Turnips are a white, cool weather root crop.
Cousin to rutabaga, radishes, and other members of the cabbage family, turnips (Brassica rapa) are grown for the bulbous taproot that looks more like a beet, except that it is white, and its nutrient rich leaves.
Fun turnip trivia: the pink, purple, red, or greenish color of a turnip’s shoulders is a result of being exposed to the sun.
Taste for turnips
Many people believe that they do not like turnips, but this is often because the turnips they tried were too old. Old turnips taste bitter. This is because of a self-defense chemical produced by many members of the cabbage family. Also, some individuals have inherited a pair of genes that make them extra sensitive to the bitterness, so don’t force anyone to try the fruits of these labors. It just might not be possible for them to enjoy the flavor. That being said, young, tender turnips do not contain as much of the bitterness, so harvest early and often! Also, consistent irrigation reduces the chance of your turnips becoming bitter.
Turnip leaves are a popular side dish in the southeast. Tender leaves are less bitter than older leaves. Bitterness can be reduced by pouring off the cooking water and replacing it with fresh water and reheating. Unlike rutabagas, which have a visible crown or neck between the taproot and the leaves, turnip leaves grow directly from the root.
How to grow turnips
Like other root crops, turnips prefer loose soil, but they are resilient plants. They can handle conditions that thwart more gentle crops. Here in the Bay Area, turnips can be planted February through April, and again in September and October. Seeds should be planted 1/2 inch deep, directly into the garden. Seedlings should be thinned to 4 to 6 inches apart, when grown for roots, and 2 to 3 inches apart for greens. Depending on the variety planted, your turnip crop should be ready within 50 to 75 days. Tokyo turnips, which tend to be smaller, are harvestable after only 30 to 60 days!
The life of a turnip
Turnips are biennial plants, which means it takes them two years to from seed to seed. Most turnips grown in fields and gardens never get that chance. Planted in full sun or partial shade, first-year turnips put out roots and absorb as many nutrients as they can, storing them for the upcoming winter months. In the spring of a turnip’s second year, it puts out tall yellow flowers with seeds in pods that look like tiny pea pods.
Turnip pests and diseases
As a Brassica, turnips are subject to attack by caterpillars, whiteflies, cabbage loopers, Bagrada bugs, beet armyworms, and aphids. Aphids can also carry turnip mosaic, a viral disease common to Brassicas. Row covers can prevent damage, but only if they are installed before the problem starts.
Turnips have been grown for over 4,000 years. Pliny the Elder ranked turnips third only to cereals and beans as the most important crops. Turnips were also used in early experimentation with crop rotation.
Give turnips a try in your garden today!
If you grow corn, sorghum, millet, or sunflowers, you will end up with a bunch of dead, leafy stalks standing in your garden. That collection is called stover.
The word stover evolved out of the legal term ‘estovers’ from English history. An estover was the ration of wood and other resources that peasants were allotted from the King’s forests each year. It was a woodsy version of gleaning the fields. Gleaning refers to the practice of allowing peasants and strangers to collect whatever was leftover from a field after the harvest was completed.
Just as straw is left behind after a crop of oats, alfalfa, or wheat is harvested, stover was traditionally left in the field for cattle or other grazers. Some modern mushroom farmers use stover as compost for mushrooms. Dairy farmers often use stover to create silage. Silage is plant material that is cut and crushed and then stored in a relatively airtight silo without being dried ahead of time. This fodder ferments, making more easily digestible. But, I’ll bet that you do not have a silo in your backyard, or cattle to feed. So, what can you do with your stover at the end of the growing season?
The first and easiest use of stover is to add it to the compost pile. Stover often consists of half of your crop. That’s a lot of plant material. Held within that material are nutrients that other plants can use, but only if the stover has broken down. You can compost stover by cutting the heavy stalks into one-inch pieces and keeping it near the bottom of your compost pile. For shorter crops, such as millet and sorghum, I simply cut the plants off at ground level and toss it all to my hens, who make short work of the greens. [The sorghum comes back each year for a continuous supply of greens and seeds for my hens and I always manage to miss some of the millet seeds, so they pop back up each spring, as well.]
In commercial agriculture, stubble cultivation refers to the act of plowing all that stover back into the earth. This returned the nutrients back into the soil and improves soil structure (assuming the heavy farming equipment doesn’t compact the soil too much). In my mind, stubble cultivation is a twist on the Three Sisters Method of planting. Rather than cutting down tall stalks of corn or sunflower, these sturdy poles can be put to work. Simply plant cool weather climbing plants, such as peas, at the base of each stalk. The petioles (tiny stems that attach leaves to bigger stems) make perfect handholds for tiny tendrils. The peas grow up and up and up and you don’t need to install or maintain a trellis! After your pea crop is harvested, you can cut the stalks off at ground level, chop them into bits, and add them to the compost pile. Or, you can use them again, as bean poles!
Other uses for stover
There are other creative ways to repurpose those tall, study stalks before they need to be composted. Here are some of my favorites:
How do you put your corn and sunflower stover to use? Let us know in the Comments!
Parsnips look like white carrots, well, because they are related!
Cousin to carrots, parsley, celery, and other umbels, parsnips (Pastinaca sativa) are native to Eurasia and have been cultivated since ancient times. In fact, parsnips were used as a sweetener before sugar cane made its way to Europe!
Parsnips are a cool weather crop in the Bay Area and other Mediterranean climates. Parsnips can be planted in September, and then again in February, March, and April in our region. If you live in a different area, simply check with your local Cooperative Extension Office for your best planting times.
Parsnip plant description
Parsnips leaves look almost like ferns, with pinnate (branched), toothed edges (margins). Parsnips are grown as annuals, but if you let a few of them go to seed, these biennials can start spreading edible roots in many areas of your foodscape. [Once they start that process, you won’t want to eat them - they get quite woody.] Second year plants can grow 5 feet tall, but your first year parsnip will be significantly shorter, at only 18 to 24 inches. Yellow, umbrella-shaped flowers grow into tiny ‘fruits’ called schizocarps. [How’s that for a fun garden word?]
How to grow parsnips
Parsnips, like other root crops, need loose soil. This makes them well suited to raised beds and container gardening. If you are planting parsnips in the Bay Area’s heavy clay soil, you will want to break up the soil down 18 inches and dig in 3 or 4 inches of aged compost. If you don’t, you will end up with forked and otherwise deformed roots prone to disease. Parsnip seeds should be planted 1/2 inch deep, with a heavy dose of patience. Parsnips seeds are slow to germinate and the plants take up to 4 months to reach harvestable size, but they are worth the wait! These sweet roots lend themselves to seasonings such as ginger and nutmeg, as well as more savory dishes, such as soups and stews. Parsnips can be grown in full sun or partial shade. They prefer slightly acidic soil, so you may need to make some pH adjustments. Seedlings should be thinned to stand 3 to 6 inches apart and be sure to eliminate all competition from weeds.
Parsnips pests and diseases
I had a difficult time tracking down parsnip pests and diseases in the Bay Area. Other regions had plenty to say, but my guess is that the Bay Area is not conducive to growing parsnips commercially, so it gets less attention. Being more than a little determined, I am going to try growing them anyway!
It is my guess that, being a close cousin to carrots and parsley, parsnips will probably have many similar problems. These include armyworms, cabbage loopers, and aphids. Fusarium wilt, powdery mildew, bacterial leaf spot, and alternaria leaf blight may also occur. Other regions mention how celery fly larvae may tunnel into parsnip leaves, much like leaf miners. These pests can harm young plants, so remove infested leaves if you see them. I also found plenty of warnings about carrot flies. Carrot fly larvae are likely to attack parsnip roots, providing points of entry for canker and other fungal diseases. These pests are attracted to the smell of bruised plant tissue, so be gentle to your parsnips!
According to Wikipedia, parsnip canker is a real problem when growing this crop. Parsnip canker shows itself as orange-brown or black areas on the crown and shoulders. Also, the roots will crack. This condition is more likely to occur when seeds are planted in cold, wet ground that is too alkaline. It sounds, to me, that poor drainage is a parsnip’s worst enemy.
On the upside, many moth and butterfly larval forms use the flowers and undeveloped seeds of second year parsnips as a major food source. So, allowing a few parsnip plants to complete their lifecycle not only gives you free parsnip seeds and plants, it also adds biodiversity to your landscape and provides food for many beneficial insects!
Like many other root crops, parsnips taste sweeter after they’ve experienced a little frost. Since our ground is not likely to freeze, we don’t need to worry about getting our parsnip harvest out of the ground before it does. Other regions are not so lucky. Before you harvest your parsnips, however, be sure to wear gloves. Parsnips may be good sources of folic acid, potassium, fiber, and vitamins C and K, but they also have a powerful self-defense mechanism. Parsnip sap is toxic. If your skin is exposed to sunlight after handling parsnip leaves and stems, you are likely to get a rash. So, wear gloves.
Give these sweet root crops a try this winter and let us know what you think!
Persian limes with brown bottoms have stylar end rot.
Also known as stylar end breakdown, stylar end rot generally affects Bearss, Tahitian, and other Persian limes species, though it has been seen in other lime and lemon varieties. Stylar end rot is a physiological disease, which means it is not caused by pests or pathogens. Instead, stylar end rot is caused by too much heat and drought. Even though limes, lemons, and other citrus have thick, waxy skins to protect themselves from the sun’s heat and drought conditions, sometimes that protection isn’t enough.
Symptoms of stylar end rot
The stylar end of a fruit is the part with the dried up flower petals, opposite the stem end. Stylar end rot starts out as a small, grayish sunken area, at the stylar end, that slowly becomes firm and leathery. Affected areas can spread to cover 1/4 to 1/2 of the fruit, which is often invaded by bacteria or fungi. The tissues inside break down and turn brown or pink. Diseased fruit can be added to the compost pile, but only if it is free of other fungi and bacteria. Otherwise, toss it in the trash. Stylar end rot found on guava has been found to be caused by a fungi, Phomopsis. Some fungal diseases exhibit similar symptoms:
Mealybug destroyers, also known as mealybug ladybirds, are close cousins to our beloved lady beetle, or lady bug. In fact, many members of the Coccinellidae (kox-ih-NELL-a-DEE) family are beneficial predators, but not all. With a name like mealybug destroyers, you know that your garden plants are going to love this tiny beastie!
Mealybug destroyers (Cryptolaemus montrouzier) are native to Australia. They were brought to the U.S. in 1891 to combat California’s citrus mealybugs. Most mealybug destroyers cannot handle cold temperatures, but some populations have remained along coastal areas.
Mealybug destroyer identification
Like their close cousin, the lady bug, mealybug destroyer adults have the same dome-shaped body and short, stubby antennae. [That's a pretty cute little face, too, wouldn't you agree?] Mealybug destroyers, however, have black wing cases (elytra), with orangish-brown shoulders and rear end. Adults are only 1/6 of an inch log, so you may never notice them. If you decide to take a closer look with a hand lens, you might be able to see that females have dark brown forelegs and males’ forelegs are light brown. The larval forms, which can reach 1/2 inch in length, are often mistaken for wooly aphids or mealybugs, because of their elongated, alligator shape and waxy, white filament covering. Yellow eggs are laid near mealybug eggs for easy access to their favorite food supply.
Mealybug destroyer diet
A single mealybug destroyer may eat 250 mealybugs in its short lifetime. They also feed on soft scale insects. And it is not just the adults who hunt down and kill our garden enemies. While adults chomp and chew, larval forms pierce and suck the life juices from many sap-sucking garden pests.
So, why would a gardener care about mealybugs? Cousin to aphids and whiteflies, mealybugs are sap eaters. They feed on new buds, shoots, and leaves, causing erratic or reduced budbreak, slowed growth, and twig dieback. Mealybugs are frequent pests to basil, grapes, stone pine, pomegranate, chamomile, apple, plum, pear, peach, ferns, orchids, and, well, quite honestly, pretty much everything growing inside or outside of your home. Mealybugs produce honeydew, which provides the perfect growth medium for sooty mold. They can also carry bean mosaic. That’s why.
Attracting mealybug destroyers
It is highly unlikely that there are any mealybug destroyers in your neighborhood to attract. They simply cannot handle winter weather. So, you will probably have to buy mealybug destroyers each spring. What you can do, to prevent them from flying away as soon as they arrive, is to provide biodiversity. This means installing a wide variety of plants, with various heights, shapes, and colors. And avoid those broad spectrum insecticides.
Mealybug destroyers may not occur naturally in the Bay Area, but they sure can help maintain the balance of power in your foodscape!
Flea beetles hop from plant to plant, chewing tiny holes in leaves as they go.
We are not talking about the blood-sucking, disease-carrying fleas on squirrels. Instead, flea beetles are plant pests. Generally, they do not cause a lot of damage. After all, each flea beetle is only 1/16 to 1/8 of an inch long! If your plants are hosting enough of them, however, the damage can slow growth or provide points of entry for bigger problems. Let’s see what your plants are up against.
Flea beetle varieties
There are dozens of leaf beetle species. Here in the Bay Area, you are more likely to see these particular pests:
Flea beetle host plants
Flea beetles feed on many families of edible garden plants:
Also, carrots, corn, and sweet potatoes may find themselves on the menu. Flea beetles are also attracted to yarrow, but this is a good thing. Yarrow acts as an insectary. Beneficial insects have evolved to lay their eggs in plants such as yarrow, knowing that flea beetles and other pests will provide their young with an easy first meal. Other beneficials, such as big-eyed bugs, will also feed on flea beetles, so go easy on the pesticides. Pesticides don’t work very well on flea beetles anyway - they simply hop away.
Flea beetle damage
Pitting and small, irregular holes in leaves may merge to create raggedy areas. The holes are smaller than the damage caused by shot hole disease. Shot hole disease holes usually begin as 1/10 to 1/4 inch diameter red or purplish spots. There may be a pale green or yellow ring around each spot. As the dead tissue dries up and falls away, the shotgun blast look will appear. Small, irregular leaf holes may be caused by springtails, but it is more likely to be flea beetles. Fruits and roots may also be damaged by flea beetles.
Flea beetle lifecycle
Flea beetles lay tiny eggs in weeds, plant debris, and in the soil surrounding their favorite food plants. After the eggs hatch into thin, white larva, feeding may begin above or below ground. After a month or so, the larva pupate in the soil. When they emerge as adults, they use their big jumping legs to go wherever they want to feed.
Flea beetle control
Since pesticides are not very effective on flea beetles, other controls must be used, if control is actually needed. In most cases, it isn’t. If an infestation starts to cause serious damage, use basic sanitation in the garden. Removing all those tiny hiding places can make life difficult for flea beetles. Reflective mulch and white sticky traps can also be used, and row covers may block pests from reaching plants in the first place. Once they are present, you can lightly sprinkle the area with diatomaceous earth (DE). Apparently, flea beetles don’t care too much for sulfur, either.
Some commercial growers actually vacuum off heavy flea beetle infestations, but I don’t recommend it for the home gardener. You vacuum cleaner would never be the same!
Chinese cabbage refers to two different cool weather crops that lend themselves to Bay Area fall and winter gardens.
Chinese cabbages (Brassica rapa) are variations on the lowly turnip. The two subspecies we most commonly see are forms of Napa cabbage (var. pekinesis) and bok choy (var. chinensis). These healthful foods have been grown in China since before the 15th century.
Also known as Korean small cabbage or celery cabbage, Napa cabbage has a milder flavor than more domestic varieties, but it packs a nutritional punch that’s difficult to beat. According to a study conducted by the Centers for Disease Control in 2014, Chinese cabbage ranks second only to watercress as a nutrient dense food. Napa cabbages come in both head and loose leaf varieties. Napa cabbages can be planted in the Bay Area twice each year: first, February through April; and again, August through October.
Unlike the Napa cabbages, bok choy does not form heads. Bright white stalks give way to dark green blades, growing in a cluster, much like celery. Bok choy can be planted in the Bay Area in September and October, and then again, February through April.
How to grow Chinese cabbages
These biennial plants are generally grown as annuals. If you allow your plants to go to seed, you can create a seasonally perpetual crop within your landscape. To begin, find a location with full or partial sun and well-drained soil. Adding aged compost to the planting bed ahead of time can provide a nutritional boost to your plants and improve soil quality, while you’re at it. Chinese cabbages can also be grown in containers. Use pots that are 8 to 12 inches across and 18 to 24 inches deep. Seeds should be planted 1/2 inch deep and successful seedlings should be thinned to 12 - 18 inches apart. These plants do not transplant well, so it is better to put them where you want them right from the beginning.
Pests and diseases
Being closely related to broccoli and cauliflower, Chinese cabbage is subject to many of the the same pests: aphids, flea beetles, armyworms, loopers, cabbageworms, leaf miners, and millipedes. Common diseases include white rust, damping-off, yellow virus, clubroot, black rot, and bottom rot. Many of these diseases can be prevented by allowing soil to dry out between waterings.
Harvesting Chinese cabbages
Chinese cabbages are good candidates for succession planting. If you start one new plant per person every two weeks, through fall and winter, you will have an abundance to harvest. You can extend that harvest by only cutting away outer leaves on an as-you-need-them basis. These plants will continue to produce inner leaves through the growing season.
Like other cabbages, these plants to not produce a lot of ethylene gas. Ethylene gas is what makes fruits and vegetables ripen. Cabbages are, however, very sensitive to the ethylene gas produced by other plants, so it is a good idea to keep harvested leaves or heads in a plastic bag in the refrigerator. Or, your can always try your hand at fermenting some cabbage for your very own kimchi!
Idioblasts are specialized plants cells that are very different from the cells around them.
Most plant cells are grouped together with other, similar cells: leaf cells with leaf cells, root cells with root cells, and so on. Hidden within these normal groupings are cells called idioblasts.
Scientists believe that idioblasts are the precursors to many specialized cells, such as stomata, glands, and guard cells. When idioblast cells divide, they often create daughter cells different from themselves. These mutations have given rise to much of the diversity within the plant world. At the same time, many idioblasts have remained the same over time, providing important functions within a plant. According to Albert Paul Kausch, in his 1985 doctoral thesis, The development, physiology, and function of selected plant calcium oxalate crystal idioblasts, no one really knows how or why idioblasts form.
Most commonly, idioblasts are storage cells. But some idioblasts hold a defensive arsenal of poisons and pointy crystals!
When botanists and scientists talk about idioblasts, they divide them into several groups, depending on function.
Some idioblasts are simply storage cells. They may store pigment, food, waste products, water, resin, latex, oil, or tiny stones of silica (phytolith). Until recently, it was not understood why plants contained silica. Then, some scientists tried growing plants in soil without any silica. Many of these plants flopped over. Mystery solved. Sort of. Then, another group of scientists, led by Fergus P. Massey, proposed that plants evolved to contain silica for more than just structural support. They claim that plants absorb these minerals as a defense mechanism. Massey and his team point out that silica in plants tends to wear down the teeth of those who eat them. There is debate about the truth behind this assumption. You decide.
Idioblasts as manufacturing centers
Other idioblasts do more than just store materials. Some idioblasts actually manufacture important compounds. For example, avocado skins have idioblasts with antifungal properties. Other idioblasts produce mucilage carbohydrates (mucus cells) that store water. Other idioblasts, called phenolic cells produce and store carbolic acid to be used as defensive weapons.
Idioblasts as weapons
While we consider herbivores to be mostly harmless, plants do not share that view. Rooted to one location, and without claws or fangs, plants have to get creative when it comes to defending themselves against grazers and other plant eaters. This is where idioblasts get really interesting. Some idioblasts contain biforine cells. Biforine means having two doors. [Isn’t that a great word?] These cells are oval-shaped with openings at each end. When something (or someone) bites the plant, breaking the cell, crystals of calcium oxalate shoot out, poisoning or irritating the attacker! These oxalates are produced in the vacuoles of the idioblasts. Oxalates are toxic to the plant, too, but the plant protects itself by binding the material up in crystals. These crystals come in many shapes. They may look like a grain of sand, a pencil (styloid), a needle (raphide), or prismatic (isodiametric). Bundles of raphides or prismatics are called a druse.
Plants that use these weapons
Many plant families rely on druses stored in idioblasts for protection. These families include:
Botanists believe that plants also use these calcium oxalate-filled idioblasts to provide structure to the plant, and as a way to store calcium.
This information may not help your grow brighter flowers or more delicious tomatoes, but your mind needs to grow, too! And who can resist a word like idioblast?
One or two minutes may be all the warning you get when it comes to fire.
In light of all the fires raging in Northern California, I am dedicating today’s post to fire safety and how it pertains to the plants around your home.
Several years of drought have killed hundreds of millions mature trees across the country. In California, over 102 million trees have died since 2010, and 62 million trees died in 2016 alone! Many of the remaining trees are not as healthy as they could be, due to bark beetle infestation and disease. These trees have more dead leaves and dry twigs, making them susceptible to fire.
Fire in landscapes
You learned it back in elementary school: fire needs fuel, heat and oxygen to keep going. A single spark can land on dry grass, move to a shrub, climb a tree, and then leap to your home, taking everything you own with it. It can also take your life. Gardening for fire safety means interrupting that spread. Rather than allowing fire to move through your landscape using shrubs and trees as a super highway, you can create spaces that slow or stop the flames.
California state law (Public Resources Code 4291) requires that all rural homes have a 100-foot defensible space. Suburban homes face different challenges, but fire safety is still critical and many of the suggestions still apply. Each county has its own set of ordinances, so be sure to check with local authorities. Even without the law, fire safety around your home just makes good sense.
Defensible space can slow or stop the spread of fire. It also helps keep you, your family, and our heroic firefighters safe. Your defensible space is made up of two zones.
Zone 1 - According to CalFire, the first zone consists of a 30-foot perimeter around any buildings, sheds, or decks on your property. Maintaining this zone means:
Zone 2 - The second zone extends 100 feet from your home. To maintain Zone 2:
Spacing plants and trees
By creating space between trees and shrubs, the spread of fire can be slowed or stopped. The spaces are both vertical (up and down) and horizontal (side to side). To maintain safe vertical space, remove any tree branches that are 6 feet from the ground or less. In areas prone to wildfire, bushes growing near tree canopies need three times their height before the lowest tree branches to prevent fire from spreading. This means that a 4 foot tall shrub would need 12 feet before the closest tree’s lowest branch to be fire safe.
Horizontal spacing is a function of slope. Areas that are flat or with slopes less than 20% can allow trees to be 10 feet apart. Shrubs should be two times their height apart. This means 4-foot shrubs should be 8 feet apart to be safe. Slopes of 20 to 40% require shrubs to be 4 times their height apart and trees need 20 foot spacing. To keep slopes greater than 40% fire safe, trees should be 30 feet apart and shrubs need to be 6 times their height apart. These rules apply to rural properties, but you can apply them to your suburban home, as well.
What about all that mulch?
Nearly everything you read in The Daily Garden reminds you of the benefits provided by mulch: moisture retention, weed reduction, temperature stability, reduced soil compaction, and so on. But what about flammability? Does all that ground cover create a path for fire? Luckily for us, a group of fire and gardening professionals got together in Nevada to test various types of mulch. This is what they learned about each type, listed in order of worst to safest, all used at a depth of 2- to 3-inches, unless stated otherwise:
Use fire-resistant plants
We all know that green plants burn a lot more slowly than dead, dry plants. And there are no truly fire-resistant plants. If it gets hot enough, anything can burn. You can help keep your home safe by planting low-growing, high-moisture plants closest to your home. Succulents certainly come to mind. When deciding where to install plants, imagine your home in the bottom of a shallow bowl. The height of your plants should get taller as your move away from the building. This would help draw fire away from your home, rather than towards it. The following plants are less likely to be a fire hazard:
The added advantage to many of these plants is that they have evolved to withstand drought, which means many of them require less water. UCANR provides a list of low-risk, Fire-safER plants. Despite their name, evergreens, such as pine and fir, are far more flammable than the hardwoods.
Create a fire safety plan. If you live in rural areas, use the Wildfire Safety Plan. If you live in a city or suburban area, use the plan provided by the National Fire Protection Association. Seriously, people. It takes 20 minutes and could save your life.
To learn more about how likely fires are in your area, check out the maps provided by the National Park Service. Also, CalFire offers a homeowner’s fire safety checklist that deserves your attention.
In case of high fire risk
If fire risk is especially high, you may want to take the following actions before it is too late:
Bottom line: keep your plants green and healthy and move flammables away from your home.
Above all else, in case of fire: GET OUT AND STAY OUT. Everything else is temporary.
Autumn colors are caused by senescence.
Senescence is the life stage of a plant or plant part when its metabolism slows prior to dying.
Our lovely fall colors are caused by a deciduous tree’s inability to maintain chlorophyll levels within its leaves. Chlorophyll, being green and abundant most of the time, masks the other colors that are alway present within a leaf. Shorter days and cooler temperatures trigger the tree to form a layer of cork at the base of each leaf, blocking the flow of water and nutrients and interfering with the leaf’s ability to produce chlorophyll. Eventually, the other colors can shine through. The veins of a leaf are the last part to turn color because it is the last place nutrients were available.
Autumn leaf color and the final days of a flower’s life are examples of developmental senescence. Developmental senescence occurs at the cellular level in all life stages. The seed leaves of a bean plant experience senescence when they wither and fall off. The mature leaves of the same plant will also exhibit senescence when they die. Ultimately, the metabolism of the entire plant will slow to the point of death. In each case, developmental senescence is triggered from within the plant.
Sometimes senescence is not developmental. It can also be induced for laboratory research, or as a result of injury or stress. Water stress can trigger senescence. A large plant with many leaves may be unable to maintain its canopy in a drought. Rather than risk death, it absorbs water and nutrients from outer leaves and then seals them off from the food supply, allowing them to fall away. Sunburn can also cause senescence. As an under-hydrated leaf receives direct sunlight, the cells most damaged slow their metabolism and relinquish their water and nutrients to the surrounding cells.
As seasons change and plants age, you will see many examples of senescence, but the colors of autumn are my favorite!
The Calvin cycle describes what happens to light energy after it has been absorbed into a leaf.
Put on your steampunk magnifying glasses because, today, we are going deep into the molecular level of leaves to learn how they make energy from sunlight.
Also known as the Calvin-Benson cycle, Melvin Calvin won a Nobel Prize in Chemistry for figuring this out. That was in 1961. Until Melvin’s research was complete, everyone thought that photosynthesis consisted of chlorophyll interacting directly with carbon dioxide to create edible organics (sugars) for plants. Instead, his research taught us that light energy causes chlorophyll to trigger plants to produce those organic compounds for themselves!
So, how does photosynthesis work?
Photosynthesis occurs in two steps. The first step is the light dependent reaction. This is when the sunlight is absorbed and transformed. To do this, electrons are torn from water molecules, creating oxygen as a waste product. When this happens, hydrogen (H) is released and used to create two compounds: nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP). The second stage of photosynthesis is the light independent reaction, or the Calvin cycle. This is when the ATP is converted into glucose.
Each stage of the Calvin cycle has its own enzyme. Enzymes are chemical catalysts that trigger change. After light energy has entered a plant through the stoma and been converted into ATP and NADPH, the light-independent (or ‘dark’) aspect of photosynthesis can begin. There are four stages to the Calvin cycle:
For your chemistry buffs, here's the equation and a graphic:
In the illustration above, atoms are represented as black (carbon), white (hydrogen) red (oxygen) and pink (phosphorus).
For the rest of us, try this story for a more memorable form:
Rubio marries Connie. Connie has twins. One twin becomes a cook. The other twin works family business and marries a girl just like mom. And they have twins. And so it goes….
Factors that interrupt the Calvin cycle
Any interruption in photosynthesis leads to chlorosis, or yellowing. Chlorosis can be the result of insufficient light (epinasty), disease, a lack of mycorrhizae, or sunburn. Other factors that interrupt the Calvin cycle include:
If you see chlorosis, it means your plant is starving. By learning about the Calvin cycle, you may be better equipped to figure out what is wrong with your plants. Get growing!
* RuBisCO - ribulose bisphosphate carboxylase/oxygenase; believed to be the most abundant enzyme on Earth (Wikipedia)
Phoresy describes the relationship between two organisms in which one is a hitchhiker, but not a parasite.
The fleas that catch a ride on your dog or cat are parasites. They catch rides and then drink the blood of our beloved pets. This is not phoresy. Now, picture a person riding a horse. Person plus horse equals phoresy. The person is being transported by the horse, but is not a parasite.
In many cases, electron microscopy is needed to actually see phoresy in action. And many phoretic insects lose the ability to catch a ride once they have reached a destination. Like many other insects, those that use phoresy may go through several very different life stages, such as phoretic, parasitic, and reproductive stages.
In nature, phoresy can bring both pests and beneficials to your garden. Here are just a few of the situations in which phoresy occurs.
We may love to see hummingbirds flitting through the garden, but you should be aware that hummingbirds may carry flower mites. Flower mites are tiny, nectar stealing pests that run up a hummingbird’s beak as it feeds. Grabbing ahold of the hummingbird’s nostrils, flower mites then go for a wild ride in hopes of reaching a new food source. When the hummingbird stops to feed at a different flower, the mite runs down the hummingbird’s beak to gorge on as much nectar as it can before hopping another ride to yet another flower.
Moving in the opposite direction, it has recently been discovered that varroa mites, the bane of honey bees, are phoretic. These devastating parasites of the honey industry lie in wait for unsuspecting honey bees to visit a flower. As the bee collects nectar and pollen, varroa mites catch a ride that ultimately takes them to the hive. These parasites suck the life fluids from developing and adult bees. These pests also carry viruses that infect honey bees. Varroa mite infestations can kill an entire hive, if left untreated. Varroa mites are just one aspect of the global problem of colony collapse disorder.
Male ground bees are seduced by blister beetle larvae into carrying them to female ground beetles, phoresy style. Blister beetle larvae emit a pheromone that is similar to the perfume used by female blister beetles to attract males. When male ground bees approach, the blister beetle larvae attach themselves to the male bees. After recovering from their disappointment, the male bees continue their search for a female. When she is found, the male bee blindly does his business as the blister beetle larva moves to the female bee. When she returns to her nesting area, the larva jumps off and begins feeding on everything it can - nest, provisions, and eggs.
Pseudoscorpions are tiny beneficial insects that feed on ants, thrips, small flies, springtails, carpet beetles, clothes moth larvae, booklice, and spider mites. They also get around using phoresy by catching rides on many different flying and crawling insects. In some cases, they even provide a service to the carrier insect by eating its parasites along the way!
One phoretic wasp, Trichogramma, catches rides on mated female imported cabbage moths to reach areas where eggs have been laid. These beneficial wasps then parasitize the eggs, making our jobs as gardeners so much easier. Research on this behavior is new, but very exciting!
Greenhouses provide the warmth, sunlight, and moisture that plants need to thrive. The same is true for thrips, whiteflies, leafhoppers, and fungus gnats, just to name a few. While reputable greenhouse growers do their best to eliminate pest phoresy on the plants they sell, it still happens. Many imported pests and diseases are brought into new areas through phoresy. When you bring plants home, you also risk bringing phoretic pests and diseases. This is why it is so important to create a quarantine area. Forty days and nights goes a long way toward sorting out and preventing more serious problems.
So, quit "phoresing" around! Go take a closer look at your plants and the insects that call them home. You may be surprised to see what’s out there!
Succession planting takes a long term view of garden usage. Instead of simply planting whatever seed packets looked best in the garden catalog, successful gardeners look at the same space over time to see what can be planted after the current crop.
Benefits of succession planting
Succession planting makes efficient use of fertile ground by leap-frogging plants and crops for a continuous harvest. This eliminates the deluge of every plant reaching harvestable size within the same week. That’s great if you’re putting up tomato sauce, but it can be a bit much when talking about 20 Romaine plants! By changing the life stage and/or plant type in any given bed, the odds of total crop failure due to pests or disease are reduced. Growing plants at various life stages in the same place also cuts back on the amount of real estate available to weeds. Finally, planting fast-growing crops with slow-growing crops makes good use of soil that might have otherwise gone fallow.
Different methods of succession planting
In its simplest form, succession planting refers to following one crop with another crop. This is generally done as the weather changes, following a summer crop with a cool season crop. But there is more to it than that. In addition to consecutive plantings, there is also staggered planting, intercropping, and varietal planting.
Varietal planting means installing different varieties of the same plant in the same place, at the same time. These varieties have different maturity dates, providing a continuous harvest. You can fine tune your varietal plantings by taking note of days to maturity and mature size information on seed packets. You may be able to start with an early maturing variety, followed by a mid-season harvest, then a late-season harvest. You may even be able to squeeze in yet another early harvest at the end.
Staggered planting refers to planting seeds of the same plant in the same area, but on different days. This extends the harvest season, providing a continuous, smaller harvest of the same plant. Staggered planting is best suited for lettuce, spinach, radishes, beets, carrots, and peas. For most of these crops, you can start a new set of seeds every week or two, for the best possible production.
Intercropping puts different crops together in the same place, at the same time. This allows gardeners to make use of soil resources that might have gone unused with a single crop. It also increases biodiversity, reducing potential pest and disease problems. One example of intercropping is the Three Sisters Method of growing beans, corn and squash together. Intercropping is the scientific basis behind the Companion Planting craze. I’m sorry, but there are no magic pairings of plants that “like” each other. There are structural and developmental needs of different plants that either support one another or don’t interfere with each other, while growing in the same space. Basic intercropping pairings include:
Planning for succession planting
Your can take advantage of the benefits of succession planting, simply by growing two seasonally different crops in the same bed. As one crop is winding down, the next season’s crop can be getting started. Or, you can get really in-depth into this concept by investing some planning time. To make the most out of your garden space with succession planting, you will need to know the following:
Here in the Bay Area, our growing season is nearly year round. So the next step will be to collect information on all the plants you want to grow. You can do this with pencil and paper, in a spreadsheet, or you can clean off a big table and start moving seed packets around into different groups until you reach what looks like a good plan.
Do yourself and your garden a favor and take note of what works and what doesn’t. Just remember, every garden is different, every year is different, and sometimes we are simply unlucky when it comes to temperature extremes, pest infestations, and nutrient deficiencies. Succession planting can offset some of those problems.
Clubroot is not the newest bar in town; it is a disease of many fall and winter crops.
Clubroot, or club root, is caused by an imported plant parasite that grows inside of plant cells. This parasite used to be classified as a slime mold, but is now in an entirely different category, called Phytomyxea. This pathogen is called Plasmodiophora brassicae, but don’t let the name scare you off from learning about it. The brassicae part of the name tells you which plants are susceptible: members of the cabbage family. The Plasmodiophora part of the name tells us that these are mouthless, amoeba-like plant parasites.
Which plants are affected by clubroot?
Clubroot occurs in nearly all members of the brassica family. This means that your broccoli, Brussels sprouts, cabbages, cauliflower, radishes, and turnips are susceptible. In addition, alyssum, mustard, nasturtium, and wallflowers, as brassicas, can also become infested with this parasite.
Symptoms of clubroot
At first, there may not be any aboveground symptoms to clue you in to this problem. Leaves may begin to wilt or look stunted. They may yellow. Of course, those symptoms could be any number of issues: water stress, nematodes, thrips, aphids…it’s a long list But, if you were to dig the plant up and look at its roots, well, that would be a different story altogether. Roots infested with clubroot parasites are covered with galls (ulcerations). They are also distorted and swollen, interfering with the transfer of water and nutrients that keep the plant alive. One look at the roots and you will know that something isn’t right.
Once this micro-critter is in your soil, it may never go away completely. Soil solarization is the only sure way to get rid of it, and that only works if the solarization is done properly. Use these tips to reduce the chance of clubroot occurring in your garden:
When it comes to clubroot, prevention is worth the effort.
Correct overcrowded roots with division. Not the chalkboard variety, but by digging plants up, cutting them apart, and replanting.
Do my plants need dividing?
If production is down among your perennial plants, it may be that the roots have become too crowded. You can fix that with division. Division is a form of asexual propagation used on perennial plants. Annuals and biennial plants do not live long enough to make this method worthwhile. Signs that your perennials need dividing:
Why divide plants?
There are many perennial plants that benefit from dividing every few years. Plants that grow from rhizomes, such as bunch grasses, asparagus, and ginger, can be divided simply by digging up a section of the underground stem and cutting between the established plant and new growth, and planting the cut end someplace else. Many other perennial plants grow from corms and bulbs. These plants reproduce underground by creating offsets and bulbils, respectively. In either case, over time, it gets crowded down there!
Which plants need dividing?
Some plants, peonies and hostas, for example, never need dividing. Others, such as iris, Shasta daisies, and coreopsis should be divided every 2 or 3 years. Daylilies, evening primrose, and bergenia generally need dividing every 5 years or so. Many other garden plants vary in their need for division, depending on soil health, plant age, climate, and more. It’s generally a case of being observant and noticing when the following plants look like they need some breathing room:
When should plants be divided?
Autumn is generally the best time to divide plants. Autumn-blooming plants, such as saffron crocus, should be divided in spring. In both cases, temperatures are neither too hot not too cold, and plants will have time to recover before winter’s chill slows growth to a halt, or the summer sun bakes everything to a crisp.
How to divide perennial plants
Don’t be afraid to try dividing your plants. They will be far healthier and more productive once they reestablish themselves. Follow these steps to divide the perennials in your landscape:
Help your perennial plants reach their full potential by periodically dividing them. By dividing, I transformed my overcrowded, unhealthy, and unhappy Shasta daisy into 15 separate plants that now have room to grow and thrive and bloom!
Hoverflies, or syrphid flies, are one of the most beneficial insects you can attract to your garden.
Hoverflies are members of the Syrphidae family. There are over 6,000 species worldwide and 300 on the West Coast. Many of them mimic bees and wasps to discourage predators, but they are harmless to humans. Hoverflies mimic bees and wasps in other ways, too, as both predators and pollinators.
With so much variety, there is no one description that covers all hoverflies (also spelled hover flies). They can be as large as 3/4” long or so small that you won’t notice them. They can be black or colorful, spotted, striped, or plain. What they all have in common is the fact that they tend to hover over their favorite flowers. There are some bee flies that also hover, but they are equally beneficial as both pollinators and predators, so you don’t really need to know the difference* between the two species. Hoverfly larvae are blind and deaf. They are only 1/32 to 1/2 of an inch in length. They may be green, brown, yellow, or nearly transparent. They may have a white longitudinal stripe.
* If you really need to know the difference, hoverflies have shorter legs, a prominent beak, and a line along the back of their wings, while bee flies have longer legs, a sloping face, and clear wings. Also, bee flies are more likely to be hairy. There. Now you know.
Once a female has mated, she will seek out a good place to lay her white, elliptical eggs. A good place, to a hoverfly, is one that looks like there will be plenty of aphids for her young to eat. After they hatch, hoverfly larvae hang onto a leaf with their back end and swing back and forth, looking for prey. Once found, the prey are poked and sucked dry. The larvae leave a trail of empty husks to show where they have been feeding. Eventually, the larvae create a green or dark brown pupa around themselves, where they will metamorphosis into adults.
Not all hoverflies behave in the same way, but there is enough variety to safely assume these are bugs you want in your landscape and garden. Some hoverfly larvae are saprotrophs, which means they each decaying plant and animal matter in the soil. This improves soil structure and makes nutrients available to plants. Other hoverfly maggots are powerful predators, devouring a lion’s share of aphids and other plant-sucking pests.
Hoverflies as predators
Most hoverfly species larvae will eat aphids, thrips, mealybugs, mites, scale insects, and leafhoppers. That’s a good thing, because these pests spread several diseases, including curly top, powdery mildew, black spot, rust, and sooty mold, just to name a few! Other hoverfly larvae prey on caterpillars, slugs, and codling moth larvae. In my book, there are no bad hoverflies.
Hoverflies as pollinators
As adult hoverflies feed on nectar and pollen, they also pollinate many of your garden crops. In fact, hoverflies are second only to bees when it comes to pollination. Unlike bees, which tend to prefer specific species, hoverflies are generalists, landing wherever the picking looks good.
There are several insectary plants that attract hoverflies. Most of these plants provide pollen and nectar to the adult forms. Hoverflies prefer plants that have shallow or umbrella-shaped flowers. These plants are often members of the Umbelliferae or Apiceae family. Adding the following plants to your landscape is sure to attract these beneficial insects:
Research has shown that hoverflies prefer yellow and white flowers over other colors. Since organic pesticides, such as spinosad, also kill beneficial hoverflies, you may want to think twice about when you spray. Once flowers are in bloom, you may want to hold off.
Orchid trivia - One type of orchid, Epipactis veratrifolia, emits chemicals that mimic the alarm pheromones used by aphids. This attracts hoverflies, resulting in pollination. Stuff like that makes me wonder what else is going on that we never notice...
Legumes are nitrogen-fixing plants that produce many of the foods we eat.
Peas and beans are common legumes. Peanuts, chickpeas, alfalfa, clover, lentils, vetch, mesquite, carob, tamarind, lupins, wisteria, and soybeans are also legumes. The unique behavior that makes legumes so valuable is that most of them are able to convert atmospheric nitrogen into a form that is usable by other plants.
Over 80% of our atmosphere is made up of nitrogen. Plants are greedy for nitrogen, but they can’t use atmospheric nitrogen. Some plants, our beloved legumes in particular, have developed mutually beneficial relationships with certain bacteria that live on or in their roots. These bacteria are able to combine atmospheric nitrogen with hydrogen to create ammonia, which is then converted into a usable form of nitrogen. This is called the Nitrogen Cycle and is what makes legumes an important part of crop rotation and cover crops. Some people claim that marigold plants interrupt the nitrogen-fixing ability of legumes, but I have not found any research to support those claims.
With so many family members, it should come as no surprise that there is plenty of variety. Some legumes grow low to the ground in a spreading habit, while others vine, and other stand upright. All legumes are dicots, which means they produce two seed leaves before true leaves appear. It also means that the seeds tend to be made up of two halves. The fruit, nut, or seed of legumes is technically called a pulse. Pulses are grain seeds held within a pod, or simple dry fruits, that develop from a single carpel. Most legume seeds have a “zipper” along one side that opens up when the seed is ripe. This behavior is called dehiscence. These seeds are often rather large and fast-growing, making them an excellent choice when gardening with children.
Legumes as soil amendment
Legumes can be used as a green manure, cover crop, or an edible harvest. When used as a green manure, plants are allowed to reach the flowering stage and are then cut and left where they fall to decompose. This returns valuable nutrients to the soil and improves soil structure. Other legumes are grown as a cover crop to prevent erosion. Most legumes have strong, deep roots that help aerate compacted soil.
Legumes as food
Legumes are a high protein, high fiber food source. Fava beans, wax beans, lentils, lima beans, and wheat are all just a few of the legumes we eat on a daily basis.
Pests and diseases of legume crops
While the pests and diseases of most legumes are more species specific, nearly all legumes are susceptible to Fusarium wilt. Bean mosaic and powdery mildew are common bean and pea diseases. Stinkbugs enjoy legumes and, what makes them worse is that they can also transmit tomato bacterial spot. Weevils and treehoppers are common pests of legumes.
Adding legumes to your garden or landscape can improve the soil, feed nearby plants, and they provide a delicious harvest. Give legumes a try!
Growing the same plants in the same place each year can be a bad idea.
You can break the life cycle of many soil borne pests and diseases by growing plants from different families in the same beds, at different times, in a process called crop rotation. Intercropping is similar to crop rotation, except that intercropping refers to growing different plants in the same area at the same time. Many false claims have been made about the “companion planting” concept, but the benefits of crop rotation have withstood the tests of time and science.
Benefits of rotating crops
While it may be convenient to grow the same plants in the same place each year, in a method called monoculture, many soil borne pests and root diseases can be thwarted by moving crops around. Also, growing different types of crops in an area can reduce nutrient depletion, and sometimes, growing nothing at all is the best choice.
In agriculture, allowing land to rest is referred to as going fallow. This means nothing is grown - no crops, no weeds, nothing. This period of inactivity starves out many agricultural pests. And, honestly, we all need a break now and then. Having a fallow period is an important aspect of crop rotation.
Traditional crop rotation
In Biblical times, farmers were urged to leave an area to its own devices every seventh, or Sabbatical, year. Other methods have also been tried:
Modern agriculture uses chemical supplements to replenish lost nutrients and counteract soil pests, but this method has its own drawbacks, as many of those chemicals then find their way into our food and water supplies.
Crop rotation goals
The goals of crop rotation are to break the life cycle of soil borne pests and diseases, to control weeds, to increase the amount of nitrogen in the soil, to improve soil structure, and to add organic material to the soil. Depending on what you are working with, different crops will help you reach those goals. The first thing you need to do is to identify the soil borne pests and diseases in your garden.
Common soil pests and diseases
Verticillium wilt and downy mildews are the most common Bay Area soil borne diseases. Phytophthora tentaculata is a new threat to many garden plants. Root maggots and many destructive nematodes, such as root knot nematodes, are the most common pests. Take the time to find out which pests and diseases are affecting your plants. Then, look those troublemakers up and learn what you can about the plants they prefer, which plants are unaffected, and which plants can help eliminate the problem. For example, research has shown that Verticillium wilt, which commonly attacks tomatoes, can be reduced by planting broccoli in the same bed, in the following winter. In the same way, root knot nematodes may not impact corn and onions, but they can devastate berries, grapes, and many fruit and nut trees. Growing members of the cereal grain family, such as wheat or barley, in an affected area can reduce nematode populations.
Planning the right rotation for your garden
The simplest way to incorporate crop rotation is to think of why each crop is being grown. Are you harvesting roots, leaves, or fruits? Simply switching up the type of harvest can be enough to break the disease triangle, just be sure to add in a legume crop for the nitrogen in this most basic rotation. For a more science-based crop rotation, you will need to put on your thinking cap. First, identify each unique planting area. Then, list all of the plants you normally grow in a year. Next, label each plant as nitrogen adding or depleting, also biomass adding or depleting. You will also want to add notations about any particular pests or diseases that affect each plant. Personally, I am a visual learner, so I break out a pad of graph paper and some colored markers for this exercise. I use slips of paper for each plant, and then add color-coding to represent each of the different conditions. Then, I move the slips of paper around on a sheet with each of my planting areas roughly drawn on it. Your method may be very different from mine, but it is worth the effort to find a way that works for you.
Successful crop rotation can result in harvests that are 10-25% larger than crops grown in a monoculture system. While scientists have not yet figured out why this happens, they have named it “The Rotation Effect” and you can put it to work in your garden today!
Thinning young plants gives them the room they need to grow bigger and stronger. And most people have a hard time with this common garden task.
When to thin seedlings?
While most plant thinning occurs in spring, as new tomato, pepper, eggplant, and other seedlings emerge, the Bay Area is lucky to have a second growing season, filled with salad greens, broccoli, and cauliflower, so the need for thinning comes around again each fall.
A difficult task
For many gardeners, the idea of removing perfectly healthy plants does not come easily. Images of lush, ripe tomatoes, peppers, and melons offer so much potential, that we find reasons not to thin our garden plants. Of course, by not thinning, we compromise the health of all the plants. Thinning eliminates competition, leaving plenty of food, water, and sunlight for the remaining plants. This allows them to reach full size and produce larger crops. Proper thinning also provides good air flow, preventing many fungal diseases.
Thinning used to mean yanking unwanted plants out of the ground by their roots. This is no longer the case. Soil science has taught us how important tiny soil microbes are to plant health. Pulling plants out by their roots removes the microbes, as well. This makes it difficult for the remaining plants to get the nutrients they need. Pulling plants out also disturbs the roots left in place, which also slows growth. Instead, thinning is done with pruners or scissors, cutting pants off at ground level. This leaves the remaining root systems undisturbed. Plus, it allows the microbes from the thinned out plant to relocate and assist the plants left in place. Snipped off seedlings can be added to the compost pile or fed to the chickens. Just keep in mind that not all crops are thinned in the same way.
Just how much thinning is needed?
Onions and other root plants need frequent thinning. Other plants, such as leeks and beans, perform better without thinning at all. Large, spreading plants, such as pumpkins, need to be thinned out leaving a single plant every 2 or 3 feet! To understand the best way to thin each type of plant, check your seed packets. That information is usually printed on the label. Use it. They know what they’re talking about. If the seed packet is no longer available, look it up online or ask me in the Comments section. You can often calculate spacing needs based on the expected mature size of each plant.
If you really can’t bring yourself to toss out healthy seedlings, you can always plant individual seeds in peat pots, cell trays, or egg shell halves, or any other item that will hold a small seedling until it can be transplanted. Of course, this method means extra work in other ways, but it does eliminate the need for thinning.
Do your garden plants a favor and don’t procrastinate thinning!
You can grow these tasty nuts in your own backyard, if you have room and patience.
The delicious flavor of pistachios doesn’t come cheap. They are not inexpensive and they require effort to pry from their shells. That being said, pistachios have a protein-rich flavor that begs us to eat just one more, and another, and another.
What are pistachios?
The meat of a pistachio (Pistacia vera L.) is not technically a nut. Like apricots, olives, cherries, coconuts, and mangoes, pistachios are drupes, or stone fruits. Pistachios are the edible seeds held within a hard shell. When these seeds ripen, the shell pops open with an audible pop.In the world of botany, the thing that makes a drupe a drupe is that the fruit develops from a single ovary.
How do pistachios grow?
Pistachio trees need long, hot, dry summers and gentle winters to produce those hard-shelled nuts. Pistachio trees can tolerate a lot of salinity, but they do not grow well near the California coast, due to the lack of adequately hot, dry summers. Soggy soil will kill your pistachio tree, so good drainage is critical. Pistachios are a slow-growing, alternate bearing, deciduous tree that needs 600 to 1500 chill hours, depending on variety, to produce fruit. Those chill hours can be hard to come by in the Bay Area, but the trees are lovely and some varieties can be very productive. A healthy, mature pistachio tree can produce 110 pounds of seeds every other year. That’s a lot of pistachios
The following cultivars have been shown to produce well in the south Bay Area:
Pistachio trees are dioecious. That means there are both male and female trees. You only need one male for up to 10 females for successful pollination, but these trees get rather large, so you probably won’t have room for more than one of each. Mature trees can reach 33 feet in height and should be spaced 20 feet apart.
How to grow pistachios
Plant pistachio rootstock from January through early May. Be sure to provide support by inserting a large, heavy stake next to the root ball. You will want the wind to push the tree toward the support for the best development. Irrigate the root ball immediately and follow with regular waterings until the root system is established. This may take several months, so be patient. Your pistachio tree will also need to be fertilized regularly. During the first dormant season, cut the top of the main shoot off, just above leaf buds. This heading cut will promote a solid structure later on.
Pistachio pests and diseases
A disease called panicle and shoot blight, caused by the Botryosphaeria fungi, kills flowers and young shoots of pistachio trees. In 2011, 50% of the Australia pistachio harvest was lost to anthracnose. Verticillium wilt can also be a problem. Severe drought has also reduced commercial production in many areas. Common pistachio pests include leaf-footed bugs, mealybugs, nematodes, and late season navel orangeworms.
After waiting for 5 to 7 years, you will finally be able to harvest your very own pistachios. Like almonds, this is done by shaking the tree. Ripe nuts fall and are collected from the ground. If you see any nuts with mold, toss them in the trash. That particular mold is carcinogenic. Also, be sure to dry your pistachios out completely before storing - they have been known to spontaneously combust.
Don’t let all those problems discourage you or scare you off. These beautiful trees can produce an edible crop for decades, if cared for properly.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.