that will never go away. Take a look at the current list of current quarantines in California to see some of the other vulnerable crops.
To quarantine or not to quarantine? That is the question. The answer is up to you. As you think it over, consider the fact that many pests can generate a surprising number of offspring pretty quickly. For example, a single aphid can turn into 600 billion descendants in a single season, according to entomologist Stephen A. Marshall.
Forty days of caution, or a lifetime of reactionary treatment.
Ecesis (eh-SEE-sus) is the establishment of a plant in a new habitat.
According to some, ecesis refers to plants becoming newly established in areas that were barren or previously devastated. However you define it, a better understanding of ecesis you to help your plants thrive.
Note: In the past, I have lived in duplexes whose tiny patch of soil was nothing more than a moonscape. Apparently barren, it didn’t take long to create a lush, edible landscape. Before you start, however, you need to know that each time you plant a seed, install a seedling, or transplant an established plant into a different container or location, ecesis is a factor.
Once a plant is established, there is a whole lot more going on than meets the eye:
Moving this plant to a new location, or into a bigger container, is a shock that can slow or halt growth, temporarily or permanently. Soil microorganism must repopulate the area. Roots that are damaged or overly stressed during transplanting mean less water and minerals available to the aboveground portion of the plant. (Ever have a plant wilt on you after transplanting?) Below, you can read about the many factors of ecesis that may impact plants being added to your garden or landscape.
Light and temperature
Significant changes in light and temperature can be devastating, or they can be necessary to a plant’s development. Some plants won’t put out fruit without enough chilling hours. Some seeds won’t germinate without being exposed to fire or ice or other damage to the seed hull. Most plants need a period of acclimation, called hardening off, when moved from one environment to another. Too much sun all at once and tender seedlings can be scorched. For your plants to be the most successful, choose varieties suited to your microclimate, be it a balcony, a farm, or a suburban yard.
Wind and other airs
Plants added to an environment with more wind than they are used to are going to need more water. Wind dries plants out. Wind can also blow containers and tall plants over, risking breakage. Placing containers against walls or tying plants to stakes can help prevent these problems. Insufficient air flow, whether through plant structure and improper pruning, geography, other plants, or fencing can increase the chance of fungal diseases occurring.
Problems with pavement
Plants installed near sidewalks, driveways, and buildings face a unique set of potential problems. The pavement and concrete create a heat sink, exposing plants to much more heat than is good for them. Also, these structures are usually designed to move water away, which means plants may need extra irrigation. And even easier solution is to select plants that can handle a lot of heat and very little water. Container plants grown in dark colored pots face similar problems. The dark color absorbs heat and the limited amount of soil can mean frequent drying out.
From whence they came
Where a plant came from should always be taken into account when installing it someplace new:
Containers If a container plant is being moved into a larger pot, it is a good idea to keep it in the exact same environment, or a slightly more protective version of the same place, until the roots have a chance to recover.
Nurseries Plants grown in nurseries are accustomed to climate-controlled warmth and moisture; they are often infested with aphids and other pests; they may have been sprayed with pesticides, fungicides, or herbicides; they may be carrying diseases or weed seeds. It is a good idea to have a quarantine area for all new plants that reduces stress to them and the chance of infection to established plants.
Soil Seeds started in potting mix and container plants that are used to loose soil will need some help when being transplanted into the ground. This is especially true in the Bay Area, where we mostly have heavy clay soil. If you dig a hole in the ground, be sure to rough up the sides of the hole. Smooth clay is almost as impenetrable as a ceramic pot.
Just as we need a period of time to get used to a new home or job, plants need a little TLC when they are moved into a new environment. Providing this care ensures that the move will be a successful one!
Have you ever seen trees with knobby limbs, bare of all leaves and twigs? It’s called pollarding.
Pollarding is a pruning method that limits the size of trees and shrubs. Unlike shearing, which trims everything past a certain point, pollarding cuts back all new growth. This stimulates regrowth that will bring it back to full size.
Pollarding was first done by the Romans and we still use it today. The word pollarding comes from ‘poll’ which refers to the top of the head (as any horse enthusiast knows). To ‘poll’ someone was to cut their hair. [I wonder if polling at the voting booth came from the same root - asking what is inside someone’s head. It makes sense, but I digress.]
Originally, trees were pollarded to provide food for livestock and fuel for winter fires. [Peasants were allotted a ration of firewood and other materials from the king’s trees in something called an ‘estover’. Pollarding stimulates vigorous upright growth, which turns into straight boards for boats and fence material. Thinner upright stems were also used to make baskets and garden bowers. Pretty smart for 2,000 years ago, eh?
Which trees are pollarded?
Pollarding is not recommended for all types of trees. Many conifers do not handle pruning very well. Their twigs tend to die back to the branch they grew out of, providing entry points for pests and disease. Yew are one exception. Trees that respond well to pollarding are those that tend to send out shoots quickly, a characteristic called ‘epicormic’, including:
When & how to pollard trees & shrubs
Pollarding is normally done annually in late winter. Maple trees are pollarded in summer to avoid bleeding sap. In most cases, each year’s pollard cuts should be just above the previous year’s cuts. Because pollarding large trees involves chainsaws and ladders, this is best left to the professionals. Small trees and shrubs can be pollarded with hand pruners and a tree saw. When evaluating a shrub for pollarding (or other pruning) keep in mind the future desired shape and size as you cut. Where each cut occurs, a mass of new stems will appear.
Advantages of pollarding
In addition to size maintenance, pollarding provides other benefits:
Disadvantages of pollarding
Pollarding is stressful to trees and shrubs and it must be done every year or two, to avoid limb breakage. The sprouts that appear after pollarding are attached weakly to the ‘knob’ and may break off. Mature trees that have not previously been pollarded can be killed by the process if it is done incorrectly. Even healthy trees and shrubs are exposed to pests and diseases after pollarding is done.
Whether you use pollarding or not, now you know what all those knobby looking trees are about!
You can grow a surprising amount of food in your own yard. Ask me how!
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