Humus is the magical dark stuff of soil that helps plants grow. Or is it?
Microorganisms in the soil facilitate the decomposition of plants, bug bodies, and other living things in a process called humification. Humification occurs in the soil and in compost piles. Along with microorganisms, worms, nematodes, and other tiny critters help this transformation along. The black, rich, earthy smell from premium soil is the humus, or organic matter. (The black color is from carbon.)
When you add organic matter to the garden or compost pile, you are feeding the organisms that make nutrients available to your plants.
Fresh figs? Yum!
Figs are believed to be the very first human attempt at agriculture, even before barley, wheat, and legumes, over 11,000 years ago. In Aristotle’s day, farmers and scientists had some interesting ideas about wild fig trees and farmed fig trees: it was believed that tiny wasps flew from the wild (fruitless caprifig) trees to the farmed female (fruited) trees to help them hang on to the fruit! If that weren’t interesting enough, did you know that figs are not actually fruit at all? Read on!
These resilient trees grow very well in the Bay Area, thriving in our hot, dry summers and cool, wet winters. Originally from the Middle East and western Asia, figs are now found all around the world (except Antarctica, of course!) and with good reason. Forget the bagged, dried version of this healthful snack. Plucking a freshly ripened fig from the tree and taking a bite is heavenly. If you decide you have too many figs to eat fresh, you can always dry your own!
How figs grow
Figs (Ficus carica L.) are deciduous trees or shrubs that can reach over 30 feet in height. They tend to send out multiple trunks that create a tree that is wider than it is tall. Fig wood tends to be weak, so pruning may be needed to keep the tree structurally sound, but not necessarily. Their wide, fragrant leaves provide nice shade, but you will want to avoid the sap as it contains a form of latex that can irritate your skin. Fig trees prefer sunny, well drained locations and they are quite drought tolerant. Figs can also grow well in poor, rocky soil.
Figs reproduce several different ways. Naturally, birds and mammals that eat the fruit end up spreading seeds. Fig trees also tend to send out aggressive roots, stolons, and suckers that can be used to create new plants. You can also bend a low-growing branch down to the ground, or a container, and hold it down with a rock or some wire. After roots emerge, the new growth can be separated from the parent plant. Most fig trees are purchased as bare root trees.
Botanically, fig trees are gynodioecious, which means they have hermaphrodite flowers and female flowers on separate plants. Unless you buy a self-pollinating variety, you will need more than one tree. My self-pollinating fig produces more and more fruit every year. Fig pollination is usually completed by tiny specialized wasps called Blastophaga psenes. (Aristotle was partly correct!) Fig flowers are hidden clusters found inside a hollow structure called the syconium. The fruit, which is not technically a fruit, is actually a scion, or infructescence. An infructescence is a fruit head made up of the ovaries from a flower cluster, often called a ‘false fruit’ or a ‘multiple fruit’, depending on the presentation. Within each fig “fruit” are several one-seeded fruits called druplets. Pineapple, wheat, and corn are other examples of infructescence.
How to grow figs
Fig trees can be grown in large containers, but you will want to take advantage of their deep roots. Planting fig trees in the ground practically eliminates the need for irrigation. Like grapes, fig trees have deep roots that allow them to get most of the water they need from the soil’s saturation (or phreatic) zone, so irrigation is rarely needed once plants are established. UC Backyard Orchard provides an excellent list of fig cultivars here.
Fig pests & diseases
Thrips, ants, green fruit beetles, dried fruit beetles, gophers, and birds are the only serious pests. Ants can be thwarted with a sticky barrier around the trunk. I have always found that netting is invaluable for protecting my fig crop. Euryphid mites may not cause significant damage but they can carry fig mosaic. Sunburn protection is a good idea. Simply paint a 50:50 mix of water and white latex (not enamel) paint on exposed surfaces.
Some fig varieties produce two crops a year. The first, or ‘breba’ crop, occurs in mid-summer and the second, main crop ripens in late summer or fall. Be sure to allow figs to ripen on the tree. They will not continue to ripen once picked.
Add figs to your foodscape for decades of delicious fiber and welcome summer shade!
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.
Carrots are not just for bunnies!
Healthy, delicious, and more colorful than ever, you can grow carrots that are white, purple, red, and yellow, along with the familiar bright orange.
Carrots are related to fennel, celery, cilantro, dill, cumin, and parsley, all members of the Apiaceae or Umbelliferae family. These plants all have umbrella-shaped flower clusters that attract many beneficial insects. Carrots are biennial plants grown primarily for their taproots (the tops and seeds are edible, too).
How carrots grow
Carrot flowers change their gender as they develop. This means that a single umbel, or flower cluster, will contain both male and female umbellets at the same time, with the older female flowers on the outer edges, with male stamens closer to the center. After fertilization is complete, the umbel starts to curl upward, creating a bird nest shape. If allowed to grow through a winter and experience vernalization, your carrot plants will produce seeds for yet another crop. Selective harvesting can make your carrot patch a perennial food source.
Why grow carrots?
True to their ancestral home of modern day Iran and Afghanistan, carrots prefer growing in sandy soil. Our Bay Area clay is probably the worst soil for growing carrots. Plus, carrots are not exactly the most expensive produce in the grocery store. So, why bother? For the same reason we are compelled to grow our own tomatoes, peas, berries, potatoes, and more ~ it tastes better, we have more control over what goes into our food, and we reduce our carbon footprint.
Carrot body & color types
Carrot varieties are categorized by both color and shape. Carrots are classified as Eastern or Western, based primarily by color. Our common orange carrots are Western, while the more colorful yellow, purple, and crimson varieties are Eastern. Both Eastern and Western color types are then divided up by shape:
The shorter, stubbier, blocky shapes perform best in shallow soil (or containers), while the longer, slender growth carrots need more depth to grow well.
How to grow carrots
Carrots take 90 to 120 days to mature, depending on the variety. Carrots prefer full sun and cooler temperatures, but they can be grown in partial shade. While our clay soil is not the best thing for carrots, our alkaline pH is. Carrots prefer a pH range of 6.3 to 6.8. Carrots do not compete well with rocks and stones, so they are better suited in our area to raised beds. Carrot seeds are really tiny and can be difficult to space properly. One way to get around this is to stir together some carrot seeds, radish seeds, and some light soil or sand. Sprinkle this mixture over the planting area. The radishes will grow far more quickly than the carrots, creating automatic succession planting. It will also create space for the carrots. Once they emerge, carrot seedlings should initially be thinned to one inch apart. As you begin to see which plants are thriving, thin again to 4 inch spacing by cutting off the plants to be removed at soil level. This avoids disturbing the roots of remaining plants. Be sure to compost or dispose of these cuttings, rather than leaving them on the soil, to avoid attracting carrot pests.
Carrot pests & diseases
Being a root vegetable, most carrot pests are underground. Vegetable weevils, root knot nematodes, wireworms, flea beetles, and root maggots can damage your crop. Alternaria leaf blight has been known to wipe out entire crops. Being underground, these pests are generally not impacted by the use of pesticides. You can see a full list of common carrot pests and diseases on the UC IPM page on carrots.
- Carrots, combined with turnips, are in the Top Ten of important global vegetable crops, with 45% being grown in China. Only 3% of the world’s carrot and turnip production is domestic.
- Unwashed carrots can be stored for several months in layers of sand, or a 50/50 mix of sand and sawdust.
- Adding manure to carrot beds can cause split taproots.
- According to Wikipedia, “The roots contain high quantities of alpha- and beta-carotene, and are a good source of vitamin K and vitamin B6, but the belief that eating carrots improves night vision is a myth put forward by the British in World War II to mislead the enemy about their military capabilities.”
- This last one just a theory of my own. The Latin name for carrots is Daucus carota sativus. Daucus carota sounds an awful lot like ‘Doc’ and ‘carrot’ to me. Switch them around and I hear, “What’s up, Doc?” Coincidence? Maybe. But, maybe not…
Give carrots a try in your yard or on your balcony and let us know what you think in the comments section!
Why grow hazels?
The obvious reason for growing a hazel bush is the delicious nuts. Hazelnut plants can produce food for 80 years! Hazelnut shrubs also make excellent, drought tolerant anchor plants in the landscape. Traditionally, hazels were planted as hedgerows between properties and grazing fields. They were frequently coppiced, or cut to ground level to stimulate new growth, to provide long, slender poles for basket-making and wattle and daub fencing.
Some scientists group the hazels with birch trees, while others claim hazels are their own grouping. All hazels are from the Corylus genus and all of their nuts are edible. Worldwide, there are 14 to 18 species. Only two species are native to North America, with one local variation:
How hazels grow
Unlike most plants, hazelnuts bloom and pollinate in winter. Yellow pollen-crusted catkins release their bounty to the wind, which carries it to tiny red flowers. There, the pollen stays dormant until summer. That’s when the nuts start to form.
Hazels are monoecious, or hermaphroditic, having both male catkins and female flowers on the same plant. Catkins are hanging flower clusters that contain pollen. Hazelnuts are self-infertile, which means you will need more than one plant to produce a crop of edible nuts.
Members of the hazel family are all deciduous. Some are trees and some are suckering shrubs. These suckers can be used to to create new shrubs elsewhere on your property or given to family and friends to start their own. Commercially, the suckers are generally removed and the shrub is trained into a tree form, to make management and harvest easier. What you do with yours is entirely up to you, but it is nice to have options!
How to grow hazelnuts
If you have access to suckers, use them! Otherwise, you can plant nuts in loose soil and water occasionally. Germination rates and speed can be increased by scarification, or scoring the outer layer of the nut. Once seedlings are 12 inches tall, they can be transplanted to their permanent location. They will begin producing nuts in their 3rd or 4th year. These nuts grow in clusters called burrs.
Hazels are shallow-rooted plants that cannot tolerate soggy ground. They are drought tolerant and require little effort on your part, once they are established. Only during the peak of California summers do they need any irrigation.
Hazelnut pests and diseases
One very serious threat to hazelnuts has kept them from being grown commercially in the Eastern U.S. It is called eastern filbert blight. Our native species are resistant, and some are immune. This disease has recently made its way west to Oregon and California. Pests include bud mites, jay birds, and squirrels. Ads claim that giant eye floating balloons are a good way to keep birds out of fruit and nut trees, but I was unable to find any research that verified those claims.
Hazelnut harvesting begins in autumn, as the leaves and burrs turn brown. Remove nuts from the burrs and lay them out in a single layer, in a protected area, to dry for a few days. Roasting makes it easy to remove the inner paper, which can taste bitter, and it brings out that rich hazelnut flavor that we all know and love!
Guttation may look like dew, but it is actually a plant’s way of getting rid of excess water.
Dew normally accumulates on plant surfaces when there is enough moisture in the air and temperature differences that create different rates of evaporation and condensation. Guttation is closer to sweating.
Under normal conditions, plants close the tiny holes, or stoma, found on the underside of leaves. These stomata are used in respiration. When there is too much water in the soil, water pressure builds up in the roots. This forces xylem sap out of tiny leaf edge structures called hydathodes. When this xylem sap dries on a leaf, it often leaves a white crust. This crust is mostly sugars and potassium.
Research has shown that corn seeds treated with neonicotinoids create guttation drops that contain active ingredients with insecticidal properties. These chemicals are posing a serious threat to native bee populations. As bees drink these sugary droplets, they are poisoned and die within minutes.
Infiltration rate is a measurement of how quickly water can enter soil.
Infiltration rates are reported as the depth water (in millimeters) can reach within one hour. For example, an infiltration rate of 10 mm per hour means that a 10 mm layer of water on top of the soil will take one hour to soak in. Understanding the infiltration rate of your garden or landscape can mean the difference between irrigation and flooding.
Soil types & infiltration
When soil is extremely dry, it won’t absorb water at all because it becomes hydrophobic. Before that point is reached, water is absorbed quickly in what is called the initial infiltration rate. It happens quickly because the macropores in the soil contain only air, giving the water plenty of places to go. As the pores begin to fill, absorption slows down to a steady rate called the basic infiltration rate. According to the Food and Agriculture Organization of the United Nations (I never knew there was such a group until today!), different types of soil have different basic infiltration rates:
Clearly, taking an infiltration test can help you have a better understanding of what type of soil you have. It also helps you to select plants that are best suited to your soil.
Benefits of better infiltration
Understanding and amending the infiltration rate of your soil can provide many benefits:
How to conduct an infiltration field test
Generally speaking, most of these tests are done with specialized equipment. You can, however, follow these steps to perform a modified version that will give you useful information:
Another testing method you can try only requires a shovel and a watch:
If your soil is like mine, compacted heavy clay when we moved in, adding organic material is the best way to improve the infiltration rate. If you plan on installing a rain garden, checking the infiltration rate is critical. Standing water can drown even the healthiest plant, given enough time.
Help your garden and your landscape with improved permeability and infiltration rates. Your plants will be healthier, more beautiful, and more productive.
Honeydew sounds delightful, doesn’t it? To some, its sugary sweetness is like manna from heaven. To a gardener, honeydew sets the stage for countless fungal diseases and pest infestations. Honeydew is aphid poop.
What is honeydew?
When aphids feed, they do so by sucking sap from plants. Sap has a lot of sugar in it and the sap within a plant is under pressure. When an aphid pushes its sharp mouthparts into a plant, the sap is actually pushed into the insect! The pressure is so intense (from an aphid’s point of view) that the sap is often pushed all the way through the insect’s body and falls onto the plant. This is honeydew. Eugenia psyllid, whiteflies, treehoppers, leafhoppers, mealy bugs, and some scale insects also produce honeydew. If you notice a trail of ants leading to a soft scale or armored scale infestation, it’s all about the honeydew.
Honeydew as food
Ants love honeydew. They love honeydew so much that they actually farm aphids! Ants herd sap-sucking insects to keep them close to ant nurseries, They will protect aphids from ladybugs, lacewings, and other beneficial predators. Ants even milk sap-suckers for their high energy poop by stroking their bellies! Some bees and wasps collect honeydew and use it to make a strong, dark honey called honeydew honey.
This would all be fine except that many of the insects who create honeydew are also vectors for diseases, such as huanglongbing, or citrus greening. As ants feed on the honeydew, they also spread disease. Any honeydew that is left on plant surfaces uneaten provides the perfect habitat for fungal diseases, such as sooty mold. Since ants are the problem in this cycle, using sticky barriers to block their way is the easiest solution.
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.
Self-pollination occurs when the flower of one plant can pollinate a flower on the same plant.
Nearly every piece of fruit we eat (and many fruits that we call vegetables) would not exist without pollination. When creating a foodscape, space constraints can be a deciding factor in plant selection. While plants that cross-pollinate, those that use flowers from two different plants of the same species, often produce bigger and better yields, botanists have nurtured many self-pollinating varieties that can be used on balconies, windowsill gardens, and small yards.
How does pollination work?
Pollination refers to the transfer of pollen (sperm cells) from the anther to the stigma of a flower (angiosperm) or the ovule (gymnosperm), and the resulting fertilization of an embryo. Plants that use cross-pollination expend a lot of energy attracting pollinators. They use bright, colorful flowers, sugary nectar, and sweet aromas to attract the beneficial insects and bats that carry genetic information from plant to plant. Plants that rely on self-pollination tend to have smaller flowers because most of the pollen transfer occurs by falling onto the stigma as the flowers close. Wind, bees, moths and butterflies, birds, bats, and even rain may also play a part, but infrequently. If self-pollination occurs within the same flower, it is called autogamy. When it occurs between different flowers on the same plant it is called geitonogamy.
Pros and cons of self-pollination
The most obvious advantage of planting self-pollinating varieties is that you will only need one of them. It also means you can get a harvestable crop without the help of bees or other pollinators, which might be in short supply in your area. The disadvantage of self-pollination is that it limits genetic diversity and may reduce overall plant vigor. Just as inbreeding in mammals increases the chance for disease and deformity, plants can respond the same way.
Edibles that self-pollinate
Most sour cherry, peach, nectarine, citrus, and pear trees are self-pollinating. If you shop around, you can find self-pollinating plum, almond, and avocado trees, as well as some grape varieties. Many vegetables self-pollinate, including peppers, peas, beans. tomatoes, and eggplant. Fruit cocktail trees are one way to reduce space requirements while still taking advantage of self-pollination. These trees have several varieties grafted onto the same root stock, so they are technically self-pollinating.
Why is this important?
Understanding which plants self-pollinate can help you select the best plants for your garden. Fruit and nuts trees, in particular, are an investment of time and money. If you only have room for one, you have to make sure that it can self-pollinate if you are going to get a harvestable crop.
Be sure to read plant labels and get your plants from reputable suppliers. It can take a year or two to learn that a tree advertised as self-pollinating was a marketing scam and then it is pretty damn hard to dig it out and start over.
Lucious fresh blueberries in California? Yes, you can!
While blueberries traditionally grow in colder climates, there are varieties that grow successfully in warmer temperatures.
There are three main types of blueberry plant: southern highbush, northern highbush, and rabbit eye. Southern highbush and rabbiteye varieties often perform well in higher temperatures. Generally, the northern highbush types need more chilling hours than my garden can provide. Even when they do grow, the fruit often lacks good flavor. Also, the northern highbush types will take longer to start producing fruit in warmer areas. Two popular southern highbush varieties for warm areas are Southmoon and O’Neal. Santa Clara County Master Gardener offer this list of blueberry plants that perform well in warmer climates.
Prepare for planting
Blueberry plants are nearly always sold as 1-gallon yearlings.These young plants will benefit from 7 to 10 days of acclimation, or hardening off, after growing in a greenhouse. Be sure to keep the soil moist but not soggy. The root system is a hairy ball that should never be allowed to dry out completely. If it does, the plant dies. At the same time, too much water can set the stage for fungal disease. Yeah, I know - picky, picky, picky! Of course, once you start picking scrumptious blueberries off your very own edible hedge, you’ll realize it’s well worth the effort.
How to grow blueberries
So, choose the best varieties for your microclimate and taste. Even though most blueberry plants are self-pollinating, you will get a substantial increase in both fruit quantity and quality through cross-pollination with multiple plants. Plants should be spaced 4 to 6 feet apart. Blueberries perform best with 6 to 8 hours of sunlight each day, so select the site accordingly. Good drainage is important, too, so be sure to amend the planting area with plenty of aged compost. This is critical in area with compacted clay soil. Plants should be placed with the crown at soil level. Since blueberries have a shallow root system, you can help them stay happy and healthy by mulching and watering regularly in summer. Blueberries can also be grown in containers.
Blueberries seem to prefer ammoniacal nitrogen based fertilizers over nitrate based. I have heard tell that blueberries do not take up the nitrogen in nitrate based fertilizers. Too much nitrogen can burn blueberry plants, so do not feed until leaves have emerged, and then feed sparingly.
Acidifying blueberry soil
Blueberries prefer a soil pH of 4.5 to 5.5, while most San Jose, California soils are 7 or higher. This means that you may want to acidify your soil. To really know what you are working with, have your soil tested by a reputable lab. Over-the-counter test kits and strips are unreliable. Unless you want to spend hundreds of dollars on lab equipment, lab tests are really the only way to go. If it ends up that acidification is needed, try amending the soil with coffee grounds, citrus rinds, or oak leaves. You can also buy commercially available acidifiers. Keep in mind that changing pH is a slow process and that it requires regular monitoring.
Blueberry pests and diseases
Citrus thrips, katydids, light brown apple moth, masked chafer, blueberry bud mites, cranberry weevils, scale insects, Pacific flathead borers, plum curculio, sharp nosed leafhoppers, spotted wing drosophila, span worms, and Asian longhorn beetles will all try attacking your blueberry plants, but birds will probably cause the most damage. Personally, I built cage frames around my blueberry bushes and stapled netting to the frame. It works very nicely. Common blueberry diseases include twig blight, canker, stem blight, mummy berry, anthracnose, and blueberry stunt disease. Removing dead or diseased canes and treating with dormant oil can go a long way toward protecting your blueberry plants.
Your blueberry plants can live for 20 years, producing fruit after the third year.
Bok choy is a type of Chinese cabbage. Rather than forming dense heads, these varieties have delicious dark green leaf blades and crisp white stalks.
Cool season crop
Cousin to broccoli, cabbage, and cauliflower, Bok choy (Brassica rapa) is a cool weather crop. This means it can be planted in the Bay Area in February, March, and April, and again in September and October. Your microclimate may vary.
How to grow bok choy
Bok choy can be seeded directly in the ground, but starting the seeds in little pots, 2 to 4 weeks before it’s time to put them in the ground, seems to have a higher success rate in our area. Bok choy needs loose, rich soil. This makes it a good candidate for raised beds and containers, where you have more control over soil structure. Seeds should be planted 1/4 to 1/2 inch deep, and they should germinate in 7 to 10 days. After seedlings are 4 inches tall, they can be very gently transplanted to their garden location. Place seedlings 6 to 10 inches apart. Plants take only 45 to 50 days to reach maturity, so this is a pretty rewarding crop.
Healthful bok choy
Nutritionally speaking, bok choy is 95% water, but a single serving (100 g) provides more than 20% of the Daily Value of vitamins A, C, and K, and all for only 13 calories! Research has shown that eating bok choy, which contains chemicals called glucosinolates, which may reduce cancer risk.
Bok choy grows quickly, requires little care, and it takes well to salads, soups, and stir-fry.
Treehoppers, or thorn bugs, are wedge-shaped, sap-sucking, jumping insects found everywhere on Earth except Antarctica.
All treehoppers have conspicuous eyes and modified dorsal plates (pronotum), commonly called helmets. These helmets are believed to have evolved from what was once a third set of wings. Frequently, these helmets look like camouflaging thorns. [Many thorn-shaped tree hoppers will shimmy around to the opposite side of a stem as you walk by!] Globally, the range of treehopper shape defies description.
While most colors are drab, you can also find neon stripes, spots, and squiggles. There are treehoppers that look like ants walking backwards, space ships, curls of dry wood, flower petals, and even bird poop! Nymphs can be equally bizarre, donning such crazy outfits as a puffy cotton bodysuit, a head piece of neon spikes, or a tail made out clusters of el-wire. (Check out more pictures of treehoppers at Mental Floss.) Most treehopper nymphs have Mandelbrot spikes on their helmet. North American treehoppers are far less flamboyant. They tend to be green or brown, smooth-bodied wedges, 1/2 inch long or shorter. In the greater Bay Area, we have Oak treehoppers (Platycotis vittata) and Buffalo treehoppers (Stictocephala bisonia). Oak treehoppers are commonly found in spring, in the lower branches of oak, birch, and other deciduous trees. Buffalo treehoppers can be found in apple trees.
Ants and treehoppers
Just as ants protect and farm aphids, they provide similar mutualistic services to treehoppers. Being sap eaters, treehoppers poop out a sugary waste called honeydew. Ants love to eat honeydew. The relationship is so intimate that treehoppers can send out an alarm when they are attacked and ants will come to their rescue! Some species of treehoppers have the same type of relationship with certain wasps and even geckos!
Eggs are normally inserted into the cambium layer of stems by a female’s saw-like ovipositor. Sometimes, eggs are laid on leaf surfaces. Many plants are damaged more by egg laying than by treehopper feeding. When eggs hatch, the nymphs are usually too small to produce enough honeydew to attract ants. Some mama treehoppers will stay close by, using her honeydew to attract protective ants. Unlike adults, nymph treehoppers have an extendable anal gland used to deposit honeydew further away. These tubes tend to be longer in solitary treehopper species. I wouldn't bring it up except that this appears to be an important evolutionary mechanism for avoiding infection by fungal diseases, such as sooty mold.
Damage and host plants
Treehoppers have sharp beaks they use to pierce grass blades, twigs, canes, leaves, and branches. As sap oozes out, treehoppers lap it up, taking advantage of the high sugar food source. As treehoppers feed, they can act as vectors for disease. In fact, some treehopper diseases attack both the pests and the host pants, growing in the treehopper’s salivary gland! Predominantly a tropical pest, treehoppers can still damage your grapes, celery, tomatoes, legumes, avocado, and papaya in North America. Their cousins, the leafhoppers, cause far more damage to our local gardens.
In nature, treehopper eggs are frequently parasitized by fairyflies (Mymaridae) and Trichogrammatidae. For this reason, it is better to avoid broad-spectrum pesticides. Horticultural oils can be used to prevent eggs from hatching, and insecticidal soaps can be used to treat heavy infestations of nymphs and adults.
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, 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.
Annuals, perennials, and biennials - what makes them different isn't as clear as you might think.
Put simply, annuals are plants that complete their lifecycle in a single year. They tend to be more colorful than longer-lived biennials and perennials. Let’s find out why.
Genetic survival strategies
Plants are all about reproduction, and they have different strategies to ensure the survival of their genetic information. While perennial plants invest energy into maintaining individual plants over time (and some can live for thousands of years), biennials use the first year to collect resources and the second year to produce seeds. Annuals go from seeds to seedlings to mature plant to seed production in a single growing season, and then they die. This means that they do not have the luxury of missing a chance at being pollinated. Brighter, more fragrant flowers increase those chances. Other annuals, especially those found in the desert, spend most of their life as a seed. These plants, ones that go from seed to seed in only a few weeks, are called therophytes. One big advantage to being an annual is this lifecycle interrupts many pests and diseases that might otherwise wipe out a species.
Annuals as food
Many of our food crops are annuals that must be replanted each year: corn, peas, beans, melons, squash, and most cereal grains are annuals. Some biennials are grown as annuals, for convenience sake, or because they cannot tolerate locale microclimates. These plants include celery, parsley, and carrots. Other common edibles, such as tomatoes, sweet peppers, and sweet potatoes, are actually perennial plants, but most gardeners treat them like annuals. Under the proper conditions, these plants can continue producing food year round for several years.
Seeds from annuals
As your annual plants end their growing season, you can prepare the the next year by collecting seeds. Choose seeds from the strongest, healthiest, most flavorful produce, and dry them out of direct sunlight. Some seeds may need chilling hours. Other seeds may need a short trip to the freezer (such as beans) to kill off any internal pests.
Sweet, flavorful apricots, warm from the sun, freshly plucked from the tree, are one of life’s perfect moments. In my opinion, they rank right up there with their cousins, peaches and nectarines, as foods that define summer.
Apricots (Prunus armeniaca) are also related to cherries, plums, prunes, and almonds. If you look at the pits, you will see the similarities; they are all stone fruits. While dwarf varieties can be grown in large containers, apricots prefer being planted in the ground, in a sunny location. Plant an apricot tree and you will be treated to lovely spring blossoms and delicious summer fruit. The trunk will, over time, develop a striking gnarled look, too.
How to plant an apricot tree
Unlike apples, pears, and other members of the rose family, apricots grown from seed have a higher chance of being similar to the parent plant. While there are no guarantees, you can take the pit from an apricot, cover it with an inch of soil, keep it watered and in a sunny location to start your homegrown apricot tree. For faster results, bare root stock can be used. Apricot bare root stock should be planted in January or early February, here in the Bay Area. Apricots prefer well-drained soil, but they can tolerate some clay. Before placing your apricot rootstock, be sure to amend the site with lots of compost, to help it get a healthy start. Also, if you have heavy clay, be sure to score the edges of the planting hole. Smooth clay is an impenetrable barrier to young roots.
How to select an apricot tree
When selecting rootstock, be sure to match the variety with your microclimate. Chilling hours vary by species, as does disease and pest resistance. If your tree does not accumulate enough chill hours, you won't get any fruit. Most apricots are self-fertile, so it is usually not necessary to have more than one tree. Contact your local Cooperative Extension Office for the best varieties for your area. The following varieties are good choices for San Jose, California:
Apricot tree care
Each fall, before the rains begin, prune away 20% of last year’s growth, along with any dead, diseased, or poorly placed branches. This will allow more light to reach interior branches, stimulate new spur development, and improve the overall health of the tree. [Spurs are flower-bearing buds]. Spray for pest and disease control in winter and again in spring. Feed mature apricot trees 1 to 2 pounds of urea just before spring irrigation is begun and water it in thoroughly. Young trees should be given the same amount of urea, but spread it out in quarters over a 4 month period. As fruits reach 1/2 inch in diameter, they should be thinned to one fruit every 4 to 6 inches, for the best size and flavor. This also reduces the likelihood of pests and diseases.
Begin irrigating in spring by watering every 2 or 3 weeks to a depth of 18 to 24 inches. This is one of those times where guessing isn’t good enough. I use my soil sampler, but you can use a trowel to gently dig down to the appropriate depth. If the soil isn’t moist, you need to figure out where the water is going and redirect it. Many times, hydrophobic soil will push water away. Watering more slowly can avoid this problem.
Apricot pests and diseases
Peach twig borers, Fuller rose beetles, San Jose scale, mites, and aphids are common apricot pests. Apricot is susceptible to Eutypa dieback, so pruning should only be done during summer, unlike other trees which are pruned during winter dormancy. Autumn and winter sprays of dormant oil, fixed copper, or Bordeaux mixture, as well as the use of sticky barriers, can help protect your apricot tree against other pests and diseases, such as brown rot, bacterial canker, shot hole disease, and crown gall. Despite these fungal diseases, do not use sulfur on apricots.
A little space in your yard or on a balcony is all that is needed to start growing fresh apricots - give it a try!
Bats in the garden? Let’s hope so!
While bats can be vectors for diseases, such as rabies, more often than not, bats are a gardener’s friend. In just one afternoon, you and your kids can build a bat box that just might attract these garden predators for many years to come.
It is estimated that a pregnant or nursing bat will consume 2/3 of their body weight in insects each night. According to UC Division of Agriculture and Natural Resources (UCANR), bats protect over $23 billion of American crops each year. That’s a substantial impact for a flying mammal that weighs in around 1/3 of an ounce!
A little bat history
Bats started flying around over 50 million years ago, after the dinosaurs died off, but we know surprisingly little about them. One thing we do know is that their numbers are in serious decline. According to the U.S. Forest Service, “Currently 56% of the bat species present in North America are listed or being considered for listing under the Endangered Species Act.” Loss of habitat and human prejudice are mostly to blame.
Contrary to popular myth, most bats are not vampires. Vampire bats are only found in Latin America and they prefer the blood of animals to that of humans. Most bats are insectivores. The rest of them eat fruit, mice, or other small mammals. These fruit eaters are frequently considered a “keystone” species. This means that the plants which rely upon bats for pollination and seed dispersal are critical to the survival of other animals and birds. Bats are the major pollinators of agave. You know, the stuff used to make tequila. And the Mexican Free-tailed bat is responsible for pollinating most of the sugarcane used to make a well known brand of rum. [Take a closer look at the label and you will see the bat!]
Many years ago, while volunteering at Woodland Park Zoo in Seattle, I worked with fruit bats in the Nocturnal House. Larger than our native bats, the zoo’s fruit bats were sweet tempered, gentle, and loved being scratched around the face and ears. Not what you expected, right?
Scientists are still debating bat classification. One camp believes that all bats evolved from a single mammalian flying ancestor. Others classify bats into two groups: megabats and microbats. Megabats are found in Asia, Australia, Africa and the South Pacific. The largest megabat species has a 5’6” wingspan! This group evolved from lemur-like animals and they do not have the gift of echolocation. Microbats are found everywhere except Antarctica and are believed to have evolved from shrew-like animals. Microbats do use echolocation to navigate. All bats have an excellent sense of smell. Worldwide, there are 925 bat species. There are 23 to 50 species of bat found in California, depending on who you ask, spread out between three different bat families:
There are 16 species in the greater Bay Area. The most commonly found include:
Benefits of bats
All bats in the Bay Area are insectivores. A single bat can consume hundreds of insects in an hour and they may live for 5 to 30 years, depending on the species. While research has shown that bats do not have a significant impact on mosquito populations, they do help control beetles, moths and moth larvae, wasps, ants, and cockroaches.
Bats generally mate in fall, but females hold onto the sperm for several months, until conditions are more favorable for their young. Then conception occurs. A single pup is born each year around May or June, blind and hairless. The pup is diligently cared for until it learns to fly after a month or two. Young bats will try to eat pretty much anything. Unfortunately, they do not like banana slugs. Like dolphins, microbats are believed to use the Earth’s magnetic field to find their way. Many microbat species migrate over 1,000 miles each year, the same way salmon do, returning to their place of birth.
Each year, many bat pups starve to death when humans try blocking bats from entering, not realizing that the young are already inside. Result, less bats in the world and dead bats in your attic. If you really must get rid of bats, hire a professional. A better choice would be to build your own bat house and lure your guests away from your home while taking advantage of their voracious appetite for garden pests. That being said, bats can carry diseases that are dangerous to humans, so wild bats should NEVER be handled. This is for your safety and theirs.
How to build a bat box
Bat boxes are simple to make. Since bats prefer tight, skinny spaces, a bat box is, for the most part, several sheets of wood separated by thin boards. To make the most out of your bat house, be sure to avoid these common problems:
Bat Conservation International has the best bat house plans I have seen. When placing your bat house, keep in mind that those hung on poles or in trees are almost never used because they get too cold at night, or opossums and raccoons will eat the bats. Chimneys work well, but then there’s the issue of guano (bat poop) accumulation. Guano should never be handled without skin and respiratory protection. Guano may contain lots of nitrogen, phosphate, and potassium, like most fertilizers, but it can also make you really sick. It is used to make gunpowder…
Dill’s delicate fronds and distinct aroma make it a useful addition to your landscape.
Dill (Anethum graveolens) is an herb that is related to celery and is known for elevating pickled cucumbers, asparagus, garlic, and green beans to new heights. Did you know that dill oil, extracted from seeds, stems, and leaves, is used to make soap?
How dill grows
Dill can reach a height of 2 to 4 feet, making it only slightly smaller than fennel, which has a similar feathery growth. Dill’s leaves are wider and more firm than fennel’s. Flowers are white or yellow umbels (think umbrella) that attract many beneficial insects. Dill seeds look like tiny brownish-grey orange slices. Once dill begins producing seeds, leaf production is over and the plant will soon die. Worry not, dear gardeners! Dill reseeds itself so easily that you are nearly assured of a new crop from seeds that fall to the ground. To collect seeds for kitchen use or future crops, remove seed heads and hang upside down over a bowl or in a pillow case. Seeds will fall when they are mature and the flower head can be added to the compost pile to feed next year’s generation!
How to grow dill
Dill is a biennial that is normally grown as an annual. Dill does not transplant well, so site selection is your first step. Dill prefers lots of sun, though partial shade can be tolerated. Shadier sites will result in less bushy plants. You can easily grow dill in a container that is at least 12 inches deep. This will make room for dill’s taproot. (‘Fernleaf’ is a dwarf variety best suited for containers.) Seeds should be planted 1/4 to 1/2 inch deep and the soil keep moist until seedlings emerge. Seedlings should be thinned to 12 inches apart. Once plants are established, the soil should be allowed to dry out between waterings. Side dressing plants with aged compost during the growing season will provide important nutrients. (Side dressing simply means dumping an amendment around a plant and watering it.)
Dill pests and diseases
Dill has very few pests, thanks to the volatile oils that give it its flavor. Tomato hornworms and parsley caterpillars may be seen and can be handpicked. Bacillus thuringiensis (Bt) or insecticidal soap can be used to treat severe infestations. Dill is relatively disease-free.
So many dishes will be enhanced by dill leaves, simply snip off what you need. You can also dry dill leaves for later use by placing cut leaves between cloth napkins or paper towels, laid on top of nonmetallic screens, and storing in an airtight container. Dill leaves can also be frozen. You can keep harvested leaves fresh by wrapping them in a damp paper towel and refrigerating them for up to a week in a sealable container.
Growing dill for yourself is easy and rewarding! Give it a try!
No self-respecting baked potato would consider its raiment complete without freshly snipped chives. Chives can elevate even the simplest dish, and they look lovely, growing on a window sill.
Chives are members of the onion family. Chives (Allium schoenoprasum) are edible perennial bulbs. Their tender green spikes are frequently offset by purple spherical blooms that are equally edible. Many beneficial insects are attracted to the flowers, as well. Plant them once and they will provide many years of flavorful beauty.
How to grow chives
Chives are so easy to grow that they are an excellent children’s activity. Chives prefer well-drained soil with a pH of 6.0-7.0 and full sun. I have had chive plants perform equally well in partially shaded clay. This herb is tenacious - I’ve even had chive plants return after being decimated by chickens! Plant seeds 1/4 inch deep and water well. Light is not needed, at first, but seeds must be kept moist and at a temperature of 60-70°F to germinate. Chives make excellent container plants and they transplant easily, once seedlings are 4 to 6 inches tall. Established plants can and should be divided periodically to avoid overcrowding. To divide a chive plant, gently dig the entire plant out of the ground and pull it apart into smaller clumps, or you can leave it in the ground and sink a shovel down through the middle, removing a portion to be transplanted elsewhere. You will want at least 5 - 10 bulbs in the clump to be moved. Once established, your chive plants will readily self-seed.
Chive pests and diseases
The only pest I have seen on my chives is an infrequent visit from individual slugs. Onion maggots and thrips are said to cause problems, but I have never seen them. Damping off disease, powdery mildew, and pink root are also said to attack chives, but not in my experience. I think, in this case, the chive plant is the anti-pest. In fact, European gypsies traditionally hang bunches of dried chives to ward of evil and illness!
Snip off however much you will be using, as close to the base as you can without damaging the rest of the plant. If your chive plant starts looking worn out, especially in late winter, you can cut the entire plant to a height of 2 or 3 inches to stimulate fresh growth. If you harvest more chives than you need, you can snip them into small bits, lay them between layers of cloth or paper towel to dry and then store in an airtight container.
Herbs are excellent additions to an edible landscape or a windowsill garden, and chives are the easiest of the edible herbs to grow. Get yours started today!
Buds burst forth every spring, but how much do you really know about these tiny nubs?
Most buds begin forming at the end of a growing season. Generally, trees and shrubs have buds that are covered with protective scales, while most annuals and herbaceous perennials have unprotected “naked” buds. This makes sense because perennial plants need to protect their buds from cold winter temperatures during their dormant phase, while annuals do not. Many buds do require a period of cooler temperatures to stimulate their final growth phase. Unfortunately, unseasonably warm temperatures in winter or early spring can trick plants into producing hormones, called auxins, that stimulate budbreak. Opening too soon increases the chance of frost damage.
Buds are also classified by the way they grow, or their morphology. Buds can be scaly, covered, hairy, or naked.
Take a closer look at your plants today - can you tell if the buds will become leaves or flowers?
Bud pests and diseases
Being tender new growth, buds are susceptible to a large number of pests and diseases. These pests include budworms, cutworms, Eriophyid mites, citrus bud mites, weevils, thrips, and dryberry mites. Shot hole disease can also attack buds. Dormant sprays, Bordeaux mixtures, and fixed copper treatments can protect buds from many of these pests and diseases, when applied correctly. Sticky barriers can also be used to block crawling pests from ever reaching your buds.
You can grow a surprising amount of food in your own yard. Ask me how!
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