Pumpkin pie, pumpkin pudding, pumpkin bread, and the ever-popular Halloween jack-o-lantern are all autumn favorites. But, did you know that most canned pumpkin puree is actually squash?
Being members of the squash family (Cucurbita), pumpkins and other winter squash share enough characteristics as to be indistinguishable according to the FDA. Huh. How about that? So much for truth in advertising. No matter. Growing pumpkins is rewarding and not nearly as difficult as you may think.
The story of pumpkins
Pumpkins are native to North America. Early Native Americans grew pumpkins along with maize and beans in the Three Sisters Method. This sustainable gardening method combines the nitrogen-fixing ability of beans with the climbable maize (or corn), and the soil protecting, weed preventing shade provided by broad squash leaves. Ripened pumpkins were roasted over fires, baked in dirt ovens, parched, and boiled. They dried pumpkin flesh and used it as flour, and dried the outer shells to be used as containers. Pumpkin blossoms were added to soups and stews, and any seeds that were not saved for the next year’s crop were roasted for as tasty snack. I don’t see any reason why we shouldn’t be using this durable and attractive plant in the same ways in our own gardens.
How to grow pumpkins
Pumpkins are now grown everywhere except Antarctica, as human and livestock food, and for use as autumn decorations. Now, I love seeing those round orange signs of a good harvest on porches and patios, but it kills me to see them tossed to the curb, many of them never even opened. What a waste! Unopened pumpkins can always be donated to local food banks, if nothing else. Personally, I put my pumpkins to work for my own family. The easiest way possible, is to simply let nature take its course. You can put a pumpkin in a suitable location to go through all the natural cycles and just leave it alone.
If you prefer a more focused effort, you will need seeds. It can start with a store bought packet, seeds from a friend’s pumpkin, or your own current pumpkin. Jack-o-lantern or not, I will eventually cut into my pumpkins. I can put this off for quite a while because pumpkins and other winter squashes, such as butternut, have one heck of a shelf life, if they are cured correctly. We’ll get to that in a minute.
Cutting open the pumpkin, you will find a treasure trove of seeds inside. I remove the seeds and separate them from the stringy threads that nourished them (my chickens love that stringy stuff!). I choose the fattest, firmest seeds for next year’s crop, placing them inside a folded towel to allow for air flow without sun exposure, until they dry. The rest are soaked in a brine and roasted for a family favorite.
After temperatures have reached a steady 70ºF, those saved seeds are planted in hills, or mounds, of loose soil amended with aged compost or manure. The hills improve drainage and the soil warms more quickly. Pumpkins are very heavy feeders and their seeds are temperature sensitive. Each pumpkin plant can take up to 50-100 square feet, given the opportunity. You can also redirect vines along walkways, lawns, or fences. Plant 4 or 5 seeds 1” deep in each hill. If you have room for multiple hills, they should be spaced 4 to 8 feet apart. After your seedlings are 2 or 3 inches tall, select the best 2 or 3 for each hill and snip the rejects off at soil level. This causes the least amount of disturbance to young roots and important soil microorganisms. If you are growing pumpkins in rows, rather than hills, seeds should be planted 6 to 12 inches apart in rows that are 6 to 10 feet apart, thinning seedlings to one plant every 18 to 36 inches.
Caring for pumpkin plants
It takes a lot of water to make a pumpkin. During fruit set, each pumpkin plant should receive approximately one inch of water per week. (One inch of water is equal to 0.623 gallons per square foot.) When watering, try to avoid getting the leaves wet, as this can promote fungal diseases. Mulching around pumpkin plants will help conserve water, stabilize temperatures, and reduce competition with weeds. Since pumpkins are shallow-rooted, it is not a good idea to disturb the soil. If you only have a small space, pumpkins can be trained up a trellis. Depending on the size of the fruit, you may need to provide hammocks as support.
How to hand pollinate pumpkins
One common problem with pumpkins is insufficient pollination. You can pollinate your pumpkins by hand for a bigger crop. To hand pollinate, you must first learn the difference between male and female flowers. It’s not hard. Male flowers tend to open earlier in the growing season and they feature a stalk that emerges from the center of the flower called the anther. If you touch the anther and your finger comes away dusted in yellow, it is ready to use for hand pollinating. Simply cut the male flower off and remove the petals to create a “paintbrush of pollen”. Female flowers contain an ovary, which looks like a small ball at the base, outside of the petals. Male flowers do not have this structure. Once female flowers begin to open, simply use the anther paintbrushes to apply pollen to the nubby bits (stigmas) in the center of the female flower. If pollination is successful, the ovary and the base of the flower will begin to swell, ultimately becoming a mature pumpkin.
Pumpkin pests & diseases
The most common problem I have had with pumpkins are powdery and downy mildews, with an occasional bout of blossom end rot. Weeks will go by and the leaves will stay bright green and healthy and then, it seems suddenly, the leaves are covered with fuzzy white and gray areas, top and bottom, and production slows to a near halt. Pumpkins are susceptible to other fungal diseases, such as Verticillium wilt, root rot, damping off, and curly top, but I have not experienced any of those in my garden. Many insect pests also enjoy pumpkins. Crickets, earwigs, several types of beetles, stinkbugs, wireworms, whiteflies, thrips, nematodes, armyworms, spider mites, aphids, and, of, course, slugs and snails. Looking at this list, it’s a wonder that pumpkins grow at all, but grow they do!
Pumpkins are ready to harvest when the shell is firm and the stem is shriveled. After removing the fruit from the vine, allow it to dry, or cure, for a couple of weeks in a location with plenty of airflow and cool temperatures. Garages work nicely. After your pumpkin has cured, it will remain edible for several months.
Give pumpkins a try in your garden!
Spinach isn’t just for cartoon sailors! This delicious member of the amaranth family can hold its own in your garden, on a window sill, or growing on a balcony. Cousin to beets, quinoa, and chard, spinach lives up to its reputation as a nutritional powerhouse, but not for the reason you think.
Cartoonists weren’t exaggerating when they showed how spinach pumped up our beloved sailor man, but iron isn’t the reason. A single cup of fresh spinach provides 56% of the RDA for Vitamin A, 15% folic acid, 14% Vitamin C, 13% manganese, and 181% Vitamin K, and all for less than 7 calories. Spinach only contains 5% of the RDA for iron, but it does provide high levels of carotenoids, which helps prevent cataracts, and many other important nutrients.
As children, many of us cringed at the mere mention of spinach. Part of that was due to canned and frozen varieties being cooked into a stringy, slimy, green ooze. It also reflected the fact that a child’s taste buds are more sensitive to bitterness that an adult’s. Now that we are older and wiser, however, we can truly enjoy the crisp, refreshing, delicious flavor of a spinach salad. And freshness is the key. In fact, while working as a USMC Family Childcare Provider, I overheard a conversation that no one expects to hear: one toddler admonishing another toddler to not eat so many spinach leaves because it would damage the plant! You can read more about that here.
Spinach seeds & leaves
Much of the spinach sold in American grocery stores is the light to dark green, smooth, oblong- or triangular-shaped leaf variety. There are also varieties with distinctly crinkled leaves. This characteristic earns them the name ‘savoy’, after a cabbage with similar tendencies. Savoy spinach varieties produce thicker, more rounded leaves. There are also crosses between the two, called semi-savoy. Now, if you have ever planted spinach, you know that the seeds are rather large, especially when compared to other greens. Spinach seeds come in two forms: prickly and smooth. You might expect the smooth seeds to produce smooth leaves and vice versa, but it’s just the opposite. Smooth seeds tend to produce crinkled (savoy) leaves, while prickly seeds tend to produced smooth leaves.
Spinach (Spinacia oleracea) is an annual that tends to bolt, or go to seed, as soon as temperatures rise. Bolting makes the leaves lose their flavor, but it can also provide you with seeds for your next spinach crop. You can collect your own seeds, as long as you do not plant hybrids. [Hybrids generally do not produce plants that look or taste like the parent.] You can also let them fall where they will, as I do. They always seem to find the spots that suit them the best.
Most varieties of spinach are dioecious, which means there are male plants and female plants. The ‘Bloomsdale’ variety is monoecious, which means each plant is both male and female and can self-pollinate. Spinach grows relatively fast. You can have harvestable spinach within 3 weeks, so you may want to stagger your plantings for a continuous crop. This is called succession planting. Or, you can allow your spinach plants to go to seed naturally, which can provide a perpetual bed of spinach for most of the year, plus the flowers provide nectar and pollen for many beneficial insects.
Spinach pests & diseases
Spinach is susceptible to many fungal diseases, including downy mildews, rust, fusarium wilt, and Pythium. The Rhizoctonia parasite can also attack your spinach plants. Aphids, crickets, earwigs, flea beetles, cutworms, darkling beetles, bulb mites, leaf miners, loopers, nematodes, seedcorn maggots, slugs and snails, wireworms, whiteflies, rabbits, and chickens can also wreak havoc on your spinach plants. Personally, I conduct a weekly leaf inspection of my spinach and beet plants. A quick peek under each leaf makes it easy to wipe off whitefly eggs before they can hatch. These eggs look like clusters of tiny white rectangles.
How to grow spinach
Spinach can be added to flowerbeds, next to walkways, at the base of peas and other climbing plants, and anywhere else these fast growing greens will look nice. As a cool season crop, spinach can be started directly in the ground anytime between late August through April, here in San Jose, California. Spinach prefers sunny locations during cooler weather and some shade protection during hotter months. You can also grow it indoors, in containers, year round, if you have a sunny window or grow lights. Containers should be at least 8” deep.
Seeds should be planted 1/2” deep and kept moist until germination occurs. Seedlings should be transplanted at a time when they are most likely to survive, which means when temperatures are not scorching. Transplants should be spaced 8 to 10” apart. The same is true for seeds sown directly in the ground. You can make your soil more conducive to spinach by topping dressing the bed with some aged compost ahead of time. Spinach favors lighter, sandier soil than we tend to have here and it is a heavy feeder. You can add nutrients by side-dressing, which means placing aged compost around and next to plants once they are in place. As you water, the nutrients will leach into the root zone and be absorbed by the plants. Spinach prefers a pH of 6.5 to 7.5. Spinach plants have shallow roots, so be sure to water regularly, especially as temperatures begin to rise.
Some varieties of spinach perform better when grown in the fall, while others prefer spring. I keep seeds of several varieties handy so that I can maintain a constant supply of fresh spinach throughout most of the year. Be sure to read the packet before you start planting.
Since spinach only grows successfully in hot regions during during the cooler months, you can grow other plants during the summer that provide similar taste and nutrition. These plants are:
Spinach history & trivia
Spinach was first grown in Persia, around 500 B.C. The “Persian vegetable”, as it was called, was brought to China in the 7th century. Two hundred years later, spinach seeds made their way to Italy. Florence’s Catherine de’ Medici loved spinach so much that foods served on a bed of spinach became known as “Florentine”. Another five hundred years pass before spinach has a home in western Europe, appreciated for appearing in early spring, when food is scarce, and by not breaking any religious food rules. Spinach was even included in the first known English cookbook in 1390!
Weevils are a type of beetle that loves to eat plants.
Most weevils are small (less than 1/4” to 1/2” long), somewhat triangular in shape, dark gray, brown, or black, with some markings, elbow-jointed antenna, and they all feature the telltale snout that distinguishes them from other insects. Most weevil larva are white or pink, C-shaped, only 1/3” long and legless, with a brown head. The Fuller rose beetle larva has a white head and the vegetable weevil larva is green.
The weevil family
There are over 60,000 different types of weevils worldwide and more than 1,000 in California.
Being so large, the weevil family is divided between true weevils (Curculionidae) and primitive weevils (Orthoceri). The division is unimportant from our standpoint, but it is important to understand the damage weevils can cause in the garden and in your pantry, how they live, and how to avoid infestation. Some of the more common weevils found in California, and their foods of choice, include:
Adult weevils hide in the soil during the day. Weevils generally attach their eggs to a food source or lay them in cracks provided by pods, stems, and other plant structures. Some species lay their eggs in the soil near host plants. When the eggs hatch, the larva burrow into the nearby food source, where they gorge themselves before metamorphosing into a pupal stage, and then into adulthood. Adults emerge June through September, leaving small round holes in seeds as the only sign of infestation. Weevils can destroy crops in the field or harvested produce while in storage. Not only do weevils feed on your produce, they also leave behind frass. Most weevils are flightless and nocturnal, so all we may see are signs of infestation.
Weevils are known for burrowing into beans, cotton bolls, and cereal grains, but they also feed on roots, stems, buds, flowers, leaves, and fruit. Often, the first sign of infestation is leaf wilting, early fruit drop, scalloped leaf edges, and damaged seeds.
Controlling weevils is mostly a matter of prevention and sanitation. First, only install plants that are weevil-free. Then, make sure that old beans, pods, seeds, and other plant debris from previously attacked crops are not left in the field. Crop rotation can help a lot, since many weevils are host specific. Infested areas should be plowed or dug and allowed to go fallow (unused) for 2 or 3 months to starve any weevils in the soil. Sticky material can be used around tree trunks to protect against soil borne weevils, but it will do nothing against plants that are already infested. Insecticides are marginally effective, but fumigants and parasitic nematodes are used commercially with some success. Nettle, mustard, cheeseweed (little mallow), and oxalis are also host plants, so you may want to keep them away from your garden if weevils have been a problem.
For those of you who can't hear the word "weevil" without thinking of the blues song, here's your link.
Dormancy is a plant’s response to adverse conditions, such as too much cold, too much heat, or not enough water. During dormancy, a plant’s growth, development, and reproduction are slowed or halted until conditions improve. Hibernation refers to a mature, viable seed that has not germinated because of unfavorable conditions.
Dormancy is a protective measure that increases a plant’s chances at long term survival. Imagine what would happen to your apricot crop if all the buds emerged in November. There wouldn’t be many honey bees or other pollinators around, and the fruit, if it could form at all, would probably end up frozen mush on the tree, even here in the Bay Area.
Dormancy is classified as either predictive (endo-dormancy) or consequential (ecto-dormancy). Consequential dormancy is what happens in response to external conditions, while predictive dormancy occurs because of internal processes. The perfect example of predictive dormancy is the way deciduous trees and vines pull nutrients from their leaves and let them fall. This is caused by chemicals that inhibit growth and help the plant prepare for winter temperatures. These chemical changes are usually triggered by shortening hours of light and lower temperatures, and sometimes by rainfall levels. The same is true for seeds. Plants will remain in predictive dormancy until they have accumulated enough chill hours. After that point, they are in consequential dormancy, also known as delayed-dormancy, until spring comes.
Winter dormancy and chill hours
Many fruit and nut trees (and wheat!) require a certain amount of winter dormancy to produce a good crop the following summer. Somehow, somewhere within these trees is an amazing mechanism that tracks the number of hours of dormancy that are spent above freezing temperatures. These are called chill hours. Depending on the species and variety, the chilling requirement can be anywhere between 500 and 1500, or even more. This is why it is so important to select plants that are suited to your microclimate. You may do everything else right, irrigation, fertilizing, weeding, and you still won’t get a crop if your plant needs more chill hours than it can get in your garden. Also, all temperatures are not the same when it comes to fruit trees and chill hours. The most effective chills are between 40oF and 50oF. Temperatures below or above that range are less effective, and temperatures above 60oF can interfere with accumulated chilling hours.
Dormancy and cold hardiness
While plants are dormant, they are able to acclimate to colder temperatures. This is called cold hardiness. Once a tree or shrub has entered dormancy, it can withstand subfreezing weather and still put out buds in spring. Berries, such as raspberries and blackberries, also need a cold period of rest to perform better in the next season.
Tree care during dormancy
Winter provides the perfect time for pruning and many pest management activities. In the Bay Area, trees are usually fully dormant in December and January. Delayed-dormancy runs from February, when buds start swelling, through the point where buds reach the stage where their tips are green. Use periods of dormancy for these garden tasks:
*WARNING: DO NOT APPLY OILS 30 DAYS BEFORE OR AFTER SULFUR APPLICATIONS
Fertilizers and dormancy
In most cases, fall and winter are not the time for fertilizers. Nitrogen, in particular, can stimulate new bud and leaf growth, despite colder temperatures. These tender new tissues are doomed from the start and can create points of entry for many pests and disease.
Frost damage: prevention and response
As frost damages the aboveground portion of many plants, our first instinct is to remove the ugly, damaged leaves and stems. While that may make things look nicer, it is actually harmful to many plants. The root system may still be able to absorb many of the nutrients stored in those frozen leaves, and the damaged plant tissue provides a blanket of sorts, to protect the roots against even colder temperatures. If you really can’t stand the look of frost bitten plants, you can prevent the damage with protective fabric, or cover dormant plants with straw.
For the most part, periods of dormancy are normal, natural, and good advice for the rest of us.
Straw bale gardening is touted as providing all the benefits of raised beds without the cost. Poor (or absent) soil can be overcome by growing vegetables in bales of straw. Also, if your soil is host to Verticillium or Fusarium wilt, nematodes, or really tough weeds, straw bale gardening may be the answer. Or, it may not.
These preconditioning steps are needed for successful straw bale gardening:
When are my straw bales ready for planting?
If synthetic fertilizer is used, you can start planting on Day Twelve. If organic fertilizers were used, wait until Day Seventeen. Before you start planting, however, you need to consider other potential problems.
Potential problems with straw bales
Aside from decomposition and the need for frequent watering and fertilizing, straw bales are often produced in fields where persistent herbicides are used. These herbicide do not breakdown quickly and they can adversely affect your crops, your compost pile, and your soil. If you do not know for sure, you have to assume that these chemicals are present and are best avoided. If you can find organic straw bales, you are ready to move forward.
Seeds vs. transplants
Crops that are grown from really tiny seeds, such as lettuce, are best started in potting soil and then transplanted to the straw bale garden. Otherwise, those tiny seeds will end up somewhere in the middle of your straw bale where the only thing they can do is decompose. Adding a shallow layer of potting soil on top of your straw bales can also eliminate this problem. Use a trowel to open up a space in the straw bale for transplants and be sure to water after adding plants or seeds.
What can be grown in a straw bale garden?
Each bale of straw can be used to grow a surprising variety of plants. You can grow 2 or 3 tomato, squash, or melon plants, 4 or 5 pepper plants, or as many as 15 bean plants in a single bale. You can also grow potatoes. The most critical issues of a straw bale garden are water and nitrogen. If either of these are in short supply, your plants will suffer.
Feeding and watering a straw bale garden
Drip emitters and soaker hoses are your best bet for a straw bale garden. Early in the growing process, more water will be needed as plants send roots throughout the bale. Since straw bales are not soil, it is important to monitor your plants for signs of nitrogen deficiency. Stunting and chlorosis (yellowing) are the two most common signs. Normally, monthly feedings will be sufficient.
Until your straw bales completely decompose, you can have multiple plantings, especially if you keep tightening the twine. As the bales decompose, they will shrink. You can keep them compressed by tightening the twine with a stick inserted behind the twine and rotated over the twine as many times as it takes to keep it tight, tucking the stick behind the twine.
Straw bales gardens may last for more than one season, but they will ultimately decompose. Once the bales are unusable as growing mediums, they can be added to the compost pile or used as mulch.
What have you grown in a straw bale? We’d love to see photos!
After adding slug and snail bait to my Napa cabbage patch more times than I thought I should have to, I took a closer look and discovered a “new” pest in my garden: millipedes.
Now, millipedes have been around for over four hundred million years, making them one of the oldest land animals. Lucky for us, those prehistoric millipedes are no longer around, since some of them were over SIX AND A HALF FEET LONG! Yikes! Thank goodness that our little garden millipedes are profoundly smaller!
Despite their name, which means thousand legs, none of them have that many. Most varieties have 30 to 90 pairs of legs. Millipedes have antennae with seven segments. Most millipedes are brown or black, but there are orange and red species.
Millipedes vs. centipedes
Unlike centipedes, which are carnivores, millipedes are vegetarians. While both have segmented bodies, centipedes have one pair of legs per segment, while millipedes have two. Millipedes are decidedly slower than centipedes, but they can devastate young seedlings (and Napa cabbage). While centipede bodies tend to be flat, millipedes are more cylindrical. It’s probably not a good idea to handle millipedes (although some people raise larger varieties as pets), since many of the 12 to 80 thousand varieties secrete defensive chemicals when threatened.
Millipede diet & lifecycle
Millipedes prefer burrowing in dark, damp areas, so it’s no surprise I haven’t seen them. They lay eggs and overwinter in the soil. Garden centipedes are usually only 1/2 an inch long, though they can reach over 6 inches. Surprisingly, millipedes can live for several years. In addition to eating vegetation, millipedes are known as detritivores, which means they eat dead stuff that’s mostly plants and poop. There are a few omnivorous and carnivorous millipedes, but they are no problem in the garden. When a garden millipede is disturbed, it will curl up into a coil. Here in California, we have three species of garden millipede:
Chemical controls, such as pesticides, are not effective against millipedes. The best way to cut millipede populations in your garden is to reduce moisture levels and increase air flow. My millipede problem has been occurring in a raised bed that contains large, feathery fennel, broad leafed rutabagas and, yep, you guessed it, Napa cabbage. Apparently, the other plants are holding all that precious water just as I had hoped, never realizing that I would be creating the perfect habitat for a pest that would skeletonize all of my Napa cabbage plants. So, here’’s the list of tips for reducing our millipede populations:
Weird notes on millipedes: the study of millipedes is called diplopodology and the people who do the studying are called diplopodologists. Also, Venezuelan Capuchin monkeys rub themselves with millipedes because those defensive secretions are a natural mosquito repellant, which prevents freeloading bot fly eggs from hatching and embedding themselves in the monkeys’ skin. Don’t care - not doing it.
I am okay with bugs. For the most part, I find them fascinating. I collect them, look at them through a hand lens or a microscope and then, depending on whether they are beneficials or pests, free them or feed them to my chickens. Centipedes have always been an exception, until recently.
Many years ago, I lived on Oahu, where centipedes get really big. When I say really big, I mean up to a foot long and over an inch wide! If that weren’t enough, centipedes can deliver a venomous bite that is said to feel like a bad bee sting. These prehistoric monsters will actually raise part of their body up, weaving in the air threateningly, and then chase you down a hallway. And they are tough! You can’t kill them by stomping on them in your sneakers. You need a hammer or a heavy duty coffee cup. Believe me, I speak from personal experience. The giant centipedes of the Amazon (Scolopendra gigantea) actually feed on lizards, mice, and even birds and bats that are caught in flight! Centipedes give me the heebeegeebees!
The tiny centipedes in my garden, however, are an entirely different story.
So what are centipedes?
Centipedes are not insects. Insects have three main body parts and three pairs of legs. Centipedes have segmented bodies and many, many legs. In fact, their name is Latin for hundred and foot, but they can have many more or less than one hundred. With all those feet, centipedes can move pretty darned fast. Can you imagine keeping track of all those feet? In 1871, Katherine Craster wrote The Centipede’s Dilemma:
A centipede was happy – quite!
Until a toad in fun
Said, "Pray, which leg moves after which?"
This raised her doubts to such a pitch,
She fell exhausted in the ditch
Not knowing how to run.
There’s nothing like overthinking to mess yourself up, right? Well, centipedes have evolved to grow each new set of legs a little bit longer than the pair in front. Scientists believe this is so the insects don’t trip over themselves, but the centipede’s first pair of legs evolved in a completely different way. They are venomous graspers, called maxillipeds, which are used to hold and inject their prey with paralyzing venom. Luckily for us, most centipedes are too tiny to pose a threat to gardeners in the field.
Centipedes can be pale grey, but mostly they are dark red or brown. Scientists estimate that there are 8,000 species of centipede. Only 3,000 species have been found so far and they are everywhere. There are even centipedes within the Arctic Circle!
Centipedes hide in leaf litter, under stones, and in logs. They lack the waxy cuticle, or outer layer, that most insects and spiders have, so centipedes lose water very quickly. They also do not have eyes in the proper sense. They can discern light and dark, but that’s about it. Most species of centipede hear and feel vibrations through their antenna.
There are five orders of centipedes:
Centipedes in the garden
The beloved garden centipede is completely blind. Its highly effective antennae has 14 segments that seem to make up for being eyeless. Being carnivores, your garden centipedes will spend their nights looking for insect larvae, soil-dwelling mites, baby snails and slugs, and worms. This puts them firmly in the category of beneficial insects, in my book.
If food becomes scarce, garden centipedes may also begin feeding on the roots of cabbage and other garden favorites, but this is usually the work of millipedes and not centipedes.
You may not know it, but you’ve probably seen downy mildews on several plants in your garden. The symptoms can be different for each type of plant, but the first thing that most people notice is angled dead areas on the tops of leaves. Closer inspection reveals gray, blue, white, or lavender fuzzy areas on the underside of the leaf. That’s downy mildews.
Most of us are familiar with the fuzzy white spots on leaves and stems that indicate powdery mildew. Powdery mildew is a fungal disease. The white areas we see are colonies of tiny fungi. Until recently, scientists thought that downy mildews were simply a different breed of fungi. Now we know that downy mildews are actually a whole new collection of tiny algae-like microbes (oomycetes) that parasitize vascular plants to complete their life cycle (obligate parasites or holoparasites).
Figuring out if your plants are infested with powdery or downy mildews is important because the treatments are different.
Downy mildews symptoms
As downy mildews set up household on your plants, you may not notice those gray, white, blue, or lavender fuzzy areas (sporulations) that eventually turn gray or black, or threadlike growths (mycelium) on lower leaf surfaces. Only after the lower leaf tissue is dissolved and absorbed by the downy mildews organisms will it become obvious, as the upper leaf surfaces turn yellow and die. These leaf lesions commonly have angular shapes that stop at leaf veins.
Some varieties of downy mildews can also grow inside your plants, leaving black streaks visible in stems and flowers. Other downy mildews symptoms are mistaken for gray mold (Botrytis). Remember, downy mildews isn’t a single life form. There are dozens of downy mildews. Another issue with downy mildews is that each host plant species may show different symptoms. In fact, sometimes the symptoms on different cultivars of the same species look very different. The only consistency is the fuzzy areas on the underside of leaves and discolored upper surfaces.
I’m sure there are some vascular plants that are not impacted by downy mildews, but I don’t know what they are. Downy mildews have evolved in tandem with countless host plants, pushing the evolutionary envelope ever forward. Here is just a small sample of the downy mildews you may encounter, and their host plants (and don't let the Latin scare you!):
Researchers believe that some species of downy mildews, especially the one that attacks cucurbits, actually follow ripening crops northward every growing season. Most of these microorganisms cannot handle the cold, though some overwinter in leaf litter, soil, and on seeds or plant debris.
Downy mildews control
Unlike true fungi, which cannot swim in the water that collects on leaves, downy mildews can and will. This means that the longer your plants’ leaves are wet, the more likely they are to become infested. Wet morning leaves provide the perfect growth medium, while dry, warmer afternoons allow spores to catch a ride to nearby plants on the slightest breeze. Because of this, sanitation and air flow are your best friends when battling or preventing downy mildews. These microorganisms prefer cool, damp conditions. When temperatures are between 50-75°F and relative humidity is above 85% (welcome to California winter), these microorganisms start reproducing like crazy. These tips can help reduce the likelihood of downy mildews in your garden and landscape:
Plants affected by downy mildews should not be eaten. I don’t know if it’s dangerous or not, but the pros say the flavor is altered and unmarketable. Doesn’t sound very good, does it?
Do any of your garden plants show signs of downy mildews?
Isn’t this the weirdest lemon you have ever seen?
This fruit has been infested by the citrus bud mite. Just as the name implies, citrus bud mites (Aceria sheldoni) attack those fragrant citrus flowers and buds, causing a distorted rosette growth pattern of the surrounding leaves, flowers, and fruit.
These pests are normally found on lemons and other citrus grown in coastal regions, but Southern California has been seeing them move inland, so they will probably become more of a problem here in the Bay Area before long.
These citrus pests are really tiny. They can only be seen with a 20x hand lens or under a microscope. Citrus bud mites have a tapered yellow or pink body and four legs that look like they are growing out of its head. [For anyone who has read this blog for any time at all - these bizarre descriptions are surprisingly normal - fiction has nothing on real life!] These pests are active year round.
Each summer, females lay up to 50 eggs in the tiny scales that are supposed to protect tender new buds. When the eggs hatch, the young go through 4 instars before maturing. Commercially, citrus bud mites can be a real problem, but most home orchards only see a few affected fruit, and it is still edible. [I’ll bet horizontal slices would actually look pretty amazing… but peeling it would be a nightmare!]
The real problem with these pests is that the distorted shapes caused by their feeding create the perfect hiding spot for other citrus pests, such as citrus mealybugs and the two-spotted spider mite. Researchers have tried using horticultural and dormant oil treatments and found them ineffective, since the pests are in a protected space. If signs of citrus bud mites are seen, you may simply want to monitor fruits for signs of other pests who are taking advantage of the prime real estate.
Have you ever had citrus bud mites in your fruit? I would love to see photos!
Moss is a prehistoric plant. It has no flowers, no roots, and it reproduces the same way mushrooms and other fungi do, using spores. While many people consider moss to be a sign of too much moisture (which it can be), I love how it looks on my chicken coop’s thatched roof.
Moss has been around for a really long time, some estimate 470 million years, and it evolves 2 to 3 times more slowly than most other plants. Unlike lichens, hornworts, and liverworts, which are also really old, but more complex, mosses are too fragile to leave behind much of a fossil record. Recent research, however, has shown that mosses may be responsible for the Ordovician ice age, some 200 million years before dinosaurs even existed!
Currently, there are over 12,000 varieties of moss. Sphagnum, or peat moss, is commonly used as burnable fuel, in floral arrangements and crafts, and it has one rather odd characteristic: peat moss alternates living cells with dead cells. Those dead cells are used to store water. Using this method, some mosses can absorb up to 20 times their weight in water! And water is critical to moss fertilization. Moss can tolerate being completely dried out for months, but one quick rain and BAM! They are back in business!
When I lived in Virginia, trying to keep moss out of the lawn was a constant battle. My neighbors thought I was nuts when I finally stopped fighting the moss and actually started encouraging it to grow. Moss prefers acidic soil, which Virginia has plenty of, so I used equal parts moss and sour milk in a blender and poured it wherever I wanted more moss. End result: my “lawn” was always flat, always green, always soft, and never hung on to fallen leaves. It looked and felt lovely. In Japan, entire gardens are dedicated to the quiet beauty of mosses. Moss can be used to cover stones and other structures, softening the edges and adding a sense of tranquility. Moss can also be used to create living art that may surprise you!
So what is this tiny primitive plant we call moss?
The green mats we see covering rocks and roofs and filling cracks in sidewalks are actually millions of tiny plants clustered together. Moss is profoundly simple. It is actually easier to describe moss by what it isn’t: no roots; no flowers; no seeds; no vascular tissue. Each moss plant consists of simple leaves that are only one cell thick, with no air pockets, and a stem that can be branched or unbranched. After a moss plant is fertilized, you can see a tiny stalk emerge with a single capsule at the end. This capsule contains spores called sporophytes. One species of moss, Dawsonia, has a stalk that grows up to 20 inches long! You may also be surprised to learn that mites and springtails act as pollinators for mosses! Male and female mosses emit different aromas to attract these helpers! Who knew?!!? There are also mosses that can reproduce vegetatively, using a leaf or branch that has broken off to start a new plant.
The weirdest thing about moss reproduction is something called nannandry, or dwarf males. This means that male spores that land on or close to a female spore become dwarf-sized, while male spores that land too far away become female-sized. Scientists believe this is because larger spores are more likely to be carried closer to a female by external means. Weird, right?
While there are no actual roots, mosses do anchor themselves to surfaces using threadlike rhizoids. Contrary to popular belief, mosses do not feed on the substrates to which they are attached. They do, however, secrete acids that dissolve the rocks and wood they cover. Mosses get their water and nutrients by absorbing them directly into their cells, often as rain falls on them or water flows over them. Moss plants also use photosynthesis for some of their energy. Mosses can be found in sun or shade, wet areas, on alpine rocks, and even on sand dunes! While mosses are commonly found on roofs, streets, and sidewalks, they are generally classified according to these traditional substrates:
If you were a moss, what would your substrate be?
Slow growing moss, cloaking everything it touches, has inspired some funny words:
Finally, the old rumor about moss growing on the north side of trees is bogus. Moss grows on the wet side.
Masked chafers are underground bandits. They devour turfgrass roots all summer long, but the damage isn’t usually seen until late summer or early fall.
I couldn’t figure out why I had so many odd-shaped dead patches in my lawn. I watered and fed it all the same. In spite of my heavy clay soil, there were areas that felt spongy and didn’t look very healthy. When I grabbed a handful of lawn and gave a gentle tug, entire patches came up like a bad toupee. Also, one of my dogs kept digging shallow holes, even though she knew it was strictly forbidden. She could hear what I could not. It was masked chafers.
Masked chafer description
Masked chafer beetles (Cyclocephala borealis) are small (3/4”) brown beetles with a black head. The larvae are fat grubs that live underground. They are about an inch long, white with a brown head and a brown stripe down the back. Masked chafer grubs tend to curl into a C-shape when exposed or disturbed. There are two other species grub that you may discover in your lawn: June beetles and black turfgrass ataenius grubs. The June beetle grub has two rows of bristles on the underside of its rear end (raster), while the masked chafer has scattered bristles, and the black ataenius has something of a wasp-waist. Whichever species is feeding on your lawn, you’ll want to get rid of it.
Masked chafer host plants
Masked chafers prefer bluegrass, ryegrass, and other warm season grass species, but all turfgrass species are vulnerable. So are your blueberries. Masked chafers burrow underground, feeding on roots and cutting off the supply of water to your lawn. The first symptom of masked chafer infestation is the lawn looks drought-stressed. Well, here in California, all lawns look drought-stressed by the end of summer, so that doesn’t help. The symptoms also look similar to Southern chinch bug damage. The only way to really be sure about the presence of masked chafers is to watch for them whenever digging in the garden or landscape. If you have areas that look like masked chafers may be a problem, it may be worthwhile to grab your shovel and make a shallow cut, under the grass roots, to see what’s really going on down there.
Masked chafer controls
Keeping your lawn healthy is the best treatment. That means planting the right variety for your microclimate, watering it deeply and infrequently, and feeding it appropriately. Avoiding the use of broad-spectrum pesticides will also help maintain a population of beneficial insects that may parasitize the grubs. You can learn more about the best turfgrass variety for your area in UC Davis’ Turfgrass Selection for the Home Landscape. Experts say that one grub per square foot of lawn is okay, but six is not. You decide what’s right for your lawn.
You can buy a variety of parasitic nematodes that are advertised to kill off these pests, but not all of them work. Research at UC Davis has shown that Heterorhabditis bacteriophora is effective against masked chafers, while Steinernema bacteriophora are not. When I applied parasitic nematodes to my heavily infested lawn, I was rewarded the next morning with grubs on my patio. They may not move quickly, but they sure didn’t want to stay in my lawn! The hens were very happy about that and so was I!
Leeks have a nice delicate flavor, but they can get pretty pricey in the grocery store. Luckily for us, they are easy to grow!
Unlike other members of the Allium family, such as garlic and onions, leeks do not form bulbs underground. Instead, leeks grow an edible stem that can be up to 2 inches in diameter. Like garlic, the leaves are flat (onion leaves are tubes). Leeks are commonly paired with potatoes, but they can also be steamed, roasted, or baked to stand on their own.
There are two basic types of leeks. Short-season leeks are planted in spring and harvested in late summer and early fall. Hardy long-season leeks are also planted in spring, in the north, but not until late summer in warmer areas. These leeks are not ready for harvesting for at least 100 days, which means they are ready for use through winter.
How to grow leeks
Leeks are biennial plants that are grown as annuals. You can start leeks from seed or by replanting the white base of an existing leek. If you use the base of a leek purchased from the grocery store, be aware that you may be introducing destructive pathogens into your garden.
The base should be planted much deeper than you might expect: 4 to 6" deep. This is how part of the stem stays white, because it is blanched underground. Blanching means keeping certain parts of a plant white by blocking sunlight.
If you use seeds, plant them 1/2" deep and 6" apart. If you start seeds indoors, be sure to harden them off before planting them in the ground or in tall containers outside. You can also buy seedlings from your local garden store, but they will need to be gently untangled from each other before replanting - they look like unmown grass in the pot. Seedlings should then be transplanted deeper into the soil than they were, up to where the green stems begin, for a longer, more drought resistant edible. Once the seedlings are as big around as a pencil, bank soil or mulch around each plant to continue blanching the base.
Leeks prefer cooler temperatures, so fall and winter are the best time to grow leeks in areas with hot summers. Leeks enjoy full sun and well-drained soil, but the two components that make the biggest difference in growing leeks are water and nitrogen. Leeks are heavy feeders, so planting them near peas or beans will provide an extra boost of nitrogen early in the growing process, followed with aged compost. Leeks have shallow roots so regular watering is needed for plants to reach full size. Water stress will significantly reduce yields. The soil should be moistened to a depth of 18 inches every week. Mulching around plants can reduce weeds, add nutrients, and cut water needs.
Onion maggots, onion rust, aphids, thrips, and onion white rot are the most common problems encountered when growing leeks.
I ran across this word while researching soaker hoses, and was intrigued.
Parterre comes from 17th century French par terre, which means ‘on the ground’. A parterre is a level space within a garden or landscape that is dedicated to a formal artistic arrangement of flower beds. Most parterres feature gravel walkways and tiny hedges.
Knot gardens are one type of parterre. Knot gardens are usually very formal arrangements of culinary herbs and aromatic plants that have been planted into the shape of various types of knots, within a square space.
Knot gardens were very popular during the 15th century Renaissance, becoming even more elaborate during the 17th century Baroque period. Simple knots evolved into intricate arabesques of plants with varying colors, textures, shapes, and sizes.
Plants commonly used in parterres include: thyme, lemon balm, chamomile, rosemary, violas, germander, hyssop, and Calendulas.
While most of us probably don’t have the time or the space to create these intricate designs, there’s no reason why we can’t enjoy looking at images of parterres around the world and draw inspiration for our own gardens.
I would love to see some before and after photos, if any of you have tried your hand at parterres in your landscape!
Germander is a rugged, woody, fragrant variety of plant from the mint family.
If you are looking for a handsome, drought tolerant plant that can grow in pretty much any soil, consider germander. Full sun, partial sun, clay soil - germander doesn’t seem to care. And the deer leave it alone!
Germander actually refers to an entire genus of plants called Teucrium. These plants are from the Mediterranean and eastern Europe. They grow wild in poor, rocky soil, so our California clay and drought are no problem.
There are several varieties of germander to choose from:
Germanders of all types feature sturdy pale green to grayish-green to foliage. These evergreens can have tiny flowers, like rosemary, or flowers on spikes. The leaves of some varieties can be very aromatic when crushed or brushed against. The color, structure, and fragrance have made germaders a popular choice for formal knot gardens and parterres. Their low maintenance durability make them excellent border plants, ground covers, and landscape anchors.
Butterflies, bees, and other pollinators love germander flowers for their pollen and nectar. Germander can be grown in containers, indoors or out. Most germander varieties tend to get leggy, so pinching off or cutting stems just above leaf intersections can promote a bushier growth. Germander’s characteristics make it useful in many ways:
How to grow germander
As a member of the mint family, germander is easiest to grow from cuttings and division. You can simply pull a piece of existing plant from the ground and put it in some moist soil. New roots should be visible before long. You can also snip a stem and treat it the same way. If you grow germander from seed, it may take a month for them to germinate. I don’t know about you, but a seed that takes that long to break ground is often forgotten about - especially if I forgot to use a plant marker. Take a look at germander the next time you visit a garden supply store. They normally have several varieties available. Germander pests include mites, rust, powdery mildew, and leaf spot, but healthy plants are generally able to fend for themselves.
Do you have room for germander in your garden? I'd love to see photos!
Parsley - it’s not just for restaurants any more.
As a kid, I always turned a suspicious eye toward that sprig of greenery on my plate. My mother urged me to try it, so I did. Unfortunately, my young taste buds were not impressed. The mildly bitter bite of parsley was not my idea of delicious until many years later. Now that my taste buds are older and wiser, the refreshing tang of parsley adds a bright balance between flavors, cleanses the palette, and spices things up. If that weren’t reason enough to add parsley to a landscape, parsley packs one heck of a nutritional punch and, hey, it looks nice in the garden!
Parsley is a central Mediterranean plant, which means that it grows well in California, as long as it is protected from our scorching hot summers. Parsley makes an excellent shade garden or container plant. You can even grow it on your kitchen window sill for easy access and nice color if you have strong enough sunlight.
Parsley is related to celeriac and celery, which explains its Latin name (Petroselinum crispum), which means ‘rock celery’, but it’s a heck of a lot easier to grow than celery. Parsley prefers well-drained soil that is kept moist, but my plants seem to grow under just about any conditions. In spite of my heavy clay soil, I have several parsley plants that thrive under roses, trees, and shrubs. Research has shown that parsley also repels asparagus beetles, making it a good companion to asparagus and tomato plants.
Growing parsley does require some patience if you are starting from seed. Seeds should be planted 1/2 inch deep, 6 inches apart, and they can take 4 to 6 weeks to germinate. Germination rates are pretty high, so growing parsley from seed is the most cost effective method. While you’re at it, plant some extras and give young plants to family and friends as gifts!
In tropical areas, flat-leafed and curly parsley are grown as annual herbs. In more temperate regions like ours, parsley is biennial. Biennial plants take two years to go from seed to seed, but some of my parsley plants keep on growing for another year or so. In addition to leaf parsley, there is a variety called Hamburg root parsley (P. crispum radicosum). Root parsley is grown for the taproot, which looks, cooks, and eats like a white carrot. (I may have to try that!)
Parsley plants allowed to go to seed provide habitat, pollen, and nectar to honey bees and many other beneficial insets, some swallowtail butterflies, and even goldfinches.You will probably also end up with many free, randomly placed parsley plants next year!
If flavor and looks weren’t reason enough to grow your own parsley, the CDC says it’s a nutritional gold mine. They ranked parsley at #8 as a food that reduces chronic diseases, such as cancer, coronary disease, and osteoporosis. To learn more, check out the U.S. Dept. of Agriculture’s nutritional analysis website that allows you to look up the nutritional value of pretty much any food. Just 10 sprigs of parsley provides 22% of the RDA for Vitamin C and 200% of Vitamin K.
It’s pretty. It’s durable. It’s good for you. And it tastes good.
Where’s your parsley planted?
While walking across Spain in 2016, I came upon an albergue (something like a hostel) where someone was using a riding mower. There wasn’t any grass, but the air was filled with a sweet, powerfully refreshing smell. Rather than caring for a lawn, this family had a yard filled with mint!
Now, mint is an amazing plant. It is crazy invasive and comes in many varieties. We’ve all heard of spearmint and peppermint, but did you know there is a chocolate mint? I have one growing in a leaky, handmade, stone pond that came with our property. Visitors are always amazed when I urge them to chew on a leaf - instant peppermint patties! I have also learned that there are apple, pineapple, orange, banana, and ginger mints. Needless to say, I am intrigued!
Mint (Lamiaceae) is a huge family, with over 7,000 species. People have been using mint plants for, well, forever! Mint is cousin to a surprising number of familiar herbs and other plants: basil, oregano, thyme, rosemary, sage, bee balm, lemon balm, lavender, savory, and even your desktop coleus plant and the mighty teak tree! Lamb’s ears, hyssop, self-heal, catmint, salvia, horehound, chia, skullcap, wild bergamot, and bugleweed are also members of this clan.
Most members of the mint family have square stems, small flowers, opposite leaves, and volatile oils that make them taste and smell so wonderful. If you look at any of the mint family flowers up close, you will see that they each have four stamens and five petals that are fused together, with two petals pointing up and three petals pointing down. Most mint plants are perennial.
Mint is super easy to grow. They love the sun, but can handle partial shade, and are drought tolerant. That being said, I find my chocolate mint plants, while nearly indestructible, prefer regular watering during the peak of our California summer. Because mint can be so invasive, you may want to try it for your own lawn replacement, or, for a more restrained planting, use mint in containers. I have found that mint is easiest to grow from cuttings. (If you live in the Bay Area, I am happy to share cuttings of my chocolate mint!). All you have to do is cover the cutting lightly with good soil and keep it moist until new roots start growing. Left to their own devices, mint plants will spread everywhere, using rhizomes, at or just below the soil surface. The real problem with mint is stopping it.
Mint juleps anyone?
Assassin bugs may not sound very friendly, but they can do your garden a world of good as they suck the blood from many plant pests.
Assassin bugs are a family of insect predators. They also take blood from mammals, but we'll get to that in a moment. The two most common assassin bugs are the leafhopper assassin bug (Zelus renardii) and the spines assassin bug (Sinea diadema). These long-legged beneficial insects are originally from the tropics.
Assassin bugs tend to be slender and colorful, with round, beady eyes. One feature that makes them easy to recognize (if you are foolish enough to get that close) is their needle-like beak with 3 segments. They use that beak to inject venom into their prey, often after laying in wait for the right moment. [These bugs belong in a sci-fi detective novel!]
The nymphs are frequently confused with leaf-footed bug nymphs. Both are slender and they tend to be pale brown, blackish, or red. The nymphs are only 1/4 inch long, so you may never see them. Adults can each 3/4 inch. You are more likely to see clusters of the brown, white-capped, barrel-shaped eggs on leaves and stems. The adults are clumsy fliers, but they are voracious feeders.
Assassin bugs will eat pretty much anything they can sink their beak into. They seem to prefer caterpillars, leafhoppers, and aphids, but they will also feed on other beneficial insects, such as lacewings, and blood from you and me!
Also known as Kissing Bugs, assassin bugs have been known to bite people, transmitting the microorganism that causes Chagas' disease. This usually only happens in rural central and south America, but, as with chickens, you should keep these critters away from your face.
We’ve all heard about fish emulsion, but what’s really in it and how does it actually work in the garden?
Proponents claim that fish emulsion is an excellent slow-release fertilizer, especially for delicate seedlings, providing a gentle dose of nitrogen. Fish emulsion is organic and nontoxic.
Some of the down sides of using fish emulsion are cost and smell. Let’s face it, dead fish have a pretty short half-life. The smell may also attract some unwanted wildlife, such as skunks and flies. Some fish emulsion manufacturers claim that their product is “non-odorous”. I can’t imagine how that happens, but maybe.
Now, most commercially available fertilizers range in significantly higher numbers than fish emulsion, when it comes to nutrients. If you recall, the NPK numbers found on fertilizer packaging refers to the percentage by weight of nitrogen, phosphorous, and potassium, respectively. Commonly, the nitrogen and potassium numbers will be in the double digits, while phosphorus is usually a single digit number. For fish emulsion, the numbers are much lower. The NPK ratio of fish emulsion ranges from 4-1-1 to 5-2-2. This is neither good nor bad, it simply shows that the nutritional value of fish emulsion is lower than many other sources of plant food.
The science behind fish emulsion studies has come to some specific conclusions:
So, the bottom line on fish emulsion: it is an effective way to feed delicate seedlings and transplants, providing easy to use nutrients, but it doesn’t do much of anything for larger, more mature plants.
In my book, I categorize fish emulsion as a plant baby food.
Have you used fish emulsion successfully? Let us know in the comments!
Blistered leaves and warty twigs are signs of eriophyid mites.
Eriophyid mites are a family of microscopic plant parasites that include blister mites, gall mites, bud mites, and rust mites. While you will probably never see them without a 20x hand lens, at 1/100” in length, they can be a translucent yellow, pink, white, or purple, with two pairs of legs up near the head.
Symptoms of eriophyid mite feeding include:
Blister mites commonly attack beech, boxelder, cottonwood, elm, maple, live oak, walnut, willow, poplar, roses, privet, and alder. Unfortunately, they also feed on tomatoes, peach, apples, pear, and grapes. I have also heard of them on plum trees in the Bay Area. Eriophyid mites spread on the wind, so there isn’t much you can do to stop them from showing up in your landscape. Luckily, the damage they cause is mostly aesthetic and poses no real threat to otherwise healthy plants. That being said, who wants warty leaves or scabby twigs? Also, eriophyid mites may also carry viruses that can cause real damage.
Insecticidal soaps and horticultural oils can be used on heavy infestations, but simply removing affected leaves, buds, flowers and twigs is really all that’s needed. Sulphur and neem oil have also been shown to be effective. Before you work too hard at getting rid of these minor pests, you may want to keep in mind that the eriophyid mite serves as a replacement food for predatory spider mites and other beneficials, when their foods of choice are absent.
Isn’t it nice to know that some problems in the garden are not big enough to worry about?
Poise and grace may carry us through difficult situations, but sometimes things just need to fall apart. Much like social disasters, there is far more going on in the garden than meets the eye when decomposition takes place.
Decomposition describes the way complex organic structures are broken down into simpler structures. When plants and animals die, all the processes that held them together and kept them functioning stop working and they become organic matter. The study of how things decompose is called taphonomy, from the Greek word for tomb.
Most of the mineral food enjoyed by your plants comes from organic matter that is breaking down the plants and animals that have died. You probably already knew that, but did you know that the living things that speed decomposition actually reduce the amount of nitrogen in your soil as they feed?
Basically, there are two ways decomposition occurs: with the help of other living things (biotic decomposition) or through physical or chemical processes (abiotic decomposition). Now, you may think that this doesn’t apply to you as a gardener, but what about your compost pile? What is all that mulch actually doing to your soil as it breaks down? It’s really pretty amazing, so read on!
There are three basic stages of decomposition:
This is why your compost pile works faster when you chop it up and flip it periodically. The cut edges provide points of entry for all those microscopic workers and the air helps the microbes breath. Warmer temperatures also speed up the process. Like us, those little helpers don’t move nearly as fast in winter! But, as they feed, they take the chemical elements that made up the plant and break them down into nutrients that are available to living plants.
So what happens when I put straw mulch around my fruit trees?
Air, sunlight, and water will add their two cents to the decomposition process, but straw is pretty tough, so it will take some time to decompose. Local birds may grab a few bits and the sowbugs are sure to start feeding, but it is the microbes who will do the lion’s share of the work.
The plants and microorganisms that feed on dead or decaying plant matter are called saprophytes. As the saprophytes feed, they poop out simple minerals that plants use and gummy substances that hold bits of soil together into aggregates. These aggregates improve soil structure by creating plenty of macropores and micropores. This means that water and nutrients will move through the soil more easily. These soil aggregates also improve aeration, drainage, water-holding capacity, and water infiltration rates.
As decomposition takes place, carbon dioxide is also released. This CO2 can end up in the atmosphere, or it may combine with water to form carbonic acid. Carbonic acid (H2CO3) works with other chemicals to break down rocks and pebbles in the soil, making those nutrients available to nearby plants.
What about the net loss of nitrogen?
It ends up that there is a delicate balance between the amount of nitrogen available to plants and the needs of the saprophytic bacteria and fungi that make those nutrients available. If you add a bunch of carbon (straw, leaves, kitchen scraps) to an area, the microbes will begin feeding and breeding like crazy. The only thing is, they also need nitrogen to live, so they will pull it from the soil, creating an initial nitrogen loss. Of course, over time, all of those nutrients will end up back in balance, supporting your garden, but that may take time that your seedlings simply do not have. This balancing act is called the carbon-to-nitrogen ratio.
Ideally, you will want a 10:1 to 12:1 ratio of carbon to nitrogen. This means adding one pound of nitrogen for every ten pounds of carbon. If you are going to add a large amount of carbon to an area, it is a good idea to also add nitrogen. This keeps all the inputs for your soil microbes in balance as they improve your soil. Personally, I sprinkle blood meal (a good source of nitrogen) over an area, top that with aged compost (a good slow-release of many different nutrients), and then mulch with straw. The mulch keeps down weeds, stabilizes soil temperature, and, combined with the compost and blood meal, provides excellent nutrients and improved soil structure. It’s my way of tucking in my plants for our mild winters or when plants are stressed by too much California sun.
If you have access to a microscope, check out the various stages of decomposition to see what’s really going on down there!
You can grow a surprising amount of food in your own yard. Ask me how!