There are vegetables that we call fruits, nuts that are fruits, and fruits that are not fruits at all! Before we get started, let’s look at why plants go to all the trouble to produce fruit in the first place.
​
How fruit benefits a plant
​
In the world of plants, reproduction is the name of the game. Characteristics that evolve to promote the likelihood of a plant surviving are passed on to the next generation. Fruit is one of those characteristics. Creating fruit takes a lot of energy from a plant. But the fruit we eat has evolved to protect, disperse, and feed the seeds within. As the fruit ripens and falls, the fruit provides protection and nutrients. Fruit also encourages birds, animals, and people to spread seeds farther than the plant could do alone.

Fruit specs

For something to be a botanical fruit, it must be the fertilized ovary of a flowering plant (angiosperm). After pollination and fertilization occur, two new structures are produced: seeds (fertilized ovules) and pericarp (thickened ovary walls). There are three different types of pericarp tissue: exocarp (outer skin), mesocarp (flesh), and endocarp (inner layer). The dominant pericarp tissue can become hard, as with nuts, or fleshy, as we see in peaches and avocados. In some cases, we eat the pericarp. In others, we eat the seed. When we eat the pericarp, we call it a fruit. Sometimes.

Fruit classification

Like most things in life, the more we learn, the less simple anything is. Fruit is no exception. Fruits can be simple, multiple, or aggregate. Rather than going too far down that rabbit hole, let me summarize by saying simple fruits, such as apples and tomatoes, develop from a single ovary. Pineapples and figs are multiple fruits, which form when separate flowers cluster together. Aggregate fruits, such as raspberries and blackberries, are clusters of multiple ovaries from the same flower. Make sense? But wait! There's more! To start, simple fruits are also classified as either dry or fleshy.

​Dry simple fruits

Dry simple fruits are not the shriveled backpacking fare variety. Dry fruits are made up of dead cells that either split open (dehiscent) or stay closed (indehiscent). Dehiscent fruits include hazelnuts, walnuts, pecans, sunflowers, corn, and wheat. Indehiscent fruits include beans and peas and other legumes, dill, poppies, and even cotton!

Accessory fruits and non-fruit fruits

There are also accessory fruits, which are made not just from the ovary, but also from nearby tissues. Common accessory fruits include strawberries, rose hips, apples, and pears. We may as well run the gamut with this one. Rhubarb is considered a fruit, but we only eat the stems, which are technically vegetables.

Getting the best fruits from your garden

Healthy plants produce bigger fruit. Keep your plants healthy with regular inspections for pests and diseases, appropriate watering and feeding, regular pruning, and disposing of mummies as soon as they are seen.

As your fruit starts to ripen, you can make it sweeter by reducing irrigation.

Why has someone wrapped the stems of our bananas? It’s all about the gas!

Put ethylene gas to work for you

​Placing a piece of fruit in a paper bag allows you to take advantage of ethylene gas. The paper holds the ethylene gas closer to the fruit, speeding the ripening process. Plastic bags do not work, as they trap moisture that can lead to rotting. To slow the ripening of neighboring fruits, many sellers place waxed cloth or plastic over the stem end of bunches of bananas.

Other sources of ethylene
​
Ethylene gas is not just from plants. It is manufactured for agribusiness. It is also the byproduct of your car’s engine, natural gas leaks, welding, and some manufacturing processes. The discovery of ethylene gas occurred over 100 years ago, when someone noticed that trees growing near gas street lamps kept dropping their leaves faster than other trees. 

Maybe that’s why my store-bought strawberries go from nearly perfect to inedible overnight.

Catfacing refers to the deep, puckered ridges, filled with coarse brown skin, that can occur on your tomatoes, usually on the bottom. Cracking is something altogether different.

Furry carrots? Twisted roots? It might be aster yellows!

Aster yellows phytoplasma (AYP) is a disease transmitted by leafhoppers and root-knot nematodes. It gets its name from the family of plants affected (carrots and sunflowers), the symptoms (yellowing), and the bacteria that causes it (phytoplasma).

Aster yellows can affect all Aster family members, including celery, onions, coriander, caraway, and lettuce. Purple coneflower, marigolds, and coreopsis can also be infected.

Losses of 25 to 80% occur in commercial crops due to aster yellows. Quarantining new plants is the easiest way to prevent aster yellows from occurring in your garden or greenhouse. (I know it’s hard to wait ~ but some diseases never go away.)

The bacteria that cause this disease reproduce in leafhoppers, root-knot nematodes, and the phloem of susceptible plants. These bacteria help leafhoppers and nematodes live longer, but the opposite is true for our plants. As bacterial populations grow, they block the flow of sap, water, plant hormones, and nutrients within our plants, causing chlorosis (yellowing) and distortion.

​Poison hemlock population explosion

Poison hemlock often grows alongside creeks and in locations with shade and moist soil. Many areas, including Cupertino’s McClellan Ranch Park and the Trukee River, see population booms after wet winters. Seeds (of many different plants) that had been dormant for several years use that moisture to germinate, rushing to reproduce. Just don't be fooled by this deadly plant's delicate appearance.

Just as the “leaves of three, let it be” rhyme has provided years of protection from poison ivy, try embedding this rhyme in your brain to help you stay away from poison hemlock:

If you suspect poisoning from this plant, call Poison Control immediately at 1-800-222-1222. A quick response can save a life.

UPDATE:

Thanks to John, curator at the Carrot Museum,  I have learned that poison hemlock, for all its toxicity, is also used as a medicine. Seeds, roots, and leaves, when handled properly, can be used to treat respiratory conditions, such as whooping cough, asthma, and bronchitis. Poison hemlock has also been used to treat painful joints, to counteract anxiety and epilepsy, and to reverse strychnine poisoning.

Inchworms fascinated us as children. We watched their measured steps with front legs, followed by back legs, giving them the characteristic arching motion. 

Inchworms, also known as loopers, span worms, and measuring worms, aren’t worms at all. They are the larval form of Geometer moths. The Latin name, Geometridae, means to measure the earth.

Inchworm description

​Inchworms are generally smooth, hairless, and about an inch long. (Big surprise, right?) Inchworms have 3 pairs of true legs in front, like other caterpillars, but only 2 or 3 of pseudo ‘prolegs’ in back. Depending on the parent moth, inchworms can be brown, green, or black, and some have vertical racing stripes. Some species have camouflaging projections that make them look like twigs. When disturbed, they hold themselves upright, reinforcing that image. Most adult moths have slender bodies and wide wings that are held open when resting, similar to most butterflies. They tend to be a little over an inch wide and have intricate patterns on brownish wings. The antenna of males are often feathered.

The life of an inchworm

​Inchworms start out as the eggs of Geometer moths, laid on the underside of leaves. In spring, the eggs hatch and inchworms start feeding, usually at night. It is this feeding that can cause some conflict between inchworms and gardeners, but we’ll get to that in a minute. Inchworms eat so much that they outgrow their skin and have to molt several times before they’ve eaten their fill. Then, they build a hard shell around themselves where they can pupate into adult moths.

Types of inchworms

Some inchworms, called omnivorous loopers (Sabulodes aegrotata), are particularly fond of avocados. Others, called cankerworms, are particularly destructive to plums and prunes. There are two varieties of cankerworm: the spring cankerworm (Paleacrita vernata) and the fall cankerworm (Alsophila pometaria). Some claim that English sparrows were first introduced into North America to check spring cankerworm populations in Central park, back in the mid-1800’s. Whoops. (When will we learn???) Actually, the St. Johnswort inchworm (Aplocera plagiata) was introduced to California in 2014 to help stop the spread of Canary Island hypericum. We’ll have to wait and see how that one backfires.)

Host plants

There are over 35,000 different types of inchworms worldwide and 1,200 different kinds in North America. Each type of inchworm has a favorite food, or host plant. Common host plants include:

• blueberry spanworms
• Bougainvillea looper (Disclisioprocta stellata)
• cabbage loopers (Trichoplusia ni)
• California oakworm (Phryganidia californica)
• cranberry inchworms
• spruce spanworms

Inchworm damage

A single inchworm won’t cause noticeable damage in the garden, but a bunch of them can wipe out some of your favorite crops. Inchworms generally feed on tender new shoots, fruit, and the edges of leaves, creating a scalloped effect. When disturbed, some inchworms quickly spin a silken thread from their mouth and repel out of danger. Even if you do not see the culprits for yourself, you may see the dark fecal pellets (frass) they leave behind.

Respiration probably isn’t what you think it is, especially when it comes to plants.

Most of us think of ‘respiration’ as the breathing in and out that we do to oxygenate our blood. But that’s only part of the story. Respiration refers to any process within a living thing that uses a gas exchange to generate or release energy.

Plant respiration

Plants respire through root hairs, outer stem cells, and tiny holes on the underside of leaves called stomata. The stoma can be opened for respiration or closed to conserve water. [In extreme heat, plant respiration can be reduced by as much as 50% due to stomata closure.] The oxygen that enters through the stoma then moves to individual plant cells, where it is used in several different cellular functions. These chemical reactions produce carbon dioxide, which is released by diffusion. Iron and potassium are important components of this process.

Respiration as energy production

We all know that plants absorb water through the roots and create sugars in the leaves using photosynthesis. Those sugars travel through the phloem to the mitochondria of most plant cells, where they are oxidized, or broken down, by oxygen molecules. The oxygen breaks the sugar molecules into carbon dioxide, water, and storable energy, called ATP (adenosine triphosphate).

Respiration and photosynthesis

Everything switches while photosynthesis is taking place. When a plant is actively producing energy from light, carbon dioxide is inhaled and converted into sugar, and oxygen is exhaled. This is called the Krebs Cycle. This means that your plants are providing you with oxygen during the day, and taking it back at night. Thus, the Eternal Balance of oxygen and carbon dioxide in nature is maintained.

You may be surprised to learn, as I was, that respiration without oxygen (anaerobic) is called fermentation. When plants try to respire without oxygen, they make alcohol!​​

Summer and winter squash

There are two types of squash: summer squash and winter squash. This has nothing to do with when they are grown. Instead, it is more about when they are eaten. Winter squash, such as pumpkins, butternut squash, and acorn squash, have hard outer shells that make them easy to store. Summer squashes, such as zucchini and yellow crookneck squash, have softer skins and must be eaten (or preserved) sooner.

Summer squashes tend to have bushier growth than winter varieties, but most squash plants can really spread out, so don’t plant more than you have room for in the garden.

​How to grow squash​

You can leave last fall’s pumpkin to go through the natural cycle of withering, collapsing, rotting, resting, and sprouting, or you can start with seeds. ​

Squash seeds are large and flat and should be planted 1” deep. Squash plants do not respond well to transplanting, so it is best to start them where you want them.

Since these plants take up some room, they are often grown in ‘hills’. These hills are usually 6-8” high and 12-24” wide and can support two or three plants. Squash seeds planted in rows should be 18 to 30 inches apart, depending on the variety. Squash can also be grown in containers, raised beds, and towers.

Squash plants are rugged and they thrive in hot, dry summers. They are heavy feeders, require frequent watering, and they prefer a soil pH of 5.5 to 7.5. Digging in some aged compost or manure when creating the hills will go a long way to ensuring a good harvest. Once these plants are established, they need nothing from you but water. During the peak of summer, afternoon wilting is normal and not cause for concern. Plants will need to be watered deeply once or twice a week, depending on the weather. Mulching around plants can reduce the need for water and it stabilizes soil temperatures.

How squash plants grow

As they grow, they create both male and female flowers. These flowers are usually yellow or orange, and the male flowers tend to emerge first. These flowers are edible, but eating the flowers means no fruit. Since there will be some female flowers emerging after all the male flowers have disappeared, you can boost your crop by cutting off and bagging the male flower anthers, which hold the pollen, and applying the pollen to later female flowers with a natural hair paint brush. In the same way, if there are not enough pollinators in your area, you can hand pollinate squash flowers. In fact, research has shown that applying pollen to female flowers manually causes larger fruit that is more likely to reach maturity. Also, the seeds within that fruit germinate faster and produce larger seedlings. This is called the xenia effect. As fruit is produced, many growers place a layer of straw underneath to reduce soil contact and the potential for fungal problems.

Squash pests and diseases

As always, aphids, cutworms, earwigs, leafhoppers, grasshoppers, leafminers, mites, whiteflies, wireworms, and thrips will lust after your squash plants. (It’s really a wonder that anything grows at all, but grow it will!) Squash bugs, squash vine borers, and cucumber beetles cause the most squash problems. Cucumber beetles can also carry wilt disease. Placing row covers over seedlings and dusting plants with diatomaceous earth can reduce pest populations organically. Powdery mildew and downy mildews, anthracnose, verticillium wilt, root rot, curly top, bacterial wilt, scab, and mosaic diseases can be reduced by planting resistant varieties, avoiding overhead watering, keeping the garden clear of any diseased leaves (and not adding them to the compost pile), and using crop rotation.

Harvesting squash

Squashes should be harvested by cutting the vine with a sharp knife about one inch above the fruit. Do not twist or yank at it, as this can damage the plant. Summer squashes are best harvested young and eaten fresh. Of course, if you just can’t take another zucchini stir-fry, or you discover a specimen the size of a horse leg, you can always treat yourself to some chocolate zucchini cake or stuff it with some sausage and bake it. You can also cube, blanch, and freeze summer squash for use in soups and stews, but it tends to disintegrate. Winter squash, on the other hand, can be stored in a cool, dry, shaded area, such as a garage, for several months. I’ve had butternut squash that lasted nearly two years and tasted just as sweet and flavorful as fruit from the same vine that was eaten a year before.

Healthy squash plants can produce an astounding amount of food. This makes them an excellent Plant It Forward addition to your garden or landscape.​

Tomato russet mites are too small to see without a 14X lens, but the damage is easy to recognize.

Symptoms of tomato russet mite infestations

​The first symptom of a tomato russet mite infestation is leaf stippling (yellow dots), which spreads to include the entire leaf. Leaves will then begin to curl and turn, you guessed it, russet colored. Stems and fruit also develop the same rough brown skin, and flower abortion is common. Symptoms usually start near the bottom of the plant and work their way up. Left uncontrolled, these pests can kill your tomato plant.

​More about mites

Mites have piercing mouthparts that are used to poke holes in a plant’s epidermis and to suck the life juices out of leaves, stems, and fruit. Like other mites, tomato russet mites (Aculops lycopersici) are more closely related to spiders than to other insects. They have eight legs and start out as an egg. These eggs are usually laid singly on the underside of leaves, in areas of new growth, cracks, or near pipes. When the eggs hatch, the larvae only have two legs. Then they go through two nymph stages. Unlike other common garden mites, tomato russet mites are in a separate family called gall mites. Gall mites are unique in that they create galls where they feed. The real problem with tomato russet mites is that they are so tiny (0.2 mm long and 0.05 mm wide); you can’t see them until the damage is extensive.

Mite controls

Mites love hot, dry conditions. They also seem to like dust, so keeping your plants relatively dust-free can reduce mite problems. Misting has also been shown to deter mites. These pests have many natural enemies, including predatory mites, predatory flies, and ladybugs. For this reason, broad spectrum pesticides should be avoided. These pests have demonstrated the ability to develop resistance to pesticides, so we don’t want to make them any more destructive than they already are! Sulfur dust and sulfur sprays can be used to get rid of mites organically.

Monitor your tomato plants weekly for signs of tomato russet mite infestation. Symptoms usually appear when the green fruit is 1 inch in diameter. Catching this pest early can save your plants!

​Fertilizer isn’t just NPK

Most gardeners are very familiar with the NPK found on most bags of fertilizer. These letters represent the three primary macronutrients needed by plants: nitrogen, phosphorus, and potassium, respectively. Of course, what you mostly get when you buy fertilizer is filler. A 20-pound bag of 10-10-10 fertilizer actually contains 10%, or 2-pounds, of each element. The remaining 14-pounds is just filler. Plants also use calcium (Ca), magnesium (Mg), and sulfur (S) as secondary macronutrients. Plants also need these micronutrients: copper (Cu), manganese (Mn), zinc (Zn), boron (B), and iron (Fe).

​Nutrient movement within plants

Some plant nutrients are highly mobile. This means they can be moved around, within a plant, to where they are needed. Nitrogen is so mobile that you can identify nitrogen deficiencies in the soil by looking at the leaves. Older leaves will begin to turn yellow as nitrogen is pulled away to make fresh, bright green, new leaves. Iron, on the other hand, is relatively fixed once it enters a plant. Older leaves will stay green, but new leaves will be pale or look bleached.​​

​Iron deficiency symptoms

Plants grown in iron deficient soil often turn yellow and they cannot thrive because they are starving. This is because iron is needed to produce chlorophyll and in plant respiration. [Note: plant respiration is not the same thing as mammalian breathing - plant respiration refers to breaking down stored food reserves to release usable energy into the plant.] Yellowing (chlorosis) due to iron deficiencies normally begins in the areas between leaf veins, which stay green. Young leaves may look bleached. Symptoms are more pronounced in acid-loving plants, such as blueberries, raspberries, and camellias. Over time, leaf size will be reduced, and dead (necrotic) patches will appear along leaf edges (margins) and between veins. Leaves will also die and drop prematurely. Shoots and canes can also die back.

Iron and soil pH

Often, you will see the word ‘chelated’ on a soil amendment that includes iron. This is because free iron molecules can become unavailable to plants when pH levels are not between 5.0 and 6.5, or when phosphate concentrations are out of balance. This balancing act has to do with the way micronutrients interact with each other in the soil. If they bind to one another, plants can’t get to them. This is particularly troublesome in our highly alkaline, compacted clay soil.

Other causes of iron being unavailable to plants include soil that has been waterlogged (due to flooding or a leaking sprinkler), or too many other nutrients. High levels of copper, manganese, phosphorus, calcium, or zinc will bind to the iron, making everything unavailable to plants. This is a case where adding fertilizer just makes things worse, rather than better.

Case in point

I have a beautiful yard and I love to garden. We moved here in 2012. There were several fungal disease problems present, as a result of leaky and poorly placed sprinklers. The soil is heavy clay and compacted. Borers, scale insects, and aphids were problematic. We stopped using the sprinklers and switched to soaker hoses. Then we started adding compost and mulch to the landscape. And I sent a soil sample to a lab for testing. The results were educational, to say the least.

My soil had an excess of every nutrient, except iron. My soil’s iron levels were far below the recommended level, making every other nutrient unavailable to my plants. As a result, the plants were not healthy enough to fight off pests and diseases as well as they would have been otherwise. Without that soil test, I might have added even more fertilizer, making things even worse for my plants. I can’t stress this enough: get your soil tested by a reputable, local lab. The information is invaluable.

Counteracting iron deficiencies

If your soil is low on iron, you can jump-start your plants’ health with a foliar spray of iron. Spraying leaves with chelated iron or ferrous sulfate allows plants to absorb the mineral directly through leaf tissue. Once the iron is inside the plant, other nutrients can be used. This treatment will need to be repeated as new leaves emerge. Also, it should not be done during hot weather, and it might stain your patio. Longer term solutions include:

• selecting plants that will thrive in the soil (and microclimate) you already have
• acidifying the soil with iron sulfate, elemental sulfur, or ammonium sulfate (which also contains nitrogen) - do not use aluminum sulfate, which can be toxic to root systems
• reducing soil compaction with aeration and mulch
• trunk injections of iron by a licensed professional
• fertilizing the soil with chelated iron

These treatments should only be done AFTER a laboratory soil test has indicated that iron levels are deficient. Over-the-counter soil tests are not effective enough to justify any adjustments.

Everything dies. The programmed death of cells within a plant is called apoptosis.

Sooner or later, the end comes for all living things. In the world of plants, the timing of death is used as a major classifying factor. That’s why we say a plant is perennial, annual, or biennial. Within the world of plants, there are three types of death:

• necrosis - uncontrolled method of death, such as being stepped on, or hit by a car
• autophagy - ‘self-eating’; the absorption of a plant’s own tissues leading to death
• apoptosis - planned release of certain proteins that cause the uninterruptible death of a plant

Annual, biennial, and perennial

Annual plants complete their entire life cycle in one growing season. That may sound like a raw deal, but the male luna moth only gets three days and no mouth. (See, perspective is everything.) Within an annual plant’s DNA is a series of instructions that drive the plant to produce seeds for the next generation before the seasons change for the worse. Biennials get a two year cycle to accomplish the same ends. Perennial plants are, well, perennial. They keep on going. Some perennials last 10 to 20 years, or upwards of 50, in the case of most fruit and nut trees. Some perennials, however, have seen the coming of electricity, Christ, and even the Bronze Age, and the invention of writing! If you count clones as the same plant, there is one Tasmanian shrub, King’s lomatia (Lomatia tasmanica), that has been around for somewhere between 43,000 and 135,000 years! It boggles the brain. Even these ancients will eventually succumb to senescence. Senescence refers to the stage in a plant’s life when its metabolism slows prior to death.

The process of apoptosis

The programmed cell death of a plant begins with instructions from the mitochondria, activating certain proteins, called caspases. These proteins trigger other proteins that lead to cell shrinkage, bulging (called ‘blebbing’ - how cool is that?), and fragmentation of the nucleus and DNA. The individual cells technically commit suicide in response to predetermined growth and survival factors.

The end is nigh!

So, what does all this have to do with your garden? First, understanding that some plants are preprogrammed for a short life, you can select the plants that best suit your purposes. Do you want trouble-free perennials, such as rhubarb and asparagus, that will come back, year after year, or do you prefer the more tender annuals of cucumber, peppers, and corn? Taking into account a plant’s lifespan can help you to design your garden and landscape more effectively.

And, hey, with words like blebbing and senescence, your friends are sure to be impressed!

​Jay bird damage​

If you have fruit or nut trees, you have already battled jays. These orchard pests will peck a large chunk out of several different pieces of fruit, rather than eating one at a time. This damaged fruit rots more quickly and it leaves the trees vulnerable to other infestations and infections. In the U.K., there are several very nice tree netting systems, but I have not found anything nearly as effective here in the U.S. (If you know of a supplier, please let us know in the Comments!) Jays can wipe out your berry, corn, pea, and grape crops. They can also carry West Nile virus and avian pox.

Jay bird controls

According to D. Whisson and M. Freeman, of UC Davis, “Jays are classified as migratory non-game birds according to federal regulations. They can only be controlled under a permit from the USFWS. Shooting is a possible control measure but is very labor intensive. Frightening devices are relatively ineffective. Trapping with rat traps using nuts as bait can be effective for a small number of birds.” Of course, in the Bay Area, shooting is not an option. You can avoid using bird seed mixes that attract jays and squirrels in bird feeders. My dogs like to chase the scrub jays away, but it is a very temporary fix.

Probably the most humane scrub jay control is to provide a distracting food source that fulfills their needs enough to reduce the potential for garden damage.

Sweet, luscious pineapple - try growing it at home!

If you are lucky enough to live in California, you might be able to grow a pineapple plant for yourself. While you may or may not get fruit, it’s an interesting experience and, hey, it just might work! (Plus, three-fourths of the world’s pineapple crop comes from Costa Rica, where they use a lot of pesticides. Just sayin’)

​Pineapples got their name back in the 1600s because European explorers thought they resembled pine cones, which were called 'pine apples' at that time. The Latin names, Ananas comosus, mean ‘excellent fruit’ and ‘tufted’, respectively. Pineapples are cousins to bromeliads, and the fruit are technically berries.

When a pineapple seed is pollinated, the fruit isn’t considered marketable. In Hawaii, where the majority of pineapples used to be grown, hummingbirds could not be imported, for fear that they would pollinate all the pineapples. There are some wild pineapple plants that only flower at night and these are pollinated by bats. 

How to start your own pineapple plant

You can try growing your own pineapple from the crown of a mature fruit. Simply follow these steps:

1. Wash the pineapple thoroughly to remove pests, chemicals, and other nasties.
2. Slice off the top part of the fruit, or the crown, removing layers until a circle of brown spots are seen. These spots are root buds.
3. Pull off enough leaves to expose and inch or so of the stalk.
4. Let it dry out for several days, up to two weeks. This is important.
5. Place the crown gently into/on top of loose soil and water lightly.
6. Water regularly, allowing the soil to dry out between waterings.
7. Monitor for rooting.
8. Repot, as needed.

Fir bark mulch is made from the chopped or shredded bark of conifers, such as redwood, pine, and fir.

Fir bark mulch is just one of several different types of mulch you can use to reduce erosion, crusting, and soil compaction. Mulch also helps retain moisture, reduce weeds, and it stabilizes soil temperature. As it breaks down, it even adds nutrients to the soil. Mulch can be straw, grass clippings, compost, wood chips, or fir bark. Fir bark and wood chips last a lot longer than the other mulches. 

Which is better for your landscape: wood chips or fir bark?

Grades of fir bark mulch

Fir bark mulch comes in a variety of sizes, or grades: 

• finely shredded, often called gorilla hair
• mini bark - 1/4” to 1/2” pieces
• small bark - 1/2” to 1-1/2” pieces
• medium bark - 1” to 2” pieces

The larger the pieces are, the bigger the spaces between them will be. These spaces allow air and water to flow through. Tiny pieces of mulch will hold more water in the soil, but allow for less gas exchange. Yes, it is a balancing act. The biggest thing to consider with fir bark mulch is the likelihood of flowing water in the area. Fir bark has a waxy coating that prevents it from absorbing water, plus it is very light, so it will simply float away. Wood chips, on the other hand, will absorb the water and are more likely to stay where they are.

Calculating coverage

To determine the cost of using fir bark, you will first need to calculate the area to be covered, and then deicide the depth of coverage needed. Generally speaking, mulch should be 2” to 4” thick. Newly developed areas should be given 3” to 4” of mulch, while established areas can often do with less. One cubic yard (27 cubic feet) of medium sized fir bark will cover an area of 324 square feet to a depth of 1 inch. Let me say it again:

As an example, let's say you have two areas that are 40 feet long and 3 feet wide, and one area that is 30 feet long and 2 feet wide. Here are the initial calculations:

    = [2 (areas) x 40 (feet long) x 3 (feet wide)] + [1 (area) x 30 (feet long) x 2 (feet wide)]
    = [2 x 40 x 3] + [30 x 2]
    = [80 x 3] + [30 x 2]
    = 240 + 60
    = 300 square feet

In our example, one cubic yard of medium fir bark would give us a little more than one inch covered, since we only need 300 square feet and cubic yard provides 324 square feet. If we decide to use a 2 inch layer, we would need a little less than two cubic yards of fir bark. If you are a number nerd, like me, you could calculate the exact amount needed for a 2 inch depth (1.85 cubic yards), but that really isn’t necessary because a little extra is fine, or you can use it to top off your container plants.

Cost of fir bark mulch

Currently, in the Bay Area, prices for fir bark mulch average $67 per cubic yard, plus an average delivery fee of $77. A few suppliers will offer free delivery if you buy more than 7 cubic yards, but that is more than most of us will ever use. Some suppliers will also let you pick up fir bark in bags or trucks, so you can save money that way. Of course, it also means you will be picking up all that mulch One More Time. (After moving a full dump truck load of wood chips from my driveway to the back yard using a wheelbarrow, back and forth over 100 times, I can tell you that it feels like an ordeal after a while!)

Nitrogen loss (and gain)

If you use freshly chipped wood mulch of either type, keep in mind that it will, for the first 6 to 8 weeks, pull nitrogen from the soil as is begins to break down. You may need to add a little extra nitrogen during this time. In the long term, as the wood continues to break down, it will add nitrogen to the soil.

Fir bark provides an attractive, durable, and protective covering for your soil, but wood chips are free and less likely to give you splinters.

The fiery bite of horseradish adds its signature flavor to many dishes, and it also makes a nice patio plant.

Horseradish (Armoracia rusticana) is a member of the Brassicaceae family, making it cousin to watercress, mustard, wasabi, radishes, broccoli, turnips, and cabbage. Scientists used to call these types of plants Cruciferae. The word cruciferous refers to the flowers, which have four petals, resembling a cross. Supposedly, the Oracle at Delphi told Apollo that horseradish was worth its weight in gold, so it’s been around for a really long time. Today, let’s learn how easy these plants are to grow at home. ​

How horseradish grows

The horseradish that you buy in the grocery store is usually peeled, pureed, and pickled. Grown for its root, horseradish plants can grow over 4 feet tall, but mine have never gotten bigger than a couple of feet all the way around. Horseradish needs a long growing season to get started. They also need a chilly winter to induce dormancy. We have both, here in the Bay Area. Horseradish plants spread underground and can become invasive, which is one reason why they make good container plants. As they age, roots become woody and unusable as food, but they can still be used to start new plants. The first leaves usually look distinctly different from the normal large lobed, tapered, or heart-shaped  leaves, so don’t pull them out by accident!

Horseradish as food

Roast beef, Bloody Marys, and salmon are always made better with horseradish. You can buy ‘prepared’ horseradish, which contains grated root and vinegar, or you can buy ‘horseradish sauce’, which adds mayonnaise. Growing your own horseradish allows you to create a unique recipe of your own. But, when you first dig up your horseradish root, you may feel as though you did something wrong. The root itself has no smell. It isn’t until the root is chopped up that certain enzymes are released. These enzymes break down plant tissues, producing mustard oil.

​It is the mustard oil that lights up your sinuses when you take a bite. Chopped or grated horseradish turns brown and bitter when left untreated, which is why vinegar is always added as a preservative. The longer chopped horseradish sits before the addition of vinegar, the hotter it gets. Whether you grow your own horseradish or buy it already prepared, you really should try this recipe for remoulade. Your tastebuds will thank you! Horseradish leaves are edible, as well. Use them sparingly in a salad for the same fiery bite you get from the root.

Horseradish pests and diseases

Cabbageworms, leafhoppers, and aphids may feed on your plants. Horseradish is also susceptible to viral diseases, such as beet curly top (rhabdovirus group) and turnip mosaic (potyvirus group). These diseases are spread by leafhoppers and aphids, respectively.

Did you know that, when you buy wasabi, what you are probably really getting is horseradish? Wasabi plants are becoming scarce and horseradish is easy to grow. Manufacturers use the fact that these plants are closely related to mislead their customers. (Shame on them!)

You can add a horseradish plant to your patio, balcony, or garden for lovely spring and summer greenery, and year round flavor!

Native to Canada and the northeastern U.S., apple maggots (Rhagoletis pomonella) originally lived and fed on hawthorn trees and fruit. Apples were introduced to those regions in 1710, but no mention of apple maggots was made until 1860, when infestations became heavy. Apple maggots have slowly spread across the country, reaching Oregon in 1979. Four years later, 101 flies in 38 orchards were found in California apples. Today, apple maggots are found practically everywhere in North America, which the exception of a few valleys in British Columbia. Being responsible for millions of dollars of crop losses each year, apple maggot quarantines are in place in several California counties.

Identification

​Adult apple maggot flies are frequently mistaken for spiders, at first glance. Disturbed adults will turn their wings 90-degrees and move their body up and down while walking sideways. Why they don’t simply fly away, I’ll never know. Flies are less than 1/4” long, dark, with white stripes, a white dot on the middle segment (thorax), and yellow legs. The wings have black bands that look like a capital “F”. The head is yellowish and the eyes can be green or dark red. Larvae are white, legless, and 1/4” long, with two dark mouth hooks. The pupae are tan to dark brown hard cases found in the soil.

Apple maggot lifecycle

A female fly will lay up to 500 small, white eggs, each on a separate fruit, under the skin of apples, cherries, apricots, plums, pears, wild rose, Pyracantha, and crabapples. The maggots, or worms, will stay inside their host fruit, safely feeding until the fruit falls from the tree. The fattened larvae then burrow into the ground where they pupate in the soil over the winter. Adult flies emerge June through September and then feed on honeydew and bird poop. Yuck!

Apple maggot damage

You may see small dimples where eggs have been inserted under the skin of vulnerable fruits. From there, the larvae go unnoticed as they feed, until you take a bite. Then, brown tunnels and a (hopefully!) intact larvae can be seen. You can tell the difference between apple maggot and codling moth damage because codling moth larva prefer apple cores, while apple maggots prefer the fruit. Personally, I don’t want to see either one in my apple!

Apple maggot control

Apple maggots have many natural enemies, such as parasitic wasps, so broad spectrum pesticides should be avoided. Since the larvae are safe once inside the fruit, pesticides won’t work anyway. Instead, sticky traps can be used. These traps are usually a red sphere, like an apple, or a bright yellow panel. I”m not sure why so many insects are attracted to yellow paper, but it seems to be pretty common.

These are not pheromone traps, which can attract pests from several yards away. Instead, a protein-ammonia mix is used and it is only effective in the immediate area. These traps should be hung in the outer third of the tree canopy, in an open area. You may need to remove nearby foliage, up to 18 inches from the trap, to make it more visible (and alluring) to apple maggot flies. You can buy these traps at garden centers and they should be inspected every few days and replaced every 2 to 3 weeks, depending on how messy they get. The spheres should be cleaned and re-stickied every 4 weeks. If you catch any apple maggot flies in your traps, you really should contact your local County Extension Office or the Department of Agriculture. You can also participate in a fun civilian project called The Big Bug Hunt, which uses our inputs to create a warning system that alerts you when insect pests are headed your way. It’s pretty neat.

By monitoring where this pest is seen, the proper quarantines can be put in place to reduce the damage. If apple maggot flies are trapped, the traps should be kept in use until no more flies are trapped.

Protect your apple and other crops by monitoring for this relatively new pest.

Zucchini is a summer squash that can sneak up you.  Large, prickly (edible) leaves shade the ground and defend against insects. They also hide the occasional zucchini, allowing it to reach horse leg proportions. In Britain, they call these epic squash ‘marrows’, but zucchini are generally harvested when much smaller and younger.

According to Guinness World Records, the longest zucchini on record was over 8 feet long and the heaviest weighed in at over 64 pounds! Holy smokes! Imagine stuffing one of those monsters! Before our zucchini ever reach those proportions, let’s learn more about how they grow and how we can help them be flavorful and productive.

How zucchini plants grow

Zucchini are members of the squash family, making them cousin to pumpkins and melons. Botanically, zucchini are berries - isn’t science fun? Adding zucchini to the garden or landscape is an excellent way to grow your own food. Like other gourds, zucchini have both male and female flowers. Both flowers are edible, with the pistil and stamen removed. Zucchini flowers can be deep fried, baked, sautéed, or added to soups or salads. Personally, I’d rather have the more substantial produce, so I leave the flowers alone. Honey bees and other pollinators are needed, so avoid using broad-spectrum pesticides near zucchini plants. If there are not enough pollinators, you can always hand-pollinate.

Growing zucchini

Zucchini is a very forgiving and productive plant and it loves warm, sunny weather. You can grow zucchini in large containers, straw bales, towers, raised beds, or in the ground. Seeds germinate best at 70° to 95°F and should be planted one inch deep. You can plant seeds individually or in hills. Individual plants should be spaced 3 feet apart. Hills (6-8” high and 12-24” wide) can support two or three plants. Zucchini plants do not handle being transplanted very well and they will benefit from a layer of mulch. Be sure to irrigate regularly. Water-stressed zucchini, and other squash, will taste bitter. This bitterness is caused by toxins that can be potentially dangerous. Don’t let this scare you off, just be sure to water your zucchini plants regularly. This will also help prevent blossom end rot.

Zucchini pests and diseases

Sporadic watering and insufficient calcium can cause blossom end rot in zucchini. Overhead watering can cause powdery mildew, downy mildews, and white mold, so irrigate regularly with soaker hoses. Other diseases include curly top, damping-off, fusarium crown and foot rot, verticillium wilt, and various viruses. Aphids (isn’t it always aphids?), earwigs, cutworms, cucumber beetles, crickets and grasshoppers, slugs and snails, flea beetles, armyworms, nematodes, loopers, leafminers, leafhoppers, thrips, squash bugs, squash vine borers, spider mites, wireworms, and whiteflies will all want some of your zucchini. The good news: you’ll still probably end up with more zucchini than you know what to do with!

Too much zucchini?

Zucchini plants are very productive. While harvested zucchini are very mild and can be adapted to many different dishes, sometimes you just need a change. After you have sautéed, stir-fried, baked, grilled, spiralized, and broiled all the zucchini you can handle, try making some Chocolate Zucchini Cake. This particular recipe has been responsible for transforming the opinions of toddlers, teens, and skeptics for generations. Zucchini can also be pickled, and you can puree it and freeze it for later use. Don’t bother trying to freeze cubed zucchini - it doesn’t end well.

Zucchini and the cross-pollination rumor

Many gardeners worry about cross-pollination between members of the gourd family, but this worry is unnecessary. Natural cross-pollination can only occur within a species (we will not discuss genetic manipulation at the nano surgery level). This means that zucchini plants can cross-pollinate with other zucchini and summer squash varieties, but not with melons or cucumbers. This is actually how we get many new cultivars. When cross-pollination does occur, it has no affect on the current season’s fruit or vegetable. It does alter the DNA within next year’s seeds.

Even if you are a card-carrying Brown Thumb, give zucchini a try this year. It is a very rewarding plant and you can never have too much Chocolate Zucchini Cake!

Soaker hoses are an inexpensive way to add a drip-system to your garden or landscape.

While many gardening aficionados dream of The Perfect Drip System, most of us have neither the time or the money to do so. Also, drip emitters can clog and they require regular monitoring and maintenance. Hm, maybe they’re not so perfect after all, eh? Soaker hoses give similar results for far less money.

How do soaker hoses work?​

Soaker hoses look just like other garden hoses, except they have thousands of tiny holes, or pores, in them. These holes allow irrigation water to slowly ooze out, along the length of the hose, dripping water where your plants need it most.

Hand watering

I know that many of us enjoy a certain sense of tranquility, strolling through the garden, hose in hand, dispensing life-giving water as we go. Unfortunately, hand watering isn’t nearly as efficient as we would like to think. [Next time you hand water, take a trowel to the area and see just how much water actually made it to a root zone.] Also, overhead watering increases the chance of many fungal diseases.

Benefits of watering with a soaker hose

A well designed watering system can use 30 to 50% less water and get better results. Other benefits of watering with a soaker hose include:

• reduced evaporation and runoff
• water goes directly to the root zone
• reduced nutrient loss due to leaching
• the soil surface stays drier, reducing weeds and fungal diseases
• eliminates the need to drag your hose around (yay!)

Choosing the right soaker hose

Like most garden hoses, the majority of soaker hoses currently available contain lead and other potentially toxic chemicals. Many of them are made from ground up old car tires, which doesn’t strike me as very appetizing. While they do cost more, I use food-grade hoses in my garden. Food grade garden hoses are becoming more readily available and prices are slowly coming down as they sell enough of them to cover their costs and make a decent living. They even come in pretty colors! You can find soaker hoses with built in pressure valves and quick-release connectors. You can also find soaker hose systems that allow you to connect segments of soaker hose with segments of regular garden hose for more control. Again, make sure that the materials used are durable and food-grade before you use it to water your tomatoes.

How and where to use soaker hoses

Soaker hoses are generally left in place for the growing season. Snake your soaker hose through your vegetable garden, looping around fruit and nut trees, or among your ornamentals. Soaker hoses are an excellent addition to raised beds and straw bale gardens. These tips will help you get the best results from your soaker hose:

• use very gentle pressure - seep, not spray (most faucets are 50 psi; soaker hoses use 10 psi)
• do not use on slopes
• do not use lengths greater than 100 feet
• space hoses 18 to 24 inches apart (12 to 18 inches for sandy soil)
• provide a few inches of space between the soaker hose and plant stems and trunks
• bury your soaker hose under mulch or loose soil for better results (Just remember where it is before digging!)
• you may want to add a back flow preventer and pressure regulator to the faucet

Leave soaker hoses running until the water has saturated your plants’ root zones. Since each plant is different, you really should use a trowel to see where the roots are and how deep the water is going. Monitor how long it takes for that much watering to occur, and then you can add a timer to your faucet for added convenience. Just remember that as temperatures rise and plants grow, they will need more water.

It is a good idea to flush out soaker hoses a couple of times a year. To do this, simply take the end cap off and turn the water on. It only takes a minute or two. Then be sure to put the end cap back on!

Invest in food grade garden and soaker hoses for better water efficiency and healthy plants.

Distant cousin to guavas, pineapple guava (Acca sellowiana, or Feijoa (fay-zho-uh) sellowiana) is a member of the myrtle family. Native to Brazil and Argentina, it is well suited to the Bay Area’s hot summers and cool winters. It is somewhat frost tolerant. The edible flowers look like tiny versions of bottlebrush and have a cinnamon flavor. (Of course, if you eat all the flowers, you won’t get any fruit!)

Growth habits

Pineapple guava is a relatively slow-growing perennial evergreen shrub that can eventually reach a height and width of 10 to 15 feet. Leaves are green on top and silvery underneath, which looks really nice when a breeze comes through. Pineapple guava plants grow best in USDA Hardiness zones 8 through 11 and they need 50 chill hours each winter to set fruit (I get 300 in the Bay Area). If temperatures are above 90 °F for too long, fruit set can be reduced. Pineapple guava are very drought tolerant, but they do need to be irrigated as fruit is being produced.

How to grow pineapple guava

Growing pineapple guava from seed is a slow business. It can take a year for seedlings to show any real growth. Most pineapple guava trees are purchased as  1- or 2-year old plants. If you only have room for one specimen, make sure that it is a self-pollinating variety. Most pineapple guavas require a second specimen for pollination. They prefer partial shade, a soil pH of 5.5 to 7.0, and can tolerate some salt spray. They do not respond well to bright, reflected light, so installing pineapple guava next to a driveway probably isn’t the best idea. They can be grown in large containers, and they can also be espaliered or pruned as a small tree, or used to create hedgerows or windbreaks. There are several varieties of pineapple guava to choose from.

Caring for pineapple guava

One of the best things about pineapple guava is how little care they need. You can ignore them completely, once they are established, or you can give them a boost with these maintenance tips:

• water deeply during blossom and fruit set, allowing the soil to dry out between waterings
• mulch around plants
• prune lightly after harvest to increase production next year; also, remove side branches that are less than one foot off the ground
• feed 8-8-8 NPK fertilizer once every two months

Harvesting the fruit

Pineapple guava fruit are egg-shaped and can be 3/4 to 3-1/2 inches long. The fruit is described as tasting like a cross between pineapple, apple, strawberry, guava, and mint. Fruit reaches full maturity (and the best flavor) in fall, but it bruises easily. Ripeness can be determined by giving fruit a gentle squeeze. Harvesting fruit too soon is a waste, since unripe fruit is bitter. Waiting for it to fall on its own usually means bruised fruit. Probably the best solution is to set up a net under the tree to gently capture fruit as it falls, but this isn’t alway feasible. Commercially, ‘touch picking’ is used. Touch picking means that if the fruit breaks free when you touch it, it’s ripe. Regularly checking for ripe fruit before it falls will reduce the number of bruised fruit. Some people eat the entire fruit, skin and all, while others cut it in half and scoop the fruit out with a spoon. 

Pineapple guava no real pest or disease problems. Black scale and fruit flies may show up, but these shrubs are truly trouble-free.

Pineapple guava fruit does not ship well, so most stores never carry it. Adding these trouble-free shrubs to your foodscape means you will have a ready supply of delicious fresh fruit each fall for many years to come.

Plant selection

The trick to attracting and maintaining these beneficial insects is to plan for sequential flowering. Of course, your job will be even easier if you select plants well suited to your microclimate, while you’re at it! The choice of which plants to use depends on the pests commonly found in your garden or landscape. These plants are nearly always a good bet:

Where to put insectary plants

Your insectary plants can be used to create hedgerows that surround a garden plot, along a walkway path, or you can simply intersperse these helpers throughout the landscape. Most residential gardens, however, are too small to make this much of a concern, unlike agricultural fields, so you can put them wherever they will thrive and look nice.

Like other plants in the landscape, your insectary plants will need weeding, irrigation, and protection from vertebrate pests to stay healthy. The initial investment of time and effort will make your job as a gardener that much easier, once these plants become established. Be sure to provide your guests with water, while you're at it!

Sorghum is a global food and fodder crop and it makes a pretty good syrup.

Sorghum is a drought and heat resistant member of the grain family, making it an easy plant in warmer regions. Even if you don't enjoy a bowl of cooked sorghum (and you really should try it), the seeds make excellent food for local birds and wildlife (and backyard chickens). If you’ve ever bought a bag of wild bird seed, the larger, dark brown seeds are sorghum. Sorghum is used predominantly in the South to make syrup, but it is the world’s fifth largest cereal crop. Sorghum’s high sugar content makes it useful in making biofuels, alcoholic beverages, and flour. It can even be popped like popcorn or added to soups and stews, the way you would use barley. Sorghum is an ancient grain, having been domesticated some 8,000 years ago, and it is gluten-free.

Durable sorghum

Cousins to sugarcane, sorghum is one rugged plant. It reproduces by rhizomes and by seeds and it grows and spreads so well that “Johnson grass” (Sorghum halapense) has earned its reputation as a troublesome invasive. The same characteristics that make sorghum a potential problem are the very same characteristics that make it a useful landscape addition. Some sorghum varieties grow as tall as corn, while others have more of a clumping growth. In either case, the wide, flat leaves grow upward and then hang over, staying green all summer. The seed clusters are abundant and prolific. Sorghum is a short-day plant. This means that is needs long nights to begin the flowering process. Most sorghum plan its will die back to clumps in winter and then come back each spring, providing a wealth of seeds for local birds and wildlife (and you!) throughout the summer.

Nitrogen ‘fixing’ sorghum

Like legumes, pineapple, mango, and sweet potatoes, sorghum has evolved alongside a helpful bacteria (Gluconacetobacter diazotrophicus) that fixes atmospheric nitrogen, making it available to the plant and its neighbors (until it goes to seed).

Sorghum pests and diseases

Like many other plants, sorghum has built-in defenses of its own. In its early stages of growth, and when severely stressed, sorghum plants contain relatively high levels of hydrogen cyanide and other chemicals that protect it from being eaten. Dried fruit beetles, sugarcane aphids, crane fly larva, and sorghum midges may also attack your sorghum, but I have found this to be a very durable plant.

Using sorghum in a home garden or landscape

While you can certainly grow sorghum in an agricultural field, this plant also lends itself nicely to the edges of walkway paths, raised beds, difficult areas, and poor soil. Once established, sorghum needs only minimal care and irrigation, compared to most other plants. Also, it will come back, year after year, without any effort on your part.

Try adding this ancient grain to your garden landscape today!