Adventitious roots are different from other roots.

Roots are generally classified as primary or lateral. The primary, or main, root supports a number of side, or lateral roots. Root systems feature either a taproot or fibrous roots. Carrots are an example of a taproot. Fibrous root systems are more “all over the place”. In both cases, the roots are attached to the aboveground portion of the plant at the crown, or to other roots. This is not the case, when it comes to adventitious roots.

Acaulescent is the word used to describe plants with no visible stem. [It is pronounced a-kaw-LE-sent.]

Most plants have one or more central stems that support the aboveground portion of the plant. These plants are called caulescent. Acaulescent plants do not appear to have stems. Instead, these plants tend to grow their leaves close to the ground in a clustered, rosette, or whorled pattern, common of many succulents. Some acaulescent plants can get quite tall, but these are generally still leaves growing out of the ground. Now, don’t be fooled. Acaulescent plants still have a stem, it’s just extremely short and the internodes (the spaces between nodes) are densely contracted.

How acaulescent plants grow

You may be thinking that many succulents have long stems that support flowers, and you would be right. Those inflorescence axis stems are called peduncles. Unlike a trunk or central stem, these growths are purely reproductive and not structural. Many acaulescent plants have modified underground stems, such as rhizomes, bulbs, or tubers. Instead of sending up a central stem, acaulescent plants put leaves out from the crown. Some of these leaves are thick and mucilaginous, as with succulents, while others are the familiar broad leaves of many tropical plants. The stems you do see attaching the leaves to the crown are actually part of the leaf. These leaf stems are called petioles.

Examples of acaulescent plants
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Aloe, agave, and yucca are popular acaulescent plants. Most bulbs, including onion, garlic, chives, and crocus, are acaulescent. The aboveground growths you see in these plants are specialized leaves called scapes. Dandelions, carrots, pineapple, cilantro, lettuce, spinach, and California poppies are also acaulescent. In each case, leaves emerge from a ground level base. Some species of cycad, primrose, oxalis (Oxalis triangularis), and palm (Attalea cuatrecasana) are also acaulescent.

It’s all about ethylene

The lowly ethylene molecule is responsible for many changes within a plant. Ethylene is used by plants in respiration and to inhibit the movement of auxins, a plant growth hormone. By manipulating auxin levels, plants use ethylene to stimulate seed germination and adventitious root growth. It is also used to bend the plant toward the sun (epinasty). This ripening, or aging, hormone also triggers abscission (leaf and ripe fruit drop), chlorophyll destruction, flower drop, and all the signs of senescence (deterioration related to aging).

The physics of ripening

Fruit is food for seeds and seed spreaders. When a fruit falls to the ground, it provides easy access to important nutrients to the seed or seeds contained in that fruit. It also attracts animals that may help the plant disperse its seeds over a wider range. There’s no sense in attracting fruit eaters if the seed isn’t ready. Just as the seed(s) approach maturity, a series of chemical changes take place within a fruit. That’s when ripening kicks in. We all know that, as a fruit ripens, it becomes sweeter and softer. Generally, fruit becomes less green and more colorful as it ripens, too. This is because enzymes are breaking down the chlorophyll. [One study found that birds of different continents prefer different colors of ripe fruit.] This sweetening and softening is the result of certain enzymes breaking starch down into various sugars, such as fructose, glucose, and sucrose. [Any time you see a word ending in -ose, it’s a sugar.]

Some fruits stop ripening as soon as they leave the parent plant, while others continue ripening. Those that continue ripening are called climacteric. Common climacteric fruits include bananas, apples, mangoes, melons, and apricots. These fruits are frequently stored before appearing on grocery store shelves. Non-climacteric fruits, such as grapes, citrus, and strawberries must be harvested when ripe.

People have gone ape over bananas for a very long time - but can you grow your own?

The answer is yes, you can! ​

Native to Indomalaya and Australia, bananas are believed to have been first domesticated in Papua New Guinea around 6,000 years ago.

Bananas are the world’s largest herbaceous flowering plant. Standard banana plants can reach 45 feet in height, but most end up only 16 feet tall. Dwarf varieties can range from 4 to 12 feet in height. According to Guinness World Records, the largest bunch of bananas held 473 bananas and weighed in at 287 pounds!

The banana plant
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Most people refer to the banana plant as a tree, but it isn’t. Bananas plants are perennial herbs that grow from rhizomes. (If you recall, rhizome are underground stems that grow horizontally and herbs, in this case, are non-woody plants.) The fruit, technically, is a berry. The trunk of a banana plant is a false stem, called a pseudostem, made from tightly wrapped leaf sheaths that grow out of a mat or stool, called a genet, that forms a crown.

Each year, from the genet, new shoots will emerge to replace the parent plant, after its fruiting cycle is complete. The first lateral shoots to come through the soil surface are called peepers. As they grow, they are called suckers. There are two types of suckers: water suckers and sword suckers. Water suckers have broad leaves and a small rhizome base. These do not develop into plants strong enough to support a crop. Sword suckers are just the opposite, with a large rhizome and narrow leaves. Newly emerged leaves that are still rolled up are called cigar leaves and they are very fragile. Once foliage leaves are present, they are called maidens. The sucker selected to replace the parent plant each year after fruiting is called the follower or ratoon.

Banana flowers

From the central growth of leaves, a floral stem or aerial true stem, also called the banana heart, emerges with a cluster of female (pistillate) flower. Each of these female flowers develop a seedless berry by parthenocarpy (fruit development without fertilization). These flowers are arranged into two rows that, ultimately, become a bunch, or hand, of bananas. Before that happens, however, those female flowers become longer and skinnier. Then, the far end of each female flower becomes a male flower! These males may or may not produce fertile pollen. Sometimes, in-between the female and male flowers, a third, hermaphroditic, flower emerges. These neutral flowers do not produce pollen or fruit.

Bananas as food

We are all familiar with the edible fruit of a banana, but, the banana flower is also edible in the same way that an artichoke flower is edible, except that they will stain your hands the way a beet can. Traditionally, the hands are rubbed with oil before handling these flowers. You need to remove the tough outer petals to reveal the tender heart. It is actually the bracts that are eaten. Bracts are modified leaves that surround the base of an individual flower. The outer petals look like giant pink Belgian endive leaves and make attractive food containers. Also, the leaves and petals are often used much like corn husks and grape leaves  are used to wrap other foods for cooking.

​Because banana plants grow so quickly and look so nice, some people grow them simply for looks. This means you need to be on the lookout for ornamental varieties when shopping for a banana plant. Ornamental varieties include Ensete ventricosum, Musa ornata, and Musa sikkimensis ‘Red Tiger’. These will never produce fruit.

How to grow a banana plant

Being a tropical plant, bananas prefer heat, humidity, and sun. They generally do not handle wind or compacted soil very well, so be sure to select a site that is sheltered and has good drainage. You can improve a suitable site by digging in some aged compost ahead of time. [I just ordered my own banana plant and will keep you posted on its development.]

Growing bananas in a container

Because banana plants are actually rhizomes, it is easier than you might expect to grow one in a container. You will probably want to grow a dwarf variety. The container needs to be at least 24 inches deep. If you live in USDA Hardiness Zones 9 to 11, you will want to keep your containerized banana in the shade during summer afternoons, and bring it indoors over the winter, while the plant is young.

Harvesting bananas 

Ripe bananas look different to certain animals. Some animals, such as zebra finch and reindeer, are able to see ultraviolet light. When they look at a ripe banana, it glows! If you have one of those handy dandy dollar bill checkers, you can see for yourself: ​

Cation exchange capacity (CEC) is a measure of soil fertility.

The chemistry and science behind how and why a soil’s cation exchange capacity works the way is does is fascinating (and a little too complex for this venue). To put it simply, cation exchange capacity (CEC) is a measurement of how many positively charged minerals can be held by the surface of a soil particle. To learn how this affects the plants in your garden, we will need to touch up on some basic chemistry. Don’t panic - you can do this!

Basic chemistry
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Everything is made up of atoms and molecules that are either positively charged (cations), negatively charged (anions), or neutral. Organic materials and clay tend to be negatively charged. This means these anions attract and hold cations, such as potassium, calcium, and iron, which are important plant nutrients. Many anions, such as phosphorus, sulfur, and boron are held in the water that is found in the spaces between soil particles. Soils with high CEC ratings generally hold onto more water, as well as nutrients. Below, you can see the electrical charge for each plant nutrient.

Soil science

Plant food exists as atoms and molecules of minerals. Minerals make up 45 to 49% of a soil sample. These mineral particles come in a range of sizes, with sand being the largest and clay being the smallest. Here in San Jose, California, we have clay. Chemically, sand is relatively unreactive and neutral. The spaces between particles (macropores and micropores) tend to be large. These spaces, and the lack of an electrical charge, make it more likely that plant nutrients will be leached out, or washed away. This is why sand has a low CEC rating. Clay, on the other hand, is made up of many negatively charged secondary minerals that love to attract and hold cations. Also, the smaller particle size of clay means that it has 100,000 times more surface area than sand, in the same size sample, so there are plenty of places for attachments to occur.

Soil test results

When I had my soil tested, it came back with a CEC rating of 20.6, but what does that mean? A CEC rating of 20.6 is considered relatively high. One way to look at a CEC rating is to think of it as a power strip - just how many cords can be plugged in? CEC is measured using mEq/100g. We won’t get into it, but it basically means how many parts of something there are in a certain volume of soil. Different soil types have very different CEC ratings:

•     Sand                       2 to 6 mEq/100g
•     Sandy loam          3 to 8
•     Loam                      7 to 15
•     Silt loam               10 to 18
•     Clay/clay loam    15 to 30

My soil’s CEC rating of 20.6 means it can hold onto a significant amount of plant nutrients. Another, related figure found on a soil test is called base saturation. Base saturation is the percentage of available connections being used. You will normally see separate figures of base saturation for calcium, magnesium, and potassium. [You can think of them as different sized electrical plugs.] Below, you can see my base saturation results with “values found” (left) and “optimal ranges” (right).

CEC and pH

Soil pH also plays a role in a soil’s ability to hold onto plant nutrients. This is because pH is a function of rogue hydrogen cations (H+) floating around in the soil. Soils with a higher, more alkaline pH, tend to have a higher CEC rating. Of course, too much of a good thing turns out to be a bad thing. If the soil becomes too alkaline, nothing can grow in it! This is true in other ways, as well. Too much ammonium (NH4+) in the soil can interfere with the uptake of potassium (K+), calcium (Ca2+), and magnesium (Mg2+). This is why soil tests are so important. Armed with the information they provide, you can look at fertilizer labels with a more informed idea of what your soil actually needs. Acidifying our local clay is one way to make more nutrients available to your plants. The opposite is true in areas with acidic soil. There is a happy medium, but soils with a higher CEC rating are more difficult to alter, when it comes to pH.

At exactly 8:28 AM, on December 21, 2017, the northern hemisphere of planet Earth was tilted as far away from our sun as it gets. [The Earth is actually as close to the sun as it gets between the 3rd and 5th of January, but we are tipped away, so we don’t notice.] So, how is your garden affected by winter solstice?

What is winter solstice?

Before we learn how shortening and lengthening days affect your garden and landscape plants, let’s take a moment to discuss what, exactly, is meant by winter solstice. The word solstice comes to us from the Latin words for sun (sol) and “to stand still” (sistere). Obviously, the sun and earth never really stop moving. It’s an illusion that refers to the two extremes of the Earth’s travels around the sun.

​We all know that the Earth has an equator around the middle and poles at either end, except those ends are not exactly up and down. The Earth is tilted 23.5° (23.44°, if you want to be really accurate). This means, for half of each trip around the sun, the northern hemisphere is closer to the sun, while the southern hemisphere is closer the other half of the year. You can see it easily if you hold one hand up at an angle and the other up as a fist. Your fist is the sun. Move the slanted, open hand around your fist, keeping the angle pointing in the same direction the whole time. Moving from one side to the other, you will see that different parts of your open hand are closer to your fist. When either hemisphere is at the farthest point from the sun, we call it the winter solstice. Six months later, when we are as close as we will get, we call it summer solstice. So what does this have to do with gardening?

Did you know that you can grow your own quinoa?

Just don’t do what I did, which was to start it as summer temperatures were reaching 100°F! Let’s learn more about this high protein, ancient grain, so that you can add it to your foodscape.

What is quinoa?
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Quinoa (Chenopodium quinoa) is a member of the amaranth family, along with beets and spinach. Quinoa is grown for its high protein seeds. Unlike most cereal grains, quinoa is not a grass plant, so its seeds are classified as a pseudocereal. People started farming quinoa 4,000 years ago in the Peruvian Andes, but it has been a food staple for as long as 7,000 years. One of the things that makes quinoa so special is that it contains all eight essential amino acids used by our bodies to make a complete protein molecule, plus it is gluten-free, for those suffering celiac disease.

The quinoa plant

Quinoa is a self-pollinating dicot, which means its seeds split in half and its flowers have petals that are in multiples of four or five. Unlike many other plants, quinoa flowers are green. Quinoa plants have deep taproots that make them drought resistant. Its leaves are broad, with tiny hairs (trichomes), and lobed. Plants can grow from 18 inches tall to over six feet. The central stem may be green, purple, or red, depending on the variety. Quinoa seeds can be black, tan, white, pink, red, or purple, depending on the cultivar. All quinoa seeds are coated with saponins, which taste bitter. This protects developing seeds from birds and other seed eaters, but the coating needs to be rinsed off before cooking and eating your quinoa. [In parts of Africa, those saponins are collected and used as a laundry detergent!] While young quinoa leaves are edible, they do contain high levels of oxalic acid, which can cause respiratory and kidney problems. But you’d have to eat an awful lot of quinoa leaves to have a problem.

How to grow quinoa

Quinoa plants are pretty rugged. They can be grown from sea level all the way up to the highest mountain tops (13,000 ft.), just give them plenty of sunlight. You will want to select a variety that is suited to your microclimate and elevation. Quinoa grows best in loose, sandy soil. If that's not what you have, you can either grow your quinoa in a raised bed, or you can incorporate a lot of aged compost into your quinoa bed before planting. This will provide nutrients and improve drainage. Do not try growing quinoa in containers - it needs more underground space than a container can provide. Quinoa prefers a soil pH of 6.0 to 8.5, so our alkaline soil isn’t a problem. Seeds should be planted 1/4 of an inch deep and watered very gently, to avoid washing seeds away before they get a chance to germinate.

Quinoa plants prefer temperatures from 25°F to 95°F. This means you can start growing your quinoa in autumn. That way, your plants will be harvested long before the summer heat kicks in! Quinoa plants take 90 to 120 days to mature, so plant accordingly. Freezing temperatures will sterilize quinoa pollen, so frost that occurs during flowering can be problematic. These plants grow very slowly during their first two or three weeks, so snipping off weeds at ground level is the best way to reduce competition without disturbing the soil. Depending on the variety, plants only need 10 to 39 inches of water during the growing season. Quinoa plants should not be watered once they start going to seed.

Quinoa pests and diseases

While quinoa seeds protect themselves with saponins, many birds will still feast on your crop. You can use netting to reduce losses. Other pests include flea beetles, caterpillars, aphids, armyworms, and the recently discovered quinoa plant bug (Melanotrichus sp.). Bacillus thuringiensis can be used to control caterpillars. According to a report from Perdue University, there are no pesticides cleared for use on quinoa. Quinoa is prone to several fungal diseases, which is why good drainage is so important. Damping off disease, downy mildews, fusarium wilt, seed rot, leaf spot, and brown stalk rot can all affect your quinoa plants.

There are spring and winter varieties of barley, depending on whether or not they need a period of cold to transition into their reproductive phase. In warmer regions, that generally means planting in either October or January. Barley’s reproductive phase is characterized by true stems, called culms, carrying flowering heads, also known as a spikes or ears,  that emerge from the sheath, or boot. surrounding the uppermost leaf (called the flag leaf). Barley grows 2-1/2 to 3 feet tall.

Barley hulls

Barley seeds have tough coverings called hulls. Most varieties have hulls that are difficult to remove without losing or damaging some of the grain. These are also known as ‘covered’ barley. The barley you see in the store is usually hulled or pearled barley. Hulled barley is a whole grain, but pearled barley is not. Pearling removes several outer layers of the grain along with the hull. There are also hulless, or ‘naked’ barley varieties, but they aren’t really hulless. Instead, the hull is simply easier to separate from the grain. Barley hulls are often used to make pillows.

Why grow barley?

You may want to grow a small patch of barley, simply as a testament to our agricultural history, to know that you can. You may want to try making your own beer or whiskey. You may want to grow more of your own ingredients for a hearty winter soup. Barley can also be grown as a cover crop or green manure, to reduce erosion, improve soil structure, and suppress weeds. Barley is an excellent crop to install as your winter fava beans start ending their growing season. If you add a legume, such as peas or beans, and leave the plants in place, you can significantly improve nutrient cycling. Barley grown in winter has a deep, fibrous root system that can go down over 6 feet! Also, because barley grows so quickly, it absorbs surface water that would otherwise be used by weeds. Barley plants also shade out weeds and the plants emit allelopathic chemicals that suppress weed growth. Barley can also be used as a nurse crop. Nurse crops provide protection for slowing growing crops, such as beets.

How to grow barley

Barley seeds are planted using a method called drilling. Drilling is exactly what it sounds like: you drill a hole in the ground and drop a seed in. Commercial growers have heavy equipment that drills and plants seeds automatically. You probably don’t have one of those machines in your garage, so you will have to do it by hand. Barley seeds are planted deeply. By deeply, I mean 2 inches deep. When I first started growing things in my California concrete soil, I actually used a battery powered drill to plant seeds. After five years of composting, mulching, and top dressing, the drill is no longer needed. Now, I use a hand weeding tool to poke a hole in the ground.

Barley does not like waterlogged soils, so allow the soil to dry out between waterings. Of course, if it’s a rainy winter, there isn’t anything you can do about it other than continuing to add organic material to the soil, to improve drainage. You can see a spreadsheet of various barley cultivars suitable for growing at home here.

Barley pests and diseases

As a cereal grain, barley is prone to fungal diseases, such as leaf scald, net blotch, stripe rust, leaf spot, and stem rust. Common pests include mites, armyworms, grasshoppers, crane flies, stinkbugs, wireworms, and aphids. Also, aphids may carry a viral disease called barley yellow dwarf. Some people claim that barley acts as a natural pesticide, but research has not shown this to be true.

Flowering plants

Flowers are the reproductive organs of an entire group of plants called angiosperms. Angiosperms are the largest group of plants on Earth and they make up a huge portion of our food supply. Angiosperms use flowers to create seeds that are covered by a protective, often edible, outer covering. The fruit that we eat is nearly always the ovary of a flower. This includes cucumbers, melons, apples, peaches, avocados,  squash, tomatoes, eggplants, and, well, really, the list is too long to include here, but you get the idea.

So, what makes a flower a flower?

Flower structure

Some flowers are male, some flowers are female, and some flowers are both, though not always at the same time. Flower parts are either vegetative or reproductive. These parts are generally arranged in a whorl around a central stem. If a flower has parts (petals, stamens, or other parts) that are divisible by three, it is probably a monocot. If it has flower parts that are divisible by four or five, it has been, most likely, classified as a dicot. That classification system has recently gone through some changes, due to genetic research. Many dicots are now classified as eudicots.

Looking at the base of a flower, you will see the vegetative perianth. The perianth is the outer part of a flower, made up of the green sepals (calyx) and colorful petals (corolla). The reproductive parts of a flower are divided by gender. The Greeks called them gynoecium (woman’s house) and androecium (man’s house).

      Woman’s house The female aspect of a flower is called the pistil. The pistil has three parts: the stigma, style, and ovary. The stigma has a sticky tip, which is where pollen is received. The style is a long, tubelike structure that leads to the ovary. The ovary contains egg cells called ovules. Some scientists call the pistil a carpel. I don’t know why.

      Man’s house The male aspect of a flower is called the stamen. Stamens are pollen producing anthers held on top of filaments.

Floral attachments and arrangements

Most flowers grow at the end of a long stem, called a peduncle. When a single flower is made up of many tiny flowers, it is called an inflorescence, and the individual flower stems are called pedicels. Sunflowers and daisies are examples of inflorescence. Some flowers may be directly attached to the parent plant, with a very small or absent stalk. These flowers are called sessile. Crocus flowers are sessile. The place where stem meets flower is called the torus or receptacle.

Flower symmetry

Flowers are classified according to their symmetry. If you cut a flower in half, down the middle, you will either have a ‘regular’ (actinomorphic) flower, or an ‘irregular’ (zygomorphic) flower. Regular flowers will have identical halves, no matter how they are bisected. Roses are regular flowers. Irregular flowers will only look symmetrical along one cut. Orchids and snapdragons have irregular flowers. Regardless of their symmetry, flowers are all about reproduction and sharing genetic information through seed production. Sometimes, they even help with dispersal.

Seed dispersal

Some flowers have structures that aid in seed or spore dispersal. These structures are called diaspores, and you have already seen them. They are the helicopters (samara) of maple trees, the flying seeds (achenes) of dandelions, and the spikelets of foxtail grasses. Tumbleweeds are giant diaspores.

Edible flowers

As much as we love to eat the fruit of a flower’s labor, sometimes the flower itself is edible. Borage, nasturtiums, chive, basil, squash, dill, and cilantro flowers are all edible and they make nice colorful additions to salads. Of course, if you eat a squash flower, you won’t get the squash fruit. Also, not all flowers are edible. Some flowers can make you very sick, or worse. Always check before eating something new, and give it a rinse. There may be chemicals, pollutants, bug poop, or live insects hidden in a flower’s nooks and crannies. Also, some edibles flowers, such as dandelion, taste fine when young, but can get bitter as they mature. 

Flower pests and diseases

Flowers are susceptible to certain pests and diseases. Common flower pests include citrus bud mites, budworms, voles, thrips, Eriophyid mites, and, of course, aphids. Diseases that specifically attack flowers and buds are petal blight, aster yellows, gray mold (Botrytis), phytoplasmas, olive knot (Pseudomonas spp.), and blossom blight (brown rot).

Bolting
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When a plant suddenly sends up a central stalk and flowers, it is called bolting. Bolting usually occurs in response to extreme heat or drought. You could say that it is a panic response to harsh conditions, but it is also a normal part of many plants' natural life cycle.. Rhubarb, lettuce, spinach, bok choy, and other cool season crops will often bolt if grown in the summer. Once a plant starts to bolt, much of the flavor is lost.

Bronzing your baby's shoes is one thing; bronzing in the garden indicates a problem.

What is bronzing?

Bronzing refers to how some leaves or fruit turn purplish or bronze-colored due to mineral imbalances, pest feeding, chemicals, environmental conditions, or disease. Bronzed leaves are often smaller, and damaged areas cannot perform photosynthesis. Bronzing damage may look similar to sunburn damage, except that sunburned leaves tend to turn gray rather than bronze. Bronzed fruit has a dry, rough texture.

Mineral imbalances
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Too much or too little of certain minerals can cause bronzing. Regularly adding organic material to your garden soil helps minimize mineral imbalances. But it’s still a good idea to know what to look for when scouting your foodscape:

• Chlorine deficiency – More likely in sandy soils, symptoms include bronzing, stunting, necrosis, chlorosis, and wilting.
  
• Copper deficiency – Copper deficiencies are rare. When they occur, they make trees look more like shrubs than trees. Bronzing, shoot, twig and needle dieback, and witches’ broom are common symptoms.
  
• Iron toxicity – Iron toxicity often appears as bronzing and reddish spots. These symptoms are from iron oxidizing the chlorophyll used in photosynthesis. In areas with heavy clay soil, insufficient iron is more likely.
  
• Manganese deficiency – Manganese is an immobile nutrient, so deficiencies are seen in younger leaves first. Manganese deficiencies look very similar to iron (Fe), magnesium (Mg), and nitrogen (N) deficiencies, with interveinal chlorosis and bronzing. Brown specks may also be visible.
  
• Sodium toxicity – Too much sodium can cause severe chlorosis, bronzing, and leaf drop. Stunting and other water stress symptoms are also common.
  
• Zinc deficiency – Rare in most areas, zinc deficiencies appear as twig dieback (necrosis), yellowing (chlorosis), and leaf bronzing, often caused by too much phosphorus in the soil. Zinc deficiencies are more common in container plants.

[Did you know that rice farmers rate their plant varieties using leaf bronzing scores (LBS)? They rank rice varieties according to their ability to tolerate excessive iron in the soil.]

Pest feeding

As pests feed, leaf and fruit bronzing may occur. Most of these pests are sap-suckers:

• Mites can cause leaf stippling and bronzing. Fruit can also take on a russet, bronzed appearance.
• Nematode feeding may cause bronzing and stunted growth of boxwood.
• Thrips may cause bronzing and downward leaf curling of lettuce, strawberries, blueberries, boxwood, and many other plants.
• Aphids, scale insects, and whiteflies may also cause bronzing.

Chemical damage

Damage can occur when herbicides, pesticides, and fungicides are incorrectly applied. Also, the wind can carry herbicides and other chemicals from neighboring gardens and yards that may cause leaf bronzing. Bronzing, necrosis, interveinal chlorosis, desiccation, and distorted growth may indicate chemical misuse or overspray.

Environmental conditions

Air pollution often causes high ozone (O3) levels in the atmosphere. Ozone, combined with high temperatures and bright sunlight, can cause purple-brown discoloration, or bronzing, on the upper surface of leaves. Bean plants are especially vulnerable to air pollution.

Disease

Many plant diseases include bronzing as a symptom. These include spotted tomato wilt (carried by thrips), phomopsis stem canker in sunflowers, alfalfa mosaic, cotton root rot, and blueberry bronze leaf curl.

Use bronzing as a clue when you walk through your garden. The brownish or purplish discoloration of bronzing is a clear sign that something is amiss.

​Groundcherries (Physalis) get their Latin name from the papery bladder that surrounds the fruit. This bladder is made from the calyx. [The calyx is the green sepals that form around the base of a flower.] The common name refers to the way fruits are harvested, once they fall to the ground. There are over 75 species, all of which are native to the tropical Americas, including tomatillo (P. philadelphica). There are both edible and inedible members of Physalis. Inedible ground cherries are considered weeds.

Groundcherry plants

Groundcherry plants look very much like tomato plants, but the stems are sturdier. The leaves can be oval, triangular, or lance-shaped. Like other nightshade plants, the bell-shaped flowers have five petals, with yellow, green, white, or purple centers. These bushy plants are often grown as annuals, but can be perennial, under the right conditions. The fruit is the size of a cherry and can be orange, green, yellow, or purple, with a structure much like tomatoes.

Groundcherry weeds

​Chinese lantern (Physalis alkekengi) is an ornamental, inedible groundcherry that can become invasive. There is some talk about certain groundcherry species being toxic, but research has not consistently shown this to be true. More research is being done, mostly because there is a lot of debate about the different groundcherry species.

How to grow groundcherries

If you can grow tomatoes, you can grow groundcherries. These plants like a lot of sunshine and hot temperatures, which makes them well suited to the South Bay Area. Also, it performs well in poor soil and can be grown in containers. Start seeds in small pots 6 to 8 weeks before the last frost date, planting them 1/4 inch deep. Keep the soil moist. Seeds should germinate in 7 to 10 days. Like tomatoes, groundcherries will sprout roots from their stems, so seedlings should be planted deep enough to bury the first or second stems, after plants have been hardened off. This will give your groundcherry plants a better root system. These plants get bushy, like tomatoes, so be sure to give each plant the room it is going to need.  Plants should be at least two feet apart. Irrigate regularly and be sure to top dress around the plants with aged compost. Groundcherries are heavy feeders.

Groundcherry pests and diseases

Like their cousin, the tomato, groundcherries are susceptible to aphids, spider mites, whiteflies,  hornworms, cabbage loopers, flea beetles, nematodes, cutworms, stinkbugs, and slugs. Many of these pests can be thwarted with row covers. Groundcherries are resistant to many diseases, but they may be affected by verticillium wilt, fusarium wilt, curly top, tobacco mosaic virus, and alternaria.

The carbon to nitrogen ratio (C:N) describes relative proportions of carbon and nitrogen in a substance. That substance can be soil, compost, or plants.

Carbon is used as energy and a building material, much the way carbohydrates and sugars are used by us. Nitrogen is needed by to generate proteins, amino acids, and enzymes, making it the steak and salad portion of a garden diet. The energy contained in carbon can only be used if there is enough good health provided by the nitrogen.

With the proper C:N ratio, plants can thrive, soil can support plant growth, and compost can decompose quickly. Improper C:N ratios can interfere with the soil microorganisms that make everything else in the garden possible.

Soil microorganisms

Soil microorganisms are responsible for the decomposition of dead plant and animal matter. They also break down minerals and chemicals found in the soil, turning them into plant food. Soil microorganisms prefer a C:N ratio of 24:1. This means they perform best in an environment that is 24 parts carbon and 1 part nitrogen. Since some carbons break down more slowly than others, the Golden Rule of C:N ratios is 30:1.

Microorganisms have a C:N ratio of 8:1. When they consume carbon and nitrogen, 16 parts of the carbon is burned off as energy, while 8 parts are used for maintenance. If higher levels of carbon are available, such as right after applying straw as a mulch, the microorganisms will pull nitrogen from the soil to maintain the balance they need. This means there will be less nitrogen in the soil for your plants. This tying up of nitrogen is called immobilization because the nitrogen is unavailable until the microorganisms die and decompose. The latter half of this cycle is called mineralization, because minerals are returned to the soil. Materials added to the soil with a C:N ratio of less than 24:1 means there will be an abundance of nitrogen left over for your plants. 

What’s your soil’s C:N ratio?

Complex lab tests are used to calculate C:N ratios for commercial agriculture. Since nitrogen doesn’t stick around for very long, you don’t need to go to the trouble or expense for an actual test. Instead, you can manipulate the C:N ratio with cover crops, crop rotation, mulch, and composting, If you have the correct C:N ratio, your plants will be able to eat and your compost will break down quickly, If the C:N ratio is out of whack, things won't be running as smoothly.

Cover crops and C:N ratios

Many cover crops, such as fava beans and other legumes, are grown to both protect the soil from erosion and compaction, and to add nutrients to the soil. You need to find a balance point between allowing the cover crop to grow, when to cut it, and what to replace it with as it decomposes in place. Cover crops are an excellent way to protect and feed the soil between regular crops. Depending on the plants used as a cover crop, you can ensure that your soil microorganisms and your plants have the nutrients they need.

If you ever get the chance to grow your own turmeric, you really ought to give it a try.

​It makes a lovely houseplant, as well as a nice addition to your spice collection.

How to grow turmeric

If you take a close look at one turmeric rhizome, you will see little nubs. Those nubs are buds. You can break a larger chunk into smaller pieces, just make sure each chunk has 2 or 3 buds. For each chunk of root, fill a medium sized container with rich, loose organic soil and place the root 2 inches below the surface with the buds pointed up. [If a nub has two buds, pointing in opposite directions, lay it down so that the buds point to either side and let nature do the rest.] Water it well, the first time, making sure the container drains properly. After that, water only when the top inch or so of soil has dried. Your turmeric plant will take 7 to 10 months to reach a harvestable size.

Harvesting turmeric
​
Harvesting turmeric is a lot like harvesting potatoes. You really can do it at any time. The longer you wait, the bigger the bounty. Gently dig your fingers down into the soil, near the stem, and feel for the rhizomes. If they feel large enough, wriggle them loose and pull them up. Then, just take what you need and put the rest back in the soil for the next harvest!

The rhizomes can be boiled and eaten like any other root vegetable. The leaves are often used as food wrappers for steaming, the same way corn husks are used to hold tamales.

Add some turmeric to your windowsill garden today!

Secondary plant nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). 

The nutrients plants use the most are called primary nutrients. Nitrogen, potassium, and phosphorus are primary nutrients. On the other hand, only tiny amounts of boron, copper, iron, chloride, manganese, molybdenum, and zinc are needed. These micronutrients used to be called trace elements. In the middle are the secondary nutrients. Secondary nutrients rarely need to be supplemented, but they are very important to plant health.

Most soils already contain high enough levels of these secondary nutrients, but you don’t know for sure without a lab-based soil test. The effects of not enough or too much of any one nutrient can create a domino effect that is difficult to diagnose. Simply adding more fertilizer can often makes problems worse, rather than better.

Why are these secondary nutrients important and what are some signs of toxicity or deficiency? Let’s find out!

Calcium

Plants use calcium to build strong cell walls, to move materials across cell membranes, to grow primary root systems, and to maintain the cation-anion balance. [Cations and anions are electrically charged atoms of minerals that plants use for food.] Optimal levels of calcium range from 1000 to 1500 parts per million (ppm).

Calcium is relatively immobile inside a plant. It takes a lot of water to move a calcium molecule around inside a plant. That’s why blossom end rot is more of an irrigation problem than a calcium deficiency problem. Calcium deficiencies, whether caused by real lack or insufficient irrigation, are rare in nature. When they do occur, they can cause bitter pit in apples, cavity spot in carrots, and leaf tip burn in several different plants.

Too much calcium is also rare, but it can interfere with the absorption of magnesium and potassium, causing deficiencies in those nutrients. Bottom line with calcium: irrigate adequately, regularly and consistently.

Magnesium

Magnesium is essential for plant health. Ideal levels of magnesium range from 50 to 120 ppm. Magnesium stabilizes cell membranes, making plants better able to withstand drought and sunburn. Magnesium is found in enzymes that plants use to metabolize carbohydrates. Most important, magnesium is contained in the chlorophyll molecules that convert the sun’s energy into food. This process, the Calvin Cycle, is what makes photosynthesis possible. 

Too much magnesium in the soil makes it difficult for plants to absorb calcium and other nutrients, which can lead to blossom end rot, bronzing, and many other problems. This is a common problem in areas with alkaline soil. The opposite is true in areas with acidic soil. 

Insufficient magnesium symptoms look like potassium toxicity symptoms. Older leaves, at the bottom of the plant, start turning brown, between and alongside the leaf veins, working upward through the plant. Magnesium deficiencies in stone fruits often start out as slightly brown areas along leaf edges (margins) that expand inward, causing cracking, necrosis, and leaf loss. Magnesium deficiency in California is extremely rare.

Sulfur

Plants use a surprising amount of sulfur. This secondary nutrient is used in making chlorophyll and certain proteins and enzymes. Sulfur is also part of the arrangement between legumes and rhizobia bacteria that allow them to make use of atmospheric nitrogen.

Sulfur deficiency is seen first in new growth. Leaves are pale and growth is spindly. If sulfur levels become toxic, leaves will be smaller than normal and have scorched edges. Sulfur is commonly used as an organic fungicide and to acidify the soil.

Do not use horticultural oil within 2-4 weeks of applying sulfur. Sulfur and horticultural oil are phytotoxic (poisonous to plants) when combined. Also, it is better to use fixed copper, rather than sulfur, on apricot trees.

Your plants may not need as much of these secondary nutrients, but they are just as important to plant health. Get a lab-based soil test to find out what is in your soil.

Cavity spot is not your worst prison nightmare. Instead, it is a fungal disease of carrots.

Cavity spot appears as depressed lesions on mature carrot taproots. These lessons can be elliptical or irregular in shape. They start out as sunken pinpoints that grow larger as the root grows. Lesions are usually less than 1/2 inch across but can get bigger. These lesions are commonly seen on the top one-third of the carrot, near where lateral roots emerge.

This fungal disease is caused by Pythium sulcatum and P. violae spores found in the soil. These spores become active in cool, wet weather, which happens to be when your carrots are growing. Cavity spots occur most often when soil temperatures are near 58°F.

In addition to carrots, cavity spot occurs on alfalfa, beets, black-eyed peas, celery, cucumber, wheat, and several weeds.

Controlling cavity spot

Harvesting carrots as soon as they are mature will reduce the likelihood of infection. And avoid over-watering. Too much moisture in the soil encourages several different fungal growths. A three-year crop rotation is the best way to prevent this disease or to interrupt the disease triangle in your garden.

So, protect your carrot crop with good cultural practices and just the right amount of irrigation.

Beneficial winds

Seedling development is a function of sunlight, moisture, temperature, and wind. Being blown around stimulates the stem to be stronger. Botanists call this action thigmomorphogenesis. Plants grown in greenhouses, without any wind, are gently knocked around by a machine that helps prevent the plants from becoming too tall and spindly.

Note: While most pollen is too sticky to be affected by wind, wind is the primary mechanism for pollination of corn plants.

Wind damage

Wind dries plants out. Plants exposed to a lot of wind need more water than their protected brethren. Wind can also speed up erosion. Ground covers and mulch reduce that erosion. During heavy winds, you may want to move containerized plants next to a fence or wall to prevent breakage. 

Protect tall plants against wind damage with stakes, tree supports, and tomato cages. Wind damage can be in the form of branches flailing around and tearing holes in leaves and branches rubbing together. Wind damage provides pathogens with a way in. And hot summer winds can lead to blossom drop and fruit set failure.

Wind wounds

Strong winds can rip heavily laden branches or overly large limbs from a tree, leaving jagged wounds. You can help these trees recover quickly by cutting the tear to make it a flat surface, close to the trunk, but not too close. Do not cut into the branch collar. And you do not need to paint the wound. Instead, allow the tree to protect itself. It will grow a callus over the area. You may, later on, need to provide the callus with sunburn protection.

Diseases on the breezes

Disease-causing pathogens are usually microscopic. As such, they can catch a free ride on every breeze that blows through. [I wonder if that would make it a case of phoresy…] In any case, several diseases can arrive in your garden in the wind. Gray mold (Botrytis cinerea) is always present. That is why rotting fruit gets that gray fuzz so quickly. It’s everywhere. 

Mummy berry spores blow into your garden on the wind. So do chemical oversprays. The chances of ringspot on Brussels sprout skyrockets after a windy day, and citrus blast often occurs right after periods of wind-driven rain. You can reduce the likelihood of citrus blast by providing citrus trees with some wind protection.

Wind protection

Wind protection can take many forms. It may be a fence, a hedge, or a row cover.. You can protect plants from wind by installing them close to your house. Pineapple guava, mature blueberry bushes, and many fruit and nut trees can provide a windbreak. Portable cold frames can protect smaller plants against cold winter winds. 

When spring comes around, wind can mess up a plant trying to get established in a new location (ecesis). The wind is one of the main reasons for taking the time to harden off plants started in protected areas. And when you start planting those tiny seeds, such as lettuce, you can often lose most of your crop to the wind. They simply blow away. [You may want to check your neighbor’s yard for all that lettuce and endive you planted last year…] And all those delicate seedlings that emerge can be protected from the wind with a moistened layer of vermiculite. Or, you can cover them with a plastic gallon jug (cloche) with the bottom cut out. Just be sure to bury the edges or weigh down the jug enough to prevent it from blowing away, too!

Stems - they hold flowers up, leaves on, and don’t seem particularly interesting, but they are!

The word stem can refer to the trunk of a tree (aborescent), a bramble cane, a stalk, or a bine. [Bines are the stems of climbing plants, such as hops, that wrap themselves around external supports without the use of tendrils.]

Stem basics

Stems are the main aboveground stalk of a plant or shrub. [The roots are the below ground portion.] Stems can also be a limb that holds fruit, flowers, or leaves onto a larger limb. Stems perform four functions:

• stems provide structural support and they support leaves, flowers, and fruit
• stems hold the vascular bundle that carries water and nutrients between the roots and shoots
• stems store nutrients
• stems produce new plant tissue (meristems)

Stem structure

On the outside, stems are usually divided into nodes and internodes. Nodes are areas that hold leaves. Nodes are also where buds, petioles, and even roots can emerge. Internodes refer to the distance between nodes. These two pieces of information can often help in plant identification.

​On the inside, stems have three basic tissues: the outer skin, or dermal layer, ground tissue, and vascular tissue. You may already know that vascular tissue consists of the xylem and the phloem. Ground tissue, or parenchyma, is the “everything else” of plant soft tissue. There is no ground tissue in woody stems. Stems of annuals are usually herbaceous, which means green and flexible. Since they lack a cambium layer, they do not tend to get very big around. Woody perennials have a tough outer layer that gets wider each year.

Dicots, eudicots, monocots, and gymnosperms 

Most plants used to be classified as monocots (grasses), dicots (beans), or gymnosperms (pine trees). Recent genetic research has taught us that dicots are better described as a new new group, called eudicots. These different plant classifications have unique stem structures, when seen in cross section. Eudicot stems contain pith. Pith is the spongy material you see inside a sunflower stem. They also contain bast fibers. Bast fibers are what we harvest to make linen from the flax plant, and they protect the phloem. Vascular bundles form a ring near the outer edge of the stem. Monocot stems have vascular bundles scattered throughout the stem. Gymnosperms are similar to eudicots, except they use tracheids as part of their vascular system.

​Stem variety

Most stems are pretty obvious, and some, like the sunflower, can be substantial. That is, of course, until you consider that a redwood tree trunk is also a stem; A monumental stem, weighing in at 50,000 pounds! The stems that hold up flowers are called peduncles. In flower clusters, or inflorescences, the stems are pedicels. Sometimes, plants have stems so short that it looks like the leaves grow right out of the ground - these are called acaulescent stems.

Buds on twigs are also stems. Bulbs and corms are underground stems and leaves, but bulbs are more leaf than stem. Rhizomes are underground stems of many grasses, iris, and most ferns. [Most ferns don’t actually have an upright stem; instead, they have semi-rigid rhizomes.] Strawberry ‘runners’ are stolons, which are also stems. Potato plants also have stolons. Some stems grow in a tangled mess, or in low growing mats. This is called caespitose. Hostas, garlic, lilies, and iris have stems called scapes. Cacti and succulents have specialized leaves for holding a lot of water. Many of the “leaves” you see on these plants are actually flattened stems, called cladodes, that can perform photosynthesis.

Stems in the garden

Those melon and squash plants, the ones that send stems out along the ground, are called decumbent. You can remember that would because “dey come, bent up at de end.” [Hey, if it helps, why not?] Your shrubs have stems that are called fruticose.

Flower stems

As you have probably noticed, some flowers and fruit, such as sunflowers and raspberries, respectively, are actually made up of dozens, or hundreds of tiny florets. The single stem that holds up a sunflower head is called a peduncle, while each of the tiny stems that hold clusters of minuscule blooms are called pedicels. The thorns on your rose bush and the prickles on your blackberries are actually modified stems. So are tendrils. [Technically, rose thorns are not thorns at all. They are prickles, but I don't think we're going to change anyone's mind about that today.]

Food from stems

We get a large portion of our food from stems. Some may be familiar, but others may surprise you:

• asparagus
• bamboo shoots
• chicle, used to make chewing gum
• cinnamon, from tree bark
• gum arabic, a food additive
• kohlrabi
• maple sugar from maple tree sap
• nopalitos (cactus pads)
• sugar, from sugar cane
• water chestnuts

We also get things like camphor, quinine, and lumber (and all it’s related products) from the stems of plants. Many people assume that celery is a stem, but it isn’t. Celery is the stem that supports a leaf, making it a petiole, or leaf stalk. The stem of a celery plant is actually the round stubby base.

Stem pests and diseases

Stems are usually pretty well protected, but that isn’t always enough. Young stems infected with damping off disease are usually doomed from the start. Crown gall can cause lesions on stems. Other diseases that can appear on stems include peach leaf curl, blackleg, mummy berry, stem blight, anthracnose, Phytophthora tentaculata, black spot, and bacterial speck. Bagrada bugs, cutworms, eriophyid mites, katydids, crickets and grasshoppers, weevils, and harlequin bugs will feed on stems. Also, many pests use stems as hideouts and egg laying territory, so keep your eyes open!

Peaches may be the last thing on your mind right now, but autumn is a good time of year to find room on your property for a peach tree. Even if you don’t have room in your yard, dwarf peach varieties can be grown in containers.

Peach trees make a lovely addition to a foodscape. Fragrant spring blossoms give way to fruit that practically defines summer. Autumn leaf drop makes pruning easy and what winter would be complete without a surprise dessert of peach cobbler? A mature peach tree can produce up to 65 pounds of fruit each year. That’s over 200 peaches!

History of the peach

Did you know that peach trees have been around for over 2.6 million years? Traditionally thought to be from Persia, genetic research shows that peaches actually originated in China. Also, it was thought that peach cultivation started some 6,000 years ago, until some ancient writings showed that certain kings and emperors, back in the 10th century B.C., favored a delectable peach now and then. So, if you love peaches, you are in good company.

The peach tree

Peaches and nectarines are the same fruit, like fraternal twins. The only difference is that peaches have fuzzy skin (trichomes) and nectarines are smooth skinned. This difference is due to a recessive gene, the same way blue eyes or red hair occurs. Peaches are in the rose family, members of the Prunus genus, all of which produce fruits called drupes. This makes them cousin to almonds, apricots, cherries, and plums. Peach trees are in a group of plants that use specialized cells for storage, manufacturing, and as weapons. These cells are called idioblasts.

Standard peach trees can grow 25 to 33 feet tall and 25 feet wide, if you let them. For the best productivity and tree health, it is better to keep them pruned to 15 feet by 15 feet. Dwarfs can reach 8 to 10 feet. Most peach trees in Maine only live 7 years, while California peach trees live 12 to 20 years.

Peach trees and chill hours

Before you plant a peach tree, you need to understand chill hours. Each winter, peach trees enter a period of dormancy. Being deciduous, they lose all their leaves and enter a winter rest. During that rest, the number of hours spent between 32°F and 45°F are accumulated (don’t ask me how - I have no idea). These “chill hours” must reach a certain number for a tree to be able to blossom properly in the spring. Once enough chill hours are accumulated, the tree enters a different type of dormancy called quiescence. Depending on the variety, peach trees need 600 to 900 chill hours. Here in the Bay Area, we generally only get 450 chill hours. When selecting a peach tree variety, you want to take chill hours into account. There are several models used to calculate chill hours, and each one gives you different information. Below you can see the chill hour results for the South Bay Area. Go to my page on chilling hours to learn how to get your local information. There are hundreds of varieties to choose from. According to UC Davis, using the Dynamic Model, the following varieties have their chill hours noted alongside:

[Using the Dynamic Model, San Jose receives an average of 52 chill portions each year, so only two varieties would be a good choice.] You can see detailed list of different fruit trees at the UC Davis Home Orchard.

Peach varieties

Peach varieties are divided between cling and freestone. Those names refer to how easily the fruit comes away from the pit. Freestone peaches tend to have firmer fruit, while clingstone peaches are known for their sweeter taste. Clingstone varieties are harvested May through August, while the freestone harvest extends into October. There is also a hybrid cross between the two, called a semi-freestone, and flat varieties, called pan-tao. Not all peach tree varieties perform well in all regions or microclimates. Check with your local County Extension Office and be sure to verify your growing zone using the USDA Hardiness Zone Map.

Growing a tree from a peach pit

While you can eat a peach and then plant its seed, this doesn’t always work out the way you expect. Like apples and many other fruits, peach seeds do not necessarily produce offspring that taste as good or grow as well as the stock you buy at your local nursery. This is because most fruit and nut trees are grafted. Grafted trees have an aboveground part from one variety and a root stock from another variety. This is done to take advantage of one variety’s ability to develop strong roots, while other varieties may taste better or be more pest or disease resistant. Also, your pit grown peach tree will not produce fruit for a few years, and some will never produce fruit.

If you want to give it a try, you can simply put your peach pit in the ground and let nature take its course, or you can refrigerate the pit until December or January. This method, called stratification, fools the pit into triggering winter processes (vernalization), in preparation for spring. Just soak your pits in water for a couple of hours, and then place them in a plastic bag, along with a little moist soil. This bag goes into the refrigerator, until you see signs of germination. This can take a few weeks or months, depending on the variety and other factors. Since peaches emit high levels of ethylene gas (a ripening agent), you should keep them away from other fruits and vegetables. Once it starts germinating, remove it from its cold environment and let the planting begin! But first, you need to select the best location for your peach tree.

Peach tree site selection

Peach trees need plenty of sunshine, but they will also benefit from a little protection at the extreme points of summer and winter, if possible. Being susceptible to several fungal diseases, peach trees also need good drainage. Peach trees prefer a soil pH of 6.5. Here, in the Bay Area, we tend to have more alkaline soil, so acidification may help your tree thrive. Of course, you won’t know what your soil is without a test from a reputable lab. Just sayin’…

How to plant a peach tree

Bare root trees are best planted in January and February. Your peach sapling should be planted right away, or soaked in water for 6 to 12 hours before planting. If you have a bare root tree, gently spread the roots out to see how much space they can use and dig a hole that will accommodate them. This is also a good time to clip off any dead, diseased, or damaged roots. Be sure to rough up the edges of your planting hole. If you don’t, the smooth clay left by your shovel can create a tough barrier for young roots. Containerized and balled trees should be given a hole slightly larger and the same depth as the container or root ball. It is very important that the soil level remains the same. Add soil around the roots and gently tamp it down. This removes air pockets that can dry roots out before they ever get a chance to grow. Mulch around your new tree and water it in well. Peach trees can also be started from twig cuttings called scions.

Peach tree care

Peaches are self-pollinating, which means that another tree is not needed to produce a crop. If you have room for more than one tree, be sure to space them 12 by 16 to 18 by 18 feet apart. Peaches perform best when trained with what’s called the “Y” system. The “Y” system features two scaffolding (main) branches, heading in opposite directions, creating a “Y” shape. You can picture it as a two-dimensional open center system, which also works with peaches. These tree training systems leave the trees open in the center, allowing lots of air and sunlight to reach the fruiting wood. Peaches can also be espaliered.

​Feeding and watering peaches

Peach trees use a lot of nitrogen. You can use blood meal, ammonium sulfate, or commercial 10-10-10 fertilizer to feed your peach tree. Nitrogen deficiencies in peach appear as red areas on the leaves. Peaches are shallow-rooted, so they are susceptible to water stress during the summer. Too much stress can lead to a condition called bitter fruit that can mean the end of the useful production of your tree, so irrigate accordingly. Near the end of fruit development, deficit irrigation can be used to improve taste and sweetness.

While you certainly want to avoid girdling your peach tree with the weedwacker, doing it on purpose, called cincturing, or scaffold girdling, can increase production and fruit quality. You just have to be really careful that you don’t kill your tree in the process.

Peach pests and diseases

Peaches are susceptible to these bacterial diseases: crown gall, bacterial blight, citrus blast, and bacterial spot. Fungal diseases include stem blight, peach leaf curl, shot hole disease, and brown rot. Armyworms, peach twig borers, earwigs, eugenia psyllid, Japanese beetles, mealybugs, San Jose scale, green fruit beetles, Mediterranean fruit flies, armored scale, eriophyid mites, katydids, and birds are the biggest pests. Luckily, beneficial insects, such as braconid wasps, mealybug destroyers, and tachinid flies love to eat peach twig borers!

Pheromone traps can be used to monitor many of these pests and sticky barriers will prevent many pests from ever reaching tender buds, shoots, and fruit. Bordeaux mixture, fixed copper, and dormant oil can be used to prevent or treat some bacterial diseases, fungal diseases, and pest infestations. Kaolin clay can also be used to prevent some pest damage. Since fruiting occurs from pollination by honey bees, flies, and other pollinators, avoid using broad spectrum pesticides. 

When to harvest peaches

Color and smell are good ripeness indicators, when it comes to peaches. Yellow skin, which may or may not have a red tinge, and that amazing sweet summer aroma of ripe peaches are reason enough to give one a try. Taste, ultimately, is the only true indicator of ripeness, but who can complain about conducting that test? If the fruit comes away from the stem easily, it is ripe.