Bacterial wilt is a disease that causes members of the gourd family to wilt.
Bacterial wilt is caused by a bacterium called Erwinia tracheiphila. It mostly affects cucumbers and muskmelons, but it can also infect pumpkins and squash.
Symptoms of bacterial wilt
Damage caused by bacterial wilt looks a lot like feeding damage caused by squash bugs. As the bacterium begin to multiply within vascular tissue (veins), they clog the xylem, which makes the plant wilt. The sap of an infected plant will be milky colored and able to create a viscous string. (Ew!)
Striped and spotted cucumber beetles carry this disease. The Erwinia bacteria that cause this disease can live in the gut of their carriers for quite a long time. The bacteria can be transmitted as these pests feed and through contact with frass.
Bacterial wilt treatment
Unfortunately, there is no effective treatment. Once a plant is infected, it is too late. Since the infected plant poses a health risk to its neighbors, it should be removed and thrown in the trash. Any tools that came into contact with the plant should be sanitized in a solution of one part bleach and nine parts water. Bathroom disinfectant can also be used. To reduce the chance of infection, controlling beetle populations and maintaining healthy plants are your best bet.
Bright yellow pests on milkweed? It’s oleander aphids!
Many of us have planted region-specific milkweed plants to support Monarch butterfly populations. What we didn’t know, was that we would also be inviting a new pest into our gardens: oleander aphids. These pests can suck the life out your milkweed plants before the Monarchs ever have a chance.
Oleander aphid description
Like other aphids, this species is small (1.5 to 2.6 mm), pear-shaped and soft-bodied. Oleander aphids, in particular, are bright yellow, with black legs, wings, and cornicles. Cornicles are tiny spikes on an aphid’s back that can excrete defensive fluid. [My dog did that once, after he got into some old pork bones. It wasn’t pretty.] Actually, these defensive fluids are cardiac glycosides that the aphids take from their host plants! Cardiac glycosides are known heart poisons. Luckily, these pests cluster on new stems and are easy to spot. And those defensive fluids won’t hurt you.
As much as I dislike aphids for their plant-damaging and disease-carrying capabilities, I have to give credit where it is due. These soft-bodied bugs really are amazing. Female aphids (and almost all of them are female) are viviparous and parthenogenetic. Wait! Come back! Let me explain. Viviparous means that offspring develop within the mother, the way we do. Parthenogenetic means fertilization by a male is not needed to produce offspring. Not like us. Most aphids do not have wings. But, when they become too crowded, or when a plant starts senescing (dying), some adult aphids emerge with wings. That would be something like all human beings being born 40% smaller, simply because we start running out of room and resources. Hmmm… But I digress. Let’s get back to aphids.]
Oleander aphid damage
Like other sap-sucking insects, oleander aphids pierce plant parts to tap into the phloem of the host plant. Think of it as diabetic mainlining. This nutrient rich food source blows through an aphid’s body, creating a sticky sweet residue called honeydew. Honeydew is a petri dish for bacterial and fungal growths, such as sooty mold. Also, the aphid tendency to feed in clusters stunts growth and deforms flowers and leaves, crippling milkweed and oleander plants. Vinca, periwinkle, and frangipani are also affected.
Oleander aphid management
If you’re not squeamish, you can squish the aphids between your fingers. Or, if you see a stray lady beetle wandering around elsewhere in the garden, gently scoop them up and show them where the feast can be found. If those are not options, you can use a strong spray of water from the hose to dislodge the interlopers, or make your own insecticidal soap. Do this by combining one gallon of water and one teaspoon of liquid dish soap. Do not shake. It will take too long for the bubbles to subside. It is much better to stir or gently roll the solution around in a clean, repurposed plastic jug. Then, put the solution in a spray bottle and let ‘em have it! On plants with heavy stalks, you can interrupt support for aphids from ants by painting the stalk with a sticky barrier. This won’t get rid of the aphids, but ti will make them more vulnerable to their natural enemies.
Unfortunately for the Monarchs, nearly all of these methods will harm their offspring along with the aphids. Lady beetles will eat Monarch eggs and larva, the soap will kill them, as well. There is a parasitic wasp, Lysiphlebus testaceipes, that feeds on oleander aphids, as do syrphid flies, so avoid those broad spectrum pesticides. If you see dried up, brown husks of aphids, you will know that you have these helpers in your garden.
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.
Katydids are cousins to crickets, grasshoppers, and mole crickets, and you do not want them in your garden or landscape.
There are over 250 different species of katydid in North America (over 2,000 species worldwide). The name ‘katydid’ refers to the sound made by males when they are trying to attract receptive females.
Katydids can be difficult to see. It’s not that they are small, because they aren’t. Mature katydids can range from 1/2” to nearly 5” in length! The difficulty lies in their resemblance to leaves and the fact that they are mostly nocturnal. During the day, they hide out in trees and shrubs, blending with the foliage. They tend to have a bright green, blade-like body, with large hind legs. They look a lot like flattened grasshoppers, but with extra long antennae (or ‘horns’). Very often, the only notice you will get that katydids are present is the damage they cause and a male’s strident chirp.
Katydids (Tettigoniidae) start out as oval-shaped eggs that are laid in rows, at the end of summer, in the soil and in host plant stem holes. These eggs often hatch out looking like tiny adult katydids with big heads and small wings. Nymphs of some species of katydid mimic spiders or leaf-footed bugs in their early stages of development to avoid being eaten. As they feed and grow, they shed their outer exoskeleton and go through several instars before reaching adult size. As summer nears its end, males start singing to attract females. Females use the volume and fluency of a male’s chirp to judge his fitness level. In order to ensure a healthy pregnancy for the female, male katydids provide their (temporary) mates with a ‘nuptial gift’ of sperm and highly nutritious food.
Katydids bite and chew many different plant parts, including leaves, stems, seeds, bark, buds, flowers, roots… okay, pretty much every part of a plant is vulnerable to katydid feeding. The damage often looks like it was caused by caterpillars or grubs. Citrus, peaches, pears, blueberries, apricots, plums, and pomegranates are just a few of a katydids menu items.
These pests are super fast, and difficult to catch. I use a butterfly net to catch them, and then I feed them to my chickens, who are very happy to help reduce my garden’s pest populations. Commercial growers often use spinosad to control katydids. I have read that katydids can inflict a painful bite or pinch, but I never give them the opportunity. Apparently, in Uganda, people eat katydids.
Katydids as thermometers
If you hear a katydid, you can estimate the ambient temperature using Dolbear’s law. According to Amos Dolbear’s 1897 calculations, you can count the number of cricket chirps that occur over a 15 second period and then add 40 to that number for a reasonable estimate of temperature. If you are using katydids for this experiment, it is suggested that you add 37, instead of 40.
If you hear katydids in the garden, go get your butterfly net and start hunting! These suckers can reproduce exponentially!
Heat islands: tropical paradise or slow death for trees?
We’ve all seen it, but most of us don’t understand what it means. Naked upper branches of trees, singed leaves, neighborhood shrubs struggling to survive, our own garden and landscape plants growing less well than expected are all signs of heat island effect.
What are heat islands?
The term ‘heat islands’ refers to land that used to be soil, bushes, and trees, and is now concrete, asphalt, and buildings. Before all that development, natural cycles and the permeability of the soil kept things cooler and healthier for plants. All the impervious, manmade materials that now cover up 3% of the earth’s landmass absorb heat, creating a zone of higher temperatures called heat islands.
Do I have heat islands?
Unless you live in a tent in the wilderness, yes, you have heat islands. Driveways, patios, extended foundations, concrete paths and walkways, roofs, sidewalks, and the street in front of your home can all create their own heat islands.
How do heat islands impact landscape plants?
Plants installed in or near heat islands must contend with soil temperatures that can be 50 to 90° hotter than the air. This means, on a scorching California summer day, when the air is 95°F, your plants’ roots may be struggling to survive temperatures as high as 185°F! All this strain takes its toll. Most trees reach what is called a ’thermal death threshold’ at 115°F. Held too long at temperatures above this point and even the healthiest tree can die. Even if they survive, plants growing in heat islands have significantly shorter lifespans and are more susceptible to pests and disease. Also, things don’t cool down for these plants as the sun sets. While we may enjoy the lower temperatures of evening, concrete and asphalt hang on to all that absorbed heat, slowly releasing it into the immediate area, making evenings the hottest part of your plants’ day.
Impact of heat islands on water use
Plants growing in heat islands need as much as 50% more water than the same plants grown elsewhere. Since a mature tree can use up to 250 gallons of water a day during the peak of summer, that percentage can translate into a lot of water! Also, if you re growing edibles, such as cucumbers, peppers, lettuce, broccoli, or cauliflower, in a heat island, the stress can cause these foods to turn bitter, or bolt.
How can you help plants in heat islands?
City managers are working toward reducing the heat island effect and you can. too! Use these tips to help your plants survive the heat island effect:
Since plants that are growing in heat islands are already under a lot of stress, be sure to monitor for pests and diseases regularly, so that you can apply treatments right away, before things get out of hand.
Reducing heat islands on your property
There are many steps you can take to reduce the number of heat islands on your property. Not only will this help your plants to be healthier, it also reduces energy bills (if you use A/C), water consumption, and emissions from energy production. Here are just a few of the ways you can reduce the number of heat islands on your property:
Help your plants and the environment by eliminating heat islands around your home.
Brussels sprouts: prehistoric weapons, baby cabbages, or healthy garden addition?
Many years ago, my mother showed up for a Thanksgiving dinner armed with what looked like a medieval weapon. Having never seen the unopened flower buds still attached to the stalk, it confused me, at first. If you have never seen Brussels sprouts growing on a stalk, you are in for a surprise!
A little history
Brussels sprouts (Brassica oleracea) were first grown as far back as the 5th century throughout the Mediterranean. The Romans liked them, so they moved around quite a bit. They were widely grown in Belgium, back in the 16th century, hence the name Brussels. These plants prefer cooler, coastal weather, to they are a winter crop in California. Lucky for us, a touch of frost actually makes Brussels sprouts sweeter! In fact, California grows Brussels sprouts on several thousand acres each year.
How to grow Brussels sprouts
Brussels sprouts seeds can be planted in the Bay Area in July and August, and transplants can be put in place as late as September. Brussels sprouts and other cole crops love growing in raised beds, with their nice loose soil with plenty of nutrients. (It makes weeding a lot easier, too!) These plants do not perform well in poor soil. Each plant will need an area 2 to 3 feet square, so thin accordingly. Seeds should be planted 1/2 an inch deep and watered well. Keep the soil moist until germination occurs. A nice light mulch can help keep that moisture in place. If you are placing transplants, be sure to dig the planting hole large enough to accommodate the root ball plus the stem, up to the first set of true leaves. Water thoroughly, to eliminate any air pockets, and water every day for the first week. After that, allow the soil to dry out between waterings to prevent fungal diseases.
Pests and diseases of Brussels sprouts
Like other members of the cabbage family, Brussels sprouts are host to many different pests: earwigs, cutworms, flea beetles, beet armyworms, crickets, cabbage aphids and cabbage maggots, whiteflies, loopers, imported cabbageworm, harlequin bugs, nematodes, slugs and snails, thrips, wireworms, and diamondback moths are the more common pests here in California. Brussels sprouts diseases include downy mildews, powdery mildew, bacterial leafspot, bacterial soft rot, while mold, verticillium wilt, phytophthora root rot, clubroot, and ring spot (black blight). Clearly, with so many fungal diseases threatening our Brussels sprouts, moisture is a factor. Brussels sprouts should be on a 2 to 4 year crop rotation to break these disease triangles.
Caring for Brussels sprouts
As your plants grow and start to produce buds, break the lower leaves off, over a period of a few weeks, starting from the bottom of the plant. Brussels sprouts are susceptible to sunburn damage and will bolt if temperatures get too high. You can help prevent these problems by covering them with a 50% shade cloth or a double layer of row covers. You can also plant them in a location that is protected from direct sun in the hottest part of the afternoon. This isn’t much of a problem as we get into winter.
Try adding just one Brussels sprout plant to your garden this fall and share the rest of your seeds with family and friends!
Biochar is being touted as an environmentally friendly way to remove carbon dioxide from the environment, while amending your soil, but is it as friendly as proponents claim?
What is biochar?
Biochar is charcoal made from plant matter burned in a low oxygen environment. You know those big chunks left over in your fire pit? That’s pretty much biochar.
How does biochar act as a soil amendment?
Biochar is said to increase the fertility of acid soils (low pH). Here, in the Bay Area, our soil is more alkaline (high pH), so biochar wouldn’t be a good idea whether it works or not. It is also claimed to act as habitat for many beneficial soil microorganisms. This may or may not be true. How many living things do you find in your fireplace?
How is biochar supposed to help the environment?
Enthusiasts claim that burning vegetation and burying the resulting biochar will sequester tons of carbon in the soil. Of, course, it’s not that simple. The initial burning, alone, releases carbon into the atmosphere.
Bottom line: not enough research has been conducted to prove the claims being made about biochar.
My suggestion: stick with mulch and compost, and drive less.
Echeveria are succulents native to Texas, Mexico, and Central America.
While most stonecrops are not edible (my plants of choice), these plants serve well in gardens and landscapes, protecting areas that would otherwise go unplanted. They require very little care, are drought tolerant, and easy to propagate.
It can be difficult to distinguish between different types of succulent plants. They nearly all grow in a rosette shape, have thick, rubbery or waxy leaves, and tend to have hairs or spines. They also tend to spread, self-propagating wherever conditions are favorable. Echeveria, in particular, tend to reproduce by generating stalked offspring, called ‘offsets’, that appear from underneath in a behavior frequently called ‘hen and chicks’. Echeveria are polycarpic, which means they can produce flowers multiple times. In winter, many echeveria plants lose their leaves, though not all.
Echeveria pests and disease
Rot and frost are problems for echeveria. Frost, particularly after a rain, can kill most succulents. Leaves that have begun dying off should be removed to avoid spreading fungal disease throughout the plant. Mealybugs and aphids can be troublesome.
Nearly all succulents, or stonecrops, can be propagated from a single, healthy leaf. Simply break it off and lay it on loose soil and water regularly. Once roots develop, you can plant it wherever it will receive plenty of sun. You can also break off an offset and transplant it where you want it. Non-hybrids can also be started from seed.
Growing conditions can cause extreme variations in shape, size, and color. If you can’t grow food, grow plants that take as little care, food, and water as possible. Echeveria certainly fits the bill.
Aeoniums are a genus of plants that take little to no care and look better each year.
While I generally prefer edibles, sometimes you have a space in the landscape that you just can’t find the right plant for - aeoniums might be what you need. And while they may not be a familiar flavor, many aeoniums are edible. You have seen these plants many times before, but you may be surprised to see just how lovely they can become, given the chance.
Aeonium [ay-oh-nee-um] is a group of succulents known to the Greeks as aionos, which means ageless. They earn this name because they are monocarpic, meaning each rosette produces only one flower and then it dies. Originally from the Canary Islands, Morocco, and Ethiopia, these rugged succulents can thrive in the hottest weather. They perform well in containers and can be grown indoors if they receive enough light.
Most of the aeonium plants you see today are hybrids and they can look very similar to other stonecrops, such as sedum and echeveria. The biggest difference is that aeoniums often have fine hairs or spines on the edges (margins) of the leaves. Also, the leaves, which can be rounded or pointed, tend to be somewhat thinner than echeveria. When aeonium produce a flower, it is actually an inflorescence (a cluster of flowers) on a stalk that can reach 3 feet in height. These flowers can be very striking. The surface of aeonium leaves may be fuzzy, sticky, or smooth, and the stems can be scaly, smooth, hairy, or fissured. Plants stressed by drought or sunlight may exhibit red or purple highlights. This is not a concern. It is just what they do.
Types of aeonium
Most aeonium are classified as either low-growing or large. The large varieties include A. arboreum, A. holochrysum, and A. valvredense. Low-growing varieties are A. smithii and A. tabuliforme.
Caring for aeonium
Being tropical, these plants need strong light, good drainage, and watering only after long periods of dry soil. They do need protection from freezing temperatures so some sort of cover should be provided between the first and last frost dates. Too much rain can also cause rot.
Pests and diseases of aeonium
Aphid and mealybug infestations of the plant crown (where the stem meets the roots) can often be spotted by the presence of protective ants. Since many of these plants are edible and they contain a lot of water, many herbivores will feed on them, including squirrels, tortoises, and rabbits.
Being succulents, aeonium are easy to propagate from a leaf. This is best done in autumn, when plants are actively growing. Simply take a healthy leaf from the plant and place it in good soil, in bright shade, and water occasionally. Aeoniums readily self-seed, if they are in a good location.
The range of shapes, textures, and colors make these plants easy to play with when creating a rich visual tapestry in a landscape.
Pollinators are animals that carry pollen from flower to flower. This pollen then fertilizes female flowers, allowing plants to produce fruit and seeds.
Without pollinators, we would be in a bad way. The U.S. Dept. of Agriculture tells us, “Of the 100 crop species which provide 90 percent of the world’s food, over 70 crops are pollinated by bees.”
Fruit set failure often means there are not enough pollinators. Today, we will find out who the pollinators are and how to attract more of them to the garden.
How does pollination occur?
Some plants have the ability to self-pollinate. If pollen grains can be moved from the male (anther) to the female (stigma) within the same flower, it is called autogamy. If pollen grains are carried from the anther of one flower to the stigma of another flower, while still on the same plant, it is called geitonogamy. When the pollen must be taken to the stigma of a different plant it is called cross-pollination, xenogamy, or allogamy. In some cases, self-pollination occurs before the flower even opens! This is called cleistogamy, but it has nothing to do with pollinators, so we will leave those flowers to themselves - which is what they seem to prefer anyway.
How do pollinators move pollen?
Even in the case of self-pollinating flowers, something is needed to break the pollen loose from the anther so that it can stick to the stigma. Note for those with allergies: pollen is very sticky. Rubbing or rinsing with water will not remove pollen. Soapy water is needed. So, as pollinators land on a flower, pollen sticks to them. Walking around on a flower knocks pollen loose to fall on the stigma and to stick to the body of the visitor. Next, that visitor flies, walks, or crawls away, carrying that pollen with them. When they visit the next flower, pollen is knocked loose from the anther and the pollinator’s body and the chance of fertilization starts going up. Some pollinators end up looking like Charles Schultz’ Pig-Pen, a walking cluster of pollen grains. Others have evolved with pockets on their legs! Honey bees and other apid bees have a pollen basket, or corbicula, on their legs that hold pollen wetted down with nectar. Other bees have a pollen basket called a scopa, on their abdomen. Whether they carry it on purpose or not, pollinators are drawn to flowers for several reasons.
How flowers attract pollinators
Plants have evolved with specific characteristics that attract the best pollinators for their needs. In some cases, the relationship is very specific. Figs are only pollinated by a fig wasp. No fig wasp - no figs. In most cases, plants go for the hard sell to attract as many pollinators as possible, using several different characteristics:
Installing a wide variety of plants is one of the best ways to attract pollinators.
Who are the pollinators?
There is far more to pollination than just the 1,000 different species of native, mostly non-stinging bees in California (4,000 nationwide; 20,000 worldwide). Bats, flies, moths and butterflies, beetles, birds, wasps, even lizards and monkeys can be pollinators. For that matter, so are we! As we walk through the garden, pollen attaches to our skin and clothing, to be deposited on the next plant we approach. We have also been known to hand-pollinate plants on purpose. More often, pollinators co-evolve in mutually beneficial relationships with their nectar and pollen food sources.
How to attract pollinators
First and foremost, get rid of the toxins that kill these beneficials. Broad spectrum insecticides, herbicides, and pesticides, even when they claim to be safe, should be avoided. They cause too much of an interruption in the normal, natural cycle of things. Yes, it means a few more pests in the garden, but it also means less toxins and more pollinators.
Second, pollinators need fresh water. While you do not want to create mosquito breeding grounds, bird baths, fountains, and other water features make lovely additions to the garden while providing water for pollinators.
Third, you need to provide adequate food and shelter for pollinators. Now, before you go out and buy one of those new fangled bug hotels, know that research does not show they are effective. In fact, these artificial clusters end up being breeding grounds for pests and diseases of pollinators! Most native bees are ground-dwelling, so they wouldn’t use them anyway.
You can certainly install a bat house, but most of the shelter you provide will be the same plants you install to provide pollinators with food. Use these strategies to provide shelter:
Plants that attract pollinators
Plants can be divided according to the pollinators they attract:
Butterflies also benefit from access to your compost pile and a patch of mud. They use the mud as a source of both water and minerals, and they enjoy eating rotten fruit.
Going native through the seasons
Since evolution is a really slow process, one of the best ways to attract a wide variety of pollinators to your garden is to install native plants. Native plants already provide for these beneficial insects and birds. You will also want to ensure that there are flowering plants available throughout the year. Not only will this help the pollinators, it will make your garden and landscape look better! Perennial natives, such as manzanita, make the job of attracting pollinators far easier. Here is a list of some California native plants that attract and provide for pollinators:
Let it go to seed
All too often, we sabotage ourselves at the end of each growing season. Rather that pulling (never pull!) or cutting (better) spent plants, leave them in the ground (best) to go to seed. Not only will this provide for local pollinators, but it can also give you seeds for next year’s crops! I always let things go to seed. Now, as the seasons change, I find lettuce, escarole, cosmos, carrots, and more, growing where I never planted them, but where they can grow without any help from me.
Other causes of low pollination
Sometimes, pollinators are not the problem. Other causes of low pollination rates include:
For region specific planting advice, check out the Pollinator Partnership’s interactive tool. Simply type in your zip code and they provide valuable information about suitable plants that will attract pollinators.
As a child, I detested cauliflower above all vegetables.
It probably had a lot to do with the evening an encyclopedia salesman arrived just at dinner time. My single parent mother was bad at telling people to go away, so our already overcooked cauliflower sat on our plates, congealing, for nearly an hour. We didn’t have a microwave, so we had to eat it at room temperature. My mother’s rageful mood didn’t help our appetites.
Since those days, I have come a long way in my view of cauliflower. Apparently, so has the rest of the world. The peppery flavor of this cruciferous treat now grace menus in every meal. Grilled slabs of cauliflower are used as burgers, pureed cauliflower provides a low-starch replacement for mashed potatoes and potato pancakes, and the list of cauliflower recipes is getting longer every day. If that weren’t reason enough to add cauliflower to your foodscape, here’s another reason: you can start a cauliflower crop in the Bay Area twice a year!
When we eat cauliflower, we normally assume we are eating a flower, but we’re not. That is only true if you are eating broccoli. The part of a cauliflower that we normally eat is botanically known as ‘inflorescence meristem’. This plant tissue is a cluster of undifferentiated plant cells that form a ‘curd’. You know, the stuff Little Miss Muffet ate, sitting on her tuffet. Okay, she was eating a dairy product, but the appearance is similar.
How to grow cauliflower
Due to our local climate, cauliflower seeds can be started in January, February, and March, for an early summer crop, and again, in September, for a winter crop. If you are organized, you can also install cauliflower plants in August and October, but that means getting your seeds started beforehand. Cauliflower cannot survive our summer heat, so don’t waste your time with late maturing varieties. Seeds should be planted 1/2 inch deep in small containers and then transplanted when they look sturdy. Each plant will need an area 1-1/2 to 2 feet square to reach full size. Cauliflower (Brassica oleracea) uses a lot of water, so frequent irrigation is critical. As heads mature, protect them from sun damage by folding leaves over the flower.
While normally white, cauliflower varieties now come in purple, yellow, green, and orange. In the Bay Area, the best cauliflower varieties are:
There is also a crazy, spiky looking hybrid, Romanesco, that you may want to try.
Cauliflower pests and diseases
Cauliflower is susceptible to the same pests and diseases as other cole crops, such as broccoli and cabbage. For this reason, it is a good idea to avoid planting these crops in the same location, year after year. Crop rotation can break the cycle of many pests and diseases. This is called breaking the disease triangle. Row covers are very helpful when growing cauliflower. The most bare common pests of cauliflower include:
Powdery mildew, verticillium wilt, phytophthora root rot, clubroot, and damping off are common cauliflower diseases. Cauliflower plants are also subject to a condition called buttoning. Buttoning occurs when several days of excessive cold hit, causing plants to rush to create flowers that end up being significantly smaller than normal. Cute as a button doesn’t really fly in the world of cauliflower - though individual minis might look amazing on the Thanksgiving Dinner table! Anyway, excessive salt in the soil, competition from weeds, and insufficient water or nitrogen can also cause buttoning. Basically, if the plant thinks its on the verge of death, it will panic and produce tiny flowers, rather than no flowers at all.
Leave your cauliflower heads to mature fully before harvesting. When it is done growing, it will be fully open. Cut the plant off at soil level and leave the below-ground portion to feed the soil, worms, and soil microbes.
Slow and steady is the name of the game when growing cauliflower. Cauliflower is not easy to grow. These plants need nutrient-rich soil, regular irrigation, and the protection needed to develop into substantial plants before flower production begins.
Buffalo hopping from tree to tree? The image made me laugh, so I decided to make this pest the Garden Word of the Day.
Buffalo treehoppers (Stictocephala bisonia) get their name because they have a triangular head that looks like a buffalo in profile. Sort of. These native pests are only 1/4 inch long and bright green to brown. Because of the color and shape, they are difficult to see. Some individuals develop a horn-shape to the head that looks like a thorn. You can walk right up on one and not even know it’s there, until it leaps into the air and flies away.
Buffalo treehopper lifecycle
Every summer, male buffalo leafhoppers take to the trees and sing their tiny hearts out, but we can’t hear them. If we could, they would sound something like cicadas, or crickets. His song attracts females for the normal reproductive activities. Late summer through early autumn, females lay eggs using a blade-shaped ovipositor that cuts a series of slits in twigs and stems. Each cut may contain a dozen eggs. The next year, in late spring, nymphs emerge. They look like miniature adults, but with feathery spines. After several molts, they emerge as adults.
Damage caused by buffalo treehoppers
Well, they break off entire branches, right? Just kidding. These small pests begin their destructive behavior during the nymph stage when they drop to the ground and feed on grasses and herbaceous plants. As they mature, they begin feeding on many different fruit trees, particularly apple, pear, cherry, prune, and quince. They also feed on ash, hawthorn, elm, and locust, and a wide variety of herbaceous (non-woody) plants.
All stages of buffalo leafhopper are sap-suckers. They use piercing mouthparts to tap into the phloem for a sugar feast. This feeding results in a sticky sweet discharge called honeydew. Buffalo leafhopper damage is minimal, but big populations can cause problems with sooty mold fungi feeding on the honeydew.
Buffalo treehopper controls
Since they hop like crazy and can fly, control is difficult. A strong spray from a garden hose can dislodge insects from a specific host (for a while). While not nearly as interesting as trying to round-up a herd of forest-dwelling bovines, insecticidal soaps are effective. The best treatment you can give plants being sucked dry by buffalo leafhoppers is to hose them down to wash off the honeydew.
Calcium is a critical plant nutrient commonly found in alkaline soil. But that doesn’t mean your plants can get to it.
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.]
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 Bay Area soils contain abundant calcium. The optimal range is 1000-1500 ppm. My laboratory soil test results for calcium were 2705 ppm! A soil test, conducted by a reputable, relatively local 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 the Bay Area (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. Egg shells, agricultural lime, and calcium chloride sprays can be used to replenish depleted soils.
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.
Why do cucumbers curl into a C-shape?
Most cucumbers grow in a straight cylindrical shape. Except when they don’t. Sometimes, a cucumber will curve into a C-shape. This is called cucumber fruit curl. It is also called crooking. There are many causes for crooking. Which one is affecting your fruit?
Some sap-sucking cucumber pests can cause crooking. This form of crooking is usually irregular, having been caused by thrip, mite, and whitefly feeding. Aphids, scale, and mealybugs can also cause this type of deformity.
Cucumbers are heavy feeders. They need nutrient rich soil and regular feeding to produce a healthy crop of uncurled cukes. You can side dress the vines with aged compost. This also acts as a mulch, which helps stabilize soil temperatures and reduces the need for added water.
Think about how much of a cucumber is water. Add the water needs necessary to grow the vines and you will see that cucumbers need a steady supply of water. This means watering regularly and consistently. If you have placed mulch around the vines, add water whenever the top inch of soil feels dry.
Hot weather/incomplete pollination
Hot weather kills pollen. This can mean the female flower did not get enough pollen to produce a properly shaped cucumber. This normally causes stunting or lopsided development, but it can also cause curling.
Newly forming cucumbers are easily pushed around by stems, leaves, and flowers, as well as the ground itself. Also, if the flesh is damaged early on in development, the damaged side may grow more slowly, causing a curled shape.
How to prevent crooking
A curled cucumber is fine to eat.
We’ve all played with sand at some point. There were probably waves crashing in the distance, the smell of tanning lotion and sunscreen mixing with salty air. Sand gets everywhere and it can be used to make some amazing temporary castles and other works of art. It is also a component of soil.
What makes soil?
Soil is a combination of minerals, organic stuff (living and dead), liquids, and gases. The liquids and gasses, mostly air and water, move through large and small spaces called macropores and micropores, respectively. Soil can be mostly clay, mostly silt, mostly sand, or somewhere in between. Clay, silt, and sand classifications are more about particle size than actual material, but here’s the typical breakdown:
[Note: μm stands for micrometer, or micron. One micron equals one one-millionth of a meter.]
Soil texture and nutrient availability
If you live in Florida, you know all too well how difficult it is to keep nutrients and water in your sandy soil. This is because the spaces between the grains of sand are so big. At the other end of the spectrum, clay is made up of flat plates that tend to stick together, holding tightly to water and nutrients and making it difficult for plant roots to move through it. It very few macropores and micropores, which means drainage and aeration are common problems. This is also why it makes such nice pottery.
The Sand-Clay Myth
What is a gardener to do? Our intuition tells us that we can lighten heavy clay soil by adding sand. It sounds right. Sand has plenty of spaces! Putting the two together should give us a nice, happy medium, right? Wrong. Instead, the tiny clay particles fill in all the spaces around the sand grains, creating a soil that is even heavier than before!
Organic mulch to the rescue!
When I say ‘organic mulch’, I am not necessarily saying organic in the OMRI sense, although that is what I use. Organic mulch refers to mulch composed of materials that were or are alive: plants, animals, bugs, manures, that sort of thing. It does not include ground up plastics or other manufactured materials. When you incorporate organic mulch into sandy soil, you provide materials that can bind nutrients and water to the planting bed. The macropores become partially filled with water- and nutrient-retaining compost. When you top dress heavy clay soil with an organic mulch, earthworms, microorganisms, irrigation, and other actions will slowly incorporate chunks of non-clay material below the soil line, creating macropores and micropores for air, water, and plant roots to move through. Top dressing means you just leave the material on top of the soil, rather than digging it in. Digging clay soil is generally not helpful because of the smooth surface left behind by the shovel. When that surface dries, it can be impenetrable.
So, leave the sand at the beach or in your egg timer. If you have clay soil, organic mulch is what you want to use. You may be surprised to learn that sand is a non-renewable resource in high demand, due to our penchant for concrete. Apparently, creating sand take eons and we use a lot of it.
Salvia is tough and beautiful. The bees love it and you probably do, too!
This member of the mint family is one of those no-brainer plants here in the Bay Area. Composing the largest genus of mints, this group of plants includes the culinary favorite, sage (Salvia officinalis). Most ornamental salvias are referred to by their Latin name. The word salvia comes from the Latin word ‘salvere’, which means to feel well and healthy.
Salvias tend to be woody plants, which is one reason why they are so good at handling drought. Depending on the variety, they can be evergreen or deciduous, annual, perennial, or biennial. Like other mints, the stems tend to grow at angles to each other and are square. The flower spikes are the big attraction. They consist of a modified leaf, called a bract, and stalked, clustered flowers, called racemes or panicles. Flowers can be red, pink, yellow, or white, but the deep blueish-purple is my favorite. Hummingbirds, butterflies, and other beneficial pollinators love them, as well.
Weird salvia science
Unlike most mints, which have four stamens, salvia have a unique pollination mechanism that uses only two stamens and connective tissue (thecae) that create a lever action. Within male flowers, this lever action causes pollen to be dumped on any visiting pollinator. After the pollinator leaves, everything returns to its normal position. In female flowers, the same mechanism pushes the stigma to be in the same general area on the pollinator’s body, increasing the likelihood of pollination and fertilization (assuming they are the same size).
How to grow salvia
Salvias can be grown from seeds, seedlings, or cuttings, depending on the variety, once the last frost date has passed. Most salvias prefer full sun and good air circulation. An exception is the Japanese yellow sage (Salvia koyamae), which prefers shade and moist soil. If your soil is heavy clay, like mine, you will want to incorporate some aged compost to lighten it up before planting. Salvias will produce more blooms with regular feeding. You can also mulch around plants with aged compost for reduced moisture loss and slow-release feeding. If you prune your salvias before they bloom, flowering can be significantly delayed. Better to shear your salvias at a time of year when they are not flowering. And be sure to deadhead spent blooms the rest of the year to stimulate more flower production. While being drought tolerant, your salvias will need to be watered. Just wait until you notice some moderate wilting, to avoid common fungal diseases.
Salvia pests and diseases
Rust, powdery mildew, and leaf spot may occur, but they can often be prevented with proper water management [Read: avoid overhead watering]. Aphids and thrips will be the most common pests. [Aren’t they always?] Many salvias have hairs on leaves and stems that discourage many pests and grazers (and my chickens).
Whether you choose edible culinary sage, fragrant pineapple sage (Salvia elegans), the sacred white sage (Salvia apiana), or sturdy purple sage (Salvia dorrii), try adding some salvia to your landscape or garden today!
The heady aroma of summer nectarines and peaches means it’s time to be on the lookout for peach twig borers.
While examining my nectarines for ripeness, I spotted a reddish-brown larva with white bands undulating across a twig. Of course, I picked it up and dropped it in a little plastic bag and sealed it up tight, until I could look it up. That’s what I learned that even the nicest tree cage has its limits.
Peach twig borer description
The reddish brown larva I saw was relatively mature. They hatch out white with a black head. As they feed, the color darkens. Unlike other larval pests of peaches, the peach twig borer has white bands around its abdomen, though the bands are not always as obvious as they are in the photo above. The pupae are 1/4 to 1/2 inch long and brown. They do not have a cocoon. Adult moths are small, slender, and a mottled grey color, with fringed wings and a false snout. Oval eggs are yellowish-orange and laid on fruit, twigs, and leaves.
Peach twig borer control
Tachinid flies and braconid wasps provide natural controls. When that isn’t enough, you can spray environmentally sound insecticides, such as Bacillus thuringiensis (Bt) or spinosad, just as blossoms appear, for added peach twig borer control. Dormant oil can also be used in winter, when combined with the same insecticides, to kill off the overwintering larvae. The oil will not kill peach twig borers by itself. Pheromone traps can be used to interfere with mating and to monitor for these pests. Just be aware that hanging a pheromone trap can actually attract pests to your trees if handled incorrectly. Read the label.
So, as you check your nectarines and peaches for ripeness each summer, be on the lookout for these tiny pests. Also, add preventative treatments to your garden calendar while you’re thinking about it.
The summer song of crickets and grasshoppers provide many of us with a comforting reminder of childhood. If you are a gardener, your might hear those sounds with different ears.
Cousins to katydids and locusts, crickets (Gryllidae) and grasshoppers (Acrididae) are members of the Orthoptera family.
Both crickets and grasshoppers have a large head, long saltatorial* back legs, for jumping, a cylindrical body (pronotum), compound eyes, and a mouth able to bite and chew. They have two pairs of wings: the forewings (tegmina) and hindwings. Beyond those similarities, there are many differences:
Lifecycle of crickets and grasshoppers
Both species start out as eggs that were laid, in late summer and early fall, in the top 2 inches of soil, in clusters of 20 to over 100 eggs. In spring, these eggs hatch as nymphs, which begin feeding on nearby plants. When those food supplies are exhausted, they look for new places to feed, generally downhill from where they started. Grasshoppers will molt 5 or 6 times as they outgrow their exoskeletons, and crickets molt 8 or more times. There is no pupal stage, so these insects are said to go through incomplete metamorphosis.
There are house crickets and field crickets. Both are collective terms for several different cricket species. All of them feed on seeds and plants, along with grasshopper eggs, moth and butterfly pupae, flies, and spider sack lunches. House crickets (Acheta domesticus), sold as lizard food, are usually brown or tan, and one inch long or less. Field crickets are slightly larger than house crickets and they are usually black.
While there are over 200 different types of grasshoppers in California, only two cause significant damage: the valley grasshopper (Oedaleonotus enigma) and the devastating grasshopper (Melanoplus devastator). Most grasshoppers can fly.
Cricket and grasshopper damage
If their song didn’t tell you these pests had arrived, chewed holes in leaves certainly will. Grasshoppers and crickets will often hide out in nearby weeds and brush, so keeping those areas mowed can reduce the likelihood of a visit. On the flip side, maintaining a lush, green border may provide all the feeding that is needed by a few individuals. In any case, a single cricket will not do significant damage, but a large number of them can decimate a row of seedlings in just one night. Grasshoppers prefer green plants, so your lettuce, onions, carrots, corn, beans. melons, squash, and some annual flowers are vulnerable. Grasshoppers may also feed on citrus, avocado, and beets. In years with especially wet springs, cricket and grasshopper populations can explode. In these years, food scarcity makes all plants vulnerable.
Grasshopper and cricket controls
If these insects are causing damage in your garden or landscape, floating row covers, screened boxes, and cones are your best bet. Just be sure there are not any individuals hiding out in the mulch around your plants, or you may create a virtual Club Med for the pest! Birds, robber flies, and blister beetles feed on crickets and grasshoppers, or their eggs, and many parasites, bacteria, and fungi attack these garden pests. You can hand pick them if you are quick enough. Chickens are excellent at catching them, and it’s a riot to watch.
* For you word game and vocabulary nerds, saltatorial is an adjective that describes the legs of jumping insects.
Callus is what plants use instead of bandaids.
What are tree wounds?
Tree wounds can occur on purpose, by pruning, or by accident, from heavy winds or by being overladen with fruit. Most pruning cuts are relatively smooth. Accidental wounds tend to be jagged and the bark may be torn down the trunk. In these cases, the tree will benefit from the branch being cut back to a place where a flat wound is possible. This gets rid of insect hiding places and speeds the healing process for the tree. In both cases, interior tissue is exposed to the elements.
Traditional wound treatment
For decades, people have said that we should protect tree wounds with paint, pastes, and salves, which are generally petroleum based. The idea behind these treatments was that an open wound was vulnerable and that we could ‘help’ our trees by painting the cut surface with tar, asphalt, wound paint, or some other sealant. Instead of providing protection, these treatments actually seal in harmful bacteria and fungi, increasing the chance of disease or decay. Also, there are certain disease-carrying organisms that love to feed on or are otherwise attracted to the sealant!
It ends up, trees already know how to protect themselves. Just as our skin forms a callus in response to hard work and friction, trees create tissue over wounds to protect themselves from pests and diseases. The word ‘callus’ is from the late Middle English Latin word ‘callosus’ which means ‘hard-skinned’. Trees are able to generate their own ‘hard skin’ to cover a wound. If that process is interrupted with oil-based sealants, the internal processes of decay prevention may also be interrupted.
An exception to the rule
One case where wound dressing is a good idea is in regions (like ours) where oak wilt is a problem. If an oak in these areas is damaged or requires pruning, a sealant that contains insecticide and fungicide can prevent loss of the tree.
Why do the flowers keep falling off your tomato, squash, melon, and bean plants, and citrus trees?
This condition is called blossom drop. Blossom drop can be caused by several factors, most of which are perfectly normal. Others, not so much. Generally speaking, unfertilized flowers are kicked to the curb. Here are some species-specific causes of blossom drop.
Citrus June drop
Most citrus trees will produce far more flowers than they could possibly bring to maturity. When the tree decides it has enough fertilized flowers, usually around June, the rest are discarded. It’s nothing to worry about.
Cucurbit blossom drop
The first flowers on your melons, winter or summer squash, and cucumber are generally male. These drop naturally after a brief appearance. If female blossoms start falling off, it is usually because of thrip damage, poor soil fertility, environmental factors, or inadequate pollination. You can attract more bees and other pollinators to your garden by adding yarrow and bee balm. You can also allow onions, carrots, and fennel to go to seed. These plants will all provide pollen and nectar to beneficial insects that should increase pollination rates. If that doesn’t work, you can always try hand-pollinating.
Bean blossom drop
Temperatures over 90°F will cause bean flowers to abort. This can also occur with insufficient irrigation and poor air quality due to smog or fires. If you know your summer temperatures are likely to go over that threshold, try planting beans earlier or later in the season.
Tomato and pepper blossom drop
Tomatoes and peppers often drop their blossoms when environmental conditions are unfavorable. This might mean any of the following:
How to reduce blossom drop
Use these handy tips to reduce blossom drop in your garden:
The good news about blossom drop
Luckily, when environmental conditions cause blossom drop, most plants will simply try again, producing a second crop of blossoms.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.