Feeding Plants: Companion Planting
[Adapted from Carrots Love Tomatoes by Louise Riotte, Mother Earth News February/March 1992]
The A to Z Guide to Companion Planting for Healthier Plants and Bigger Harvests
The magic and mystery of companion planting has intrigued and fascinated men for centuries, yet it is a part of the gardening world that has never been fully explored. Plants that assist each other in growing well, that repel insects, or that even repel other plants are all of great practical use, but we're just beginning to find out why. In the years to come I hope scientists, gardeners, and farmers everywhere will work together to make discoveries that will prove of great value in augmenting the world's food supply. Already, companion planting has produced insect- and disease-resistant fruits, grains, and vegetables, and experiments are being conducted on weed-resistant varieties.
A major enemy of the carrot is the carrot fly, whereas the leek suffers from the leek moth and the onion fly. Yet when they live in companionship, the strong and strangely different smell of the partner plant repels the insects so well that they do not even attempt to lay their eggs on the neighbor plant. This is why mixed plantings give better insect control than a monoculture where many plants of the same type are planted together in row after row.
It's the same with kohlrabi and radishes in their community life with lettuce. Both are often afflicted by earth flies, but when the flies get the odor of lettuce they take off. Even when plants are affected by diseases one can usually alleviate the situation with a mixed plant culture.
All through this article you will find "what to grow with" and "what not to grow with." Both are equally important to gardening success. The following suggestions for companion planting are only a beginning. Your own experiments will lead you toward many different pathways and discoveries.
Asparagus (Asparagus officinalis). Parsley planted alongside asparagus gives added vigor to both. Asparagus also goes well with basil, which itself is a good companion for tomatoes. Tomatoes will protect asparagus against asparagus beetles because they contain a substance called solanine. But if asparagus beetles are present in great numbers, they will attract and be controlled by their natural predators, making spraying unnecessary. A chemical derived from asparagus juice also has been found effective on tomato plants as a killer of nematodes, including the root-knot sting, stubby root, and meadow varieties.
In my garden, I grow asparagus in a long row at one side. After the spears are harvested in early spring, I plant tomatoes on either side, and I find that both plants prosper from the association. Cultivating the tomatoes also stems weed growth around the asparagus. The asparagus fronds should not be cut much, if at all, until very late in the fall, as the roots need this top growth to enable them to make spears the following spring.
Bean (Phaselolus and Vicia). Many different kinds of beans have been developed, each with its own life of "good" and "bad" companions. Generally speaking, however, all will thrive when interplanted with carrots and cauliflower; carrots especially help the beans to grow. Beans also grow well with beets as well as cucumbers and cabbages.
A moderate quantity of beans planted with leek and celeriac will help all, but planted too thickly they have an inhibiting effect—causing poor growth for all three. Marigolds in bean rows help repel the Mexican bean beetle.
Planting summer savory with green beans improves their growth and flavor as well as deterring bean beetles. (It is also good to cook with beans.)
Beans are inhibited by any member of the onion family—garlic, shallots, or chives—and they also dislike being planted near gladiolus.
Broad beans are excellent companions to corn, climbing diligently up the corn stalks to reach the light. They not only anchor the corn more firmly, acting as a protection against the wind, but a heavy vine growth may also act as a deterrent to raccoons. In addition, beans provide the soil with nitrogen, which enriches corn growth.
Bean and Potato. Bush beans planted with potatoes protect them against the Colorado potato beetle. In return, the potatoes protect the bush beans from the Mexican bean beetle. It is considered best to plant the beans and potatoes in alternate rows.
Bean, Bush (Phaseolus vulgaris). Included with bush beans are those known as butter, green, snap, string, or wax. All will do well if planted with a moderate amount of Celery
(about one Celery
plant to every six or seven of beans).
Bush beans and cucumbers are mutually beneficial. Bush beans planted with straw berries also help one another, both advancing more rapidly than if planted alone.
One gardener believes that Celery
is benefited if grown in a circle so that the lacy, loosely interwoven roots make a more desirable home for earth-worms and soil microbes.
Bush beans will aid corn if planted in alternate rows. They grow well with summer savory but should never be planted near fennel. They also dislike onions, as do all beans.
Bean, Lima (Phaselous limensis). Nearby locust trees have a good effect on the growth of lima beans. Other plants give them little or no assistance in repelling insects. Never cultivate lima beans when they are wet, because if anthracnose is present, this will cause it to spread. If the ground has sufficient lime and phosphorous there will probably be little trouble from anthracnose and mildew.
Bean, Pole. Like others of the family, pole beans do well with corn and summer savory but they also have some pronounced dislikes, such as kohlrabi and sunflower. Beets do not grow well with them, but radishes and pole beans seem to derive mutual benefit.
Bee Balm (Monarda). Improves both the growth and flavor of tomatoes.
Beet (Beta vulgaris). Beets grow well near bush beans, onions, or kohlrabi but are "turned off by pole beans. Field mustard and charlock also inhibit the growth of beets. Lettuce and most members of the cabbage family are "friendly" to them.
Broccoli (Brassica oeraceae). Like all members of the cabbage family, broccoli does well with such aromatic plants as dill, celery, chamomile. sage. peppermint, rosemary, and with other vegetables such as potatoes, beets, and onions. Do not plant it with tomatoes, pole beans, or strawberries. Use pyrethrum against aphids but only before the flower buds open.
Cabbage (Brassicaceae). The cabbage family includes not only cabbage but cauliflower, kale, kohlrabi, broccoli, collards, and Brussels sprouts—even rutabagas and turnips. While each plant of this group has been developed in a special way, they are all pretty much subject to the same likes and dislikes, insects and diseases. Hyssop, thyme, Wormwood
, and southernwood are helpful in repelling the white cabbage butterfly.
All members of this family are greatly helped by aromatic plants, or those which have many blossoms, such as celery, dill, chamomile, sage, peppermint, rosemary, onions, and potatoes.
If rabbits dig in your cabbage patch, plant any member of the onion family alongside them. Or you can dust with ashes. powdered aloes, or cayenne pepper. Rabbits also shun dried blood or blood meal.
Butterflies themselves aren't harmful and can help pollinate plants. It is their hatched eggs which as caterpillars do such damage to the orchard and field crops. The white cabbage butterfly is perhaps the most destructive. Herbs will repel them: hyssop, peppermint, rosemary, sage, thyme, and southernwood.
Cabbages dislike strawberries, tomatoes, and pole beans. All members of the family are heavy feeders and should have plenty of compost or well-decomposed cow manure worked into the ground previous to planting. Mulching will help if the soil has a tendency to dry out in hot weather, and water should be given if necessary.
Cabbage and cauliflower are subject to clubroot. and if this occurs try planting in new soil in a different pan of the garden. Rotate cabbage crops every two years.
If cabbage or broccoli plants do not head up well, it is a sign that lime, phosphorus, or potash is needed. Boron deficiency may cause the heart of the cabbage to die out.
Celery (Apium graveolens). Celery grows well with leeks, tomatoes, cauliflower, and cabbage, while bush beans and celery seem to provide mutual assistance. One gardener believes that celery is particularly benefited if grown in a circle so that the lacy, loosely interwoven roots may make a more desirable home for earthworms and soil microbes. Celery and leeks both grow well when trenched. Both celery and celeriac are reported to have a hormone which has an effect similar to insulin, making them an excellent seasoning for diabetics or for anyone on a salt-reduced diet.
Corn (Zea mays). Sweet corn does well with potatoes, peas, beans, cucumbers, pumpkin, and squash. Research has shown that removing corn suckers is a waste of time as well as being detrimental to the development of the ears. Peas and beans help corn by restoring to the soil the nitrogen used up by the corn. Is there anyone who hasn't heard the story of Indians putting a fish in every corn hill?
MeMelons, squash, pumpkins, and cucumbers like the shade provided by corn. In turn they benefit the corn, protecting it from the depredations of raccoons, which do not like to travel through the thick vines. Similarly, pole beans may be planted with corn to climb on the stalks. But don't plant tomatoes near corn, because the tomato worm and corn earworm are identical.
Also of note: An experiment with odorless marigold showed that when it was planted next to corn the Japanese beetle did not chew off the corn silks.
Cucumber (Cucumis sativus). Cucumbers apparently are offensive to raccoons, so it's beneficial to plant it alongside corn. And corn seemingly protects the cucumbers against the virus that causes wilt. Thin strips of cucumber will repel ants.
Cucumbers also like beans, peas, radishes, and sunflowers, and—preferring some shade—they will grow well in young orchards. Sow two or three radishes, but let them grow as long as they will, even blossoming and going to seed. Cucumber beetles also may be trapped by filling shallow containers about three-quarters full of water into which some cooking oil has been poured.
If cucumbers are attacked by nematodes, try a Sugar
spray. I boil half a cup of Sugar
in two cups of water, stirring until completely dissolved. Let cool and dilute with a gallon of water. Strange as it seems, Sugar
kills nematodes by drying them out. This will also attract honeybees—insuring pollination and resulting in a bumper crop of cucumbers—so the spray is worth trying even if you don't suspect the presence of nematodes.
Cucumbers dislike potatoes, while potatoes grown near cucumbers are more likely to be affected by phytophthora blight, so keep the two apart.
Beneficial fungi are another enemy of nematodes. If you suspect their presence, build up the humus content of your soil. A chive spray is helpful for downy mildew on cucumbers as is a spray made of horsetail.
Cucumbers dislike potatoes, while potatoes grown near cucumbers are more likely to be affected by phytophthora blight, so keep the two apart. Cucumbers also have a dislike for aromatic herbs.
Plant scientists William Duke, of Cornell, and Alan Putnam, of Michigan State University, have discovered that certain cucumber varieties fight weeds by releasing a toxic substance. This natural process—allelopathy—is believed to be an inherited trait. Thus, attempts are being made to incorporate weed resistance into commercial crops much in the same way as insect and disease resistance is bred into plants.
Eggplant (Solanum melongena). Redroot pigweed makes eggplant more resistant to insect attack. During dry weather, mulching and irrigation will help prevent wilt disease. Dry cayenne pepper sprinkled on plants while still wet with dew will repel caterpillars. Eggplant growing among green beans will be protected from the Colorado potato beetle. The beetles like eggplant even more than potatoes, but they find the beans repellent.
Garlic (Allium sativum). Eldon L. Reeves and S. V. Amonkar, of the University of California, discovered garlic to be a powerful destroyer of mosquitoes, achieving a 100% mortality of five species of California mosquito larvae by spraying breeding ponds with a garlic-based oil.
Researcher David Greenstock, of the Henry Doubleday Research Association in England, found that a garlic-oil emulsion, used as an insecticide, killed 89% of aphids and 95% of onion flies.
Here's a recipe for a good garlic spray: Take 3 to 4 ounces
of chopped garlic bulbs and soak in 2 tablespoons of mineral oil for one day. Add a pint of water in which 1 teaspoon of fish emulsion has been dissolved. Stir well. Strain the liquid and store in a glass or china container, as it reacts with metals. Dilute this, starting with 1 part to 20 parts of water, and use as a spray against your worst insect pests. If sweet potatoes or other garden plants are attracting rabbits, try this spray. Rabbits dislike the smell of fish, too. Garlic sprays are useful in controlling late blight on tomatoes and potatoes.
Garlic grown in a circle around fruit trees is good against borers. It is beneficial to the growth of vetch, protects roses, and, when cloves are stored in grain, will repell grain weevils. All alliums, however, inhibit the growth of peas and beans. Plant garlic with tomatoes to protect against red spiders. I have done this for three successive years, with good results.
Kohlrabi (Brassicaceae). Kohlrabi grown with onion or beets, with aromatic plants, and, surprisingly, with cucumbers, are mutually beneficial in part because they occupy different soil strata. Kohlrabi dislikes strawberries, tomatoes, and pole beans but helps protect mustard family members.
Leek (Allium porrum). Leek is a heavy feeder and should be planted in soil well-fertilized with rotted manure. Leeks are usually sold in the grocery store (at least where I live) with the roots still attached. I once bought several bunches and planted them; they grew well and propagated, and I've had leeks ever since.
Leeks are good plants to grow with celery and onions, and also are benefited by carrots. Returning the favor, leeks repel carrot flies.
Lettuce: (Lactuca saliva) In spring I kep a supply of small lettuce plants growing in cold frames. When I pull every other green onion for table use I pop in lettuce plants. They will aid the onions, and the compost in the onion row will still be in good supply for the lettuce to feed on, while the onion will repel any rabbits.
Lettuce grows well with strawberries, cucumbers, and carrots, and it has long been considered good to team with radishes. Radishes grown with lettuce in summer are particularly succulent.
Okra (Hibiscus esculentus). This native of the Old-World tropics is grown for its immature pods, which are called okra or gumbo. It's a warm-weather plant which grows wherever melons or cucumbers thrive. I plant two rows, dig a trench between, and cover it with mulch. On the north side of my okra, I plant a row of sweet bell peppers and on the south side a row of eggplant. All are well mulched as the season advances. When the weather becomes dry in midsummer I lay the hose in the trench and flood it so that all three companions grow well.
Onion (Allium cepa). Onions and all members of the cabbage family get along well with each other. They also like beets, strawberries, tomatoes, lettuce, summer savory, and chamomile (sparsely), but do not like peas and beans.
Since onion maggots travel from plant to plant when set in a row, scatter your onion plants throughout the garden.
Toxic substances in the pigments of red and yellow onion skins appear to be associated with disease resistance. Russian biologist T. A. Tovstole found a water solution of onion skin—used as a spray three times daily at five-day intervals—gave an almost 100% mortality of hemitera, a parasite
attacking more than 100 different species of plants.
Parsley (Petroselinum hortense). Parsley mixed with carrot seed helps to repel carrot flies by its masking aroma. It protects roses against rose beetles. Planted with tomatoes or asparagus, parsley will give added vigor to both.
Poultry are sometimes turned loose at intervals in parsley patches where there are many parsley worms, which are the larvae of the black swallowtail butterfly.
Parsnip (Pastinuca sativa). The parsnip is of ancient culture, but remains a vegetable for the discerning palate. The parsnips have few insect enemies and suffer from few diseases, but both the foliage and roots make a safe insect spray. They are not injured by freezing and are often left in the ground over winter. The seeds germinate slowly and unevenly and should not be used if over a year old.
Pea (Pisum sativum). For large crops, inoculate pea and bean seed with Nitragen (or similar compound), which is a natural bacterial agent. It coats the seed, aiding the sprouting seedling. This enables the plant to more readily form nodules on the roots which convert nitrogen from the air into a compound the plant can use.
Peas grow well with carrots, turnips, radishes, cucumbers, corn, beans, and potatoes, as well as many aromatic herbs. They do not grow well with onions, garlic, and gladiolus.
Pumpkin (Cucurhita pepo). Pumpkins grow well when jimson weed, sometimes called thorn apple, is in the vicinity. Pumpkins grow well with corn (a practice followed by Native Americans), yet pumpkins and potatoes have an inhibiting effect on each other.
Radish (Rubus). If you grow both red and black raspberries, put a considerable distance between the two types. The reason for this is that the reds sometimes carry a disease which does little or no harm to themselves but may prove near fatal to the blacks. Do not grow raspberries and blackberries near each other, either. Potatoes are more susceptible to blight if grown near raspberries, many gardeners believe.
Spinach (Spinacia oleracea). Because of its saponin content, spinach is a useful pre-crop and does well planted with strawberries.
Squash (Curcubitaceae). Two or three icicle radishes planted in each hill will help prevent insects on squash and on cucumbers. Let the radishes grow and go to seed. Nasturtiums will repel squash bugs and so will cigarette ash and other tobacco residue if placed with the seed when it is planted. Squash planted either earlier or later than usual often will escape insect damage. I find fall-planted squash almost entirely insect-free.
Early in the day before the sun is strong, squash stinkbugs are sluggish, and in the small garden may be picked off. There are also insect-resistant strains of squash available.
Sweet Potato (Ipomea batalas). Nemagold sweet potatoes developed by the Oklahoma Experiment Station have built-in resistance to nematodes. Sweet potatoes generally have high-energy value, with only peas and beans yielding more. They have a common enemy—the fungus disease or wilt called "stem rot"—which can be controlled with disease-free seed and by rotating the crop. White hellebore controls a number of leaf-eating insects.
If rabbits bother your sweet-potato patch, spray with a diluted fish emulsion.
Tomato (Lycopersicon esculentum). Tomatoes will protect asparagus against the asparagus beetle. Since they are tender plants, put tomatoes in during late spring after the early crop of asparagus spears has been harvested. Tomatoes and all members of the Brassica family repel each other and should be kept apart. Tomatoes protect gooseberries against insects.
Tomatoes are compatible with chives, onion, parsley, marigold, nasturtium, and carrot, and for several years I have planted garlic bulbs between my tomato plants to protect them from red spider mites. Though not containing fungicidal elements, tomatoes will protect roses against black spot.
The active principle of tomato leaves is solanine, a volatile alkaloid that at one time was used as an agricultural insecticide. You can create your own insect-repellent spray for roses by making a solution of tomato leaves in your vegetable juicer—add 4 or 5 pints of water and 1 tablespoon of cornstarch. Strain and spray on roses where it is not convenient to plant tomatoes as companions. Keep any unused spray refrigerated.
Unlike most other vegetables, tomatoes prefer to grow in the same place year after year, and this is all right unless you have a disease problem, in which case plant your tomatoes in a new area. Stinging nettle growing nearby improves their keeping qualities, and redroot pigweed, in small quantities, is beneficial, too. Tomatoes are inhibited by the presence of kohlrabi and fennel.
Root excretions of tomatoes have an inhibiting effect on young apricot trees. Don't plant tomatoes near corn, since the tomato fruitworm is identical to the corn earworm. Don't plant near potatoes, either, since tomatoes render them more susceptible to potato blight.
If you smoke, be sure to wash your hands thoroughly before you work in your garden, for tomatoes are susceptible to diseases transmitted through tobacco.
Turnip/Rutabaga (Brassica rapa and Brassica napobrassica). An accident revealed that hairy vetch and turnips are excellent companions. Turnip seeds became mixed with the vetch a gardener planted, and they came up as volunteer plants. He found the turnip greens completely free of the aphids which usually infest them, apparently because the vetch provided shelter for ladybugs, which feast on aphids. Elsewhere it has been found that wood ashes around the base of turnip plants will control scab.
I find peas planted near turnips are mutually benefited. Turnip and radish seed mixed with clover will bolster the nitrogen content of the soil. In your crop rotation it is good to follow the heavy feeders with light feeders such as turnips and rutabagas.
Turnips dislike hedge mustard and knotweed, and should not be rotated with other members of the cabbage family such as broccoli or kohlrabi. When synthesized, a naturally occuring chemical compound in turnips when synthesized is deadly to aphids, spider mites, houseflies, German cockroaches, and bean beetles.
Rutabagas take much the same culture as turnips but require a longer growing season.
Feeding Plants: Watering
[Adapted from Watering the Garden by Susan Glaese, Mother Earth News July/August 1986]
Here's how to get a sometimes confusing job done as efficiently (and effectively) as possible.
Most of us—with the twist of a spigot—can turn a garden hose into an umbilical cord linking us to vast (yet not inexhaustible) underground rivers. And since many of us don't need to worry about the availability of water, being blessed with adequate supplies, we can often afford, instead, to fret about when to water … how much moisture to put down … implements and techniques are most appropriate to use … and how to conserve as much water as possible while still nurturing the crops.
SOIL AND WATER
Water provides more than just liquid to a plant; it's also the medium that enables nutrients and minerals to enter the roots. (Roots don't digest dirt—they're not "woody earthworms"—but instead obtain their nutrients only in solution.) What's more, through the process of photosynthesis, some of water's hydrogen is split off to become a constituent of the carbohydrate compounds that make up most of the body tissue of growing plants.
Interestingly, water also enables plant roots to obtain nutrients that are beyond their physical reach. At varying depths below our feet lies the water table. Above that is soil containing minute, air-filled vestibules. When enough moisture surrounds each soil particle to create a continuous film from roots to water table, plants can, by capillary action, draw water and thus food from places far beneath their roots. (When this happens, the soil is said to have reached field capacity.)
If, on hot summer days, the crops use more water than is replaced, dry air spaces are created within the soil, and the bridge to the water table is broken. Conversely, if a real downpour hits and the air spaces become flooded to the point of excluding oxygen altogether, plants can literally drown—because roots must have air available, as well as water.
Whether or not your garden soil will retain water well without becoming oversaturated is determined, for the most part, by its structure. But don't feel that you must live with the type of soil that's currently in your plot. The great equalizer, compost, can help improve any ground that has trouble properly absorbing or retaining water.
Take sandy soils, for instance. They often have large spaces between their particles that allow for excellent drainage—if there is existing moisture in the soil. If, however, as might be the case in an extremely sandy soil, those spaces are completely filled with air, they can actually become a barrier to water penetration. Rain will be able to penetrate no deeper than the first few inches, so even though the garden has gotten a good soaking, deeper levels will remain bone-dry. When that happens, plant roots tend to seek out only the upper few inches
of soil and will thus be quite susceptible to heat and moisture loss.
Compost added to such a sandy soil will act as a moisture-retaining wick. It should be incorporated deeply—say, six to eight inches—so it will also help attract roots downward.
Silty soil acts in much the same way. Its powdery, flourlike texture can let water slip right through . . . just as the soil itself would sift through your open fingers. In the process, that water will quickly leach nutrients from your plants. Here again, compost will give your plot a better waterretaining capacity.
Clay soils have another problem: They have so few air spaces that they're too easily flooded by water. A sticky, slimy, wet clay soil can easily drown roots. The addition of as much organic matter as possible is a definite must in order to lighten the soil to allow plant roots more room to breathe. At the Eco-Village, we turn in at least an inch
of compost (and preferably more) before planting any crop in our clay-heavy beds.
Turning under green manure (or cover) crops is often another good way to add more humus to the soil. Our own clay plot, however, doesn't have sufficient belowground air to stimulate the needed decomposition of turned-under crops, so we actually cut down most of the green matter and compost it before working it in.
On the other hand, adding sand to clayey soil is not supposed to help its texture—the clay allegedly "swallows" it up! As an old gardening maxim puts it: Put clay in sand, money in the hand; put sand in clay, throw money away. But when we finally tested this adage last summer by working about an inch
of sharp creek sand into a few beds along with their compost allotment, the sand did make a noticeable improvement in both texture and drainage.
WHEN TO WATER
Early mornings and evenings are almost magical times in every garden. The low rays of the sun impart a certain aura to leaves and fruit that's lacking in the harsh light and heat of midday. And, as chance would have it, those are also the best times of day to water.
Here at the Eco-Village, we water our established beds a few hours before dusk, when the day's work is behind us and the tranquility of early evening is descending. The soil, heated throughout the day, will warm the water as it percolates downward, making the liquid less chilling (and stressful) to the plants. Furthermore, watering in the early evening allows time for the foliage to dry before nightfall—preventing the sustained dampness that favors the spread of fungi and mildews. In addition, plants do much of their actual growing at night (employing the stored products of photosynthesis), so they can well use a late-day boost to their aqueous reserves. And evening is generally a time of reduced wind and cooler temperatures—so water added then will be less likely to evaporate (an important conservation consideration).
Of course, if you find that you spend most of your time in the garden during morning hours, you can water then instead. While doing so may not provide quite as many advantages as does early-evening watering, at least it avoids the hazards of adding water in the heat of the day (which can seriously stress plants) or at nightfall (which encourages disease). It also provides the earth with a deep, long drink early on that can help bring your plants through the coming hot afternoon.
Do remember one thing, though: It's never a good idea to work in your garden when the plants are wet (whether from rainfall or overhead watering). You can easily damage crops at such a time or—worse—spread disease. (Carrots, tomatoes, beans, and squash are especially vulnerable to handspread disease.)
HOW OFTEN AND HOW MUCH
Just as you may choose between two generally preferred times to water, there are also two schools of thought on how often to water. Daily light watering regularly replenishes the water that growth and evaporation use up. This way, the soil's water "arteries" remain intact and reach deep into the ground. And occasional deep watering accomplishes the same goal by periodically drenching the soil thoroughly.
Choose whichever technique you prefer—just DON'T go with occasional light watering. Such half hearted efforts will keep only the top inch
or two of soil moist . . . coaxing roots to grow only near the surface; where they can readily dry out.
To make sure you're watering enough—whether you go for the daily-light or the occasional-deep method—get a trowel, a soil tube, or an auger, and after you've watered, dig down about a foot to see just how deep your added moisture is penetrating. This is a very important learning step. With time, you'll develop a feel for how to keep the soil at its optimum saturation level. But until you gain such expertise, digging to see what's really happening underground is the way to go (and learn).
The first time or two you check, you may well discover that you've been watering too shallowly. Many people make that mistake, failing to realize that it can take three-quarters of an hour to fully water one 10' X 10' plot! Indeed, the average garden needs about one inch of rain or irrigation per week . . . which figures out to about 62 gallons per 100 square feet. If you provide that much in one weekly watering, it should soak the ground to a depth of about one foot. (Dig and see!)
Of course, most times, natural rainfall will provide some of that moisture, and you'll only have to make up the difference. You can estimate the amount of natural precipitation you've received by following your local weather reports, by putting a large can in the garden and measuring how deep the water in it is after each rain, or—if you like precision—by making your own rain gauge from a funnel and cylindrical tube. For the last method, use a funnel with steep sides, and set it where it's not exposed to ground splashings or heavy winds (about a foot off the ground is good). You can also add a thin film of oil to the cylinder to reduce evaporation losses. To determine the number of inches
of rainwater in the cylinder that will equal one inch of rainfall, divide the squared radius of the funnel by the squared radius of the cylinder. Thus, if your funnel has a three-inch radius and your collecting tube a one-inch radius, every nine (33 = 12) inches
of water collected in the cylinder will equal one inch of rainfall.
What about droopy leaves? Won't they tell you that you need to water? Well, not necessarily. Plants often wilt some on a hot summer day as a way of shutting down their systems to conserve moisture. If you water at that time, you can shock the flowers and vegetables and cause more harm than good. (In fact, if you overhead-water on such occasions, the plants may actually lose moisture; the leaves will give up internal liquid to try to balance the perceived atmospheric humidity and end up worse off.)
Instead, look for signs of wilting during morning and evening hours. If the leaves are drooping then, it's almost a sure sign that your plants need water—and fast! (One exception: Plants can also wilt if their roots are so wet that they're flooded. A quick trowel-in-the-dirt will determine the true cause if you have any doubts.) Remember, though, that some waxy-leaved plants, such as cabbage, onions, and garlic, don't show water stress as clearly as others. On the other hand, peas, celery, spinach, and lettuce are very susceptible to drought conditions and will let you know in no uncertain terms!
A quality garden hose is the heart of any watering system. A hose that will resist its inborn urge to kink and cut off flow is all but priceless. So don't skimp on this purchase—you'll never regret it. Standard diameters are 1/2", 5/8", and 3/4". The larger the diameter, of course, the greater the flow. (By the way, if you garden with raised beds, you can set rebar posts—with bamboo or PVC collars—at the corners of your growing areas . . . and the posts will conveniently steer your hose around the beds!)
A watering wand is a hose attachment that consists of along tube with a rose nozzle at the end. It's kind to your back, allowing you to stand upright while gently but thoroughly soaking the soil at ground level. The wand is just the thing for ground-watering melons, squashes, tomatoes, and other plants susceptible to leaf molds and fungi. It's also an efficient water user, since it places the liquid right where you want it, rather than spraying it all through the air and garden. We use ours frequently.
There are other common hose attachments for hand-held watering, including the fireman-type nozzle, the spray gun, and fan sprayers. All of these can be useful, but you do have to stand there and hold them . . . which takes time and increases the likelihood that you may skimp on watering. To make your operation a bit more automated, use a rotary or oscillating sprinkler. (The latter is generally easier to use, since most of us lay out our gardens in rectangularnot circular-patterns.) Sprinklers won't apply water entirely evenly, however, and they need to be moved periodically to prevent spot-flooding and runoff problems. (You can buy automatic timers to shut them off after specified periods.)
Sprinklers have other drawbacks. They waste a lot of water, both by evaporative loss and by wetting pathways—and weeds—as much as crops. They can increase salt buildup in your soil or on your plants (do your crops' leaves have a powdery residue on them or a burned-edge look?). And they wet the leaves of your disease-susceptible crops.
The most water-efficient, automated system around is drip irrigation—invented when an Israeli engineer by the name of Symcha Blass spotted the beneficial effects of a leaky spigot on the growth of a nearby tree. Drip irrigation systems today come in two types: plastic hoses with small valves—called emitters—spaced every couple of feet, and microporous plastic pipes that weep liquid along their entire length. Both systems use from one-third to one-half less water than do overhead watering methods . . . put the liquid right at your crops' roots . . . and help increase yields by reducing the stress of extreme fluctuations in moisture levels. Indeed, tests at Ohio State University have shown that peppers and cantaloupes grown with drip irrigation and black plastic mulch produced more than twice the yield of those grown without those two aids.
Drip systems do have some possible drawbacks. Their openings can clog (to avoid that, put an appropriate filter in your waterline). They can start to break down after prolonged exposure to sunlight (that won't happen if you keep the line just underground). And they must be moved whenever you're going to do any serious cultivation.
Their biggest disadvantage, at least for people with larger gardens, is cost . . . around $15 to $30 per hundred feet of tubing. Perhaps the best way to deal with that consideration is to buy a small "starter" drip system and try it out for a season so you can evaluate its effectiveness. Indeed, we intend to assess the merits of a number of such systems this summer at the Eco-Village. We'll tell you what we find out! [EDITOR'S NOTE: And we did! Our article "Ooze Who in Drip Irrigation"—just last issue—compared six beginning drip kits.]
Many times, conserving water will be as important as getting some to your crops. Particularly during July or August dry spells, you'll want to make sure your garden uses and loses as little water as possible.
In a row garden, one of the easiest ways to cut water demand is to plant three to five rows close together and thereby reduce wasted (and watered) pathway space. Of course, gardening in raised beds will save even more space. Since such beds incorporate a greater depth of loosened soil, they also absorb water better than row plantings do. In addition, raised-bed gardening frequently incorporates the art of spacing plants so that their mature leaves just touch—thus creating a "living mulch" that further blocks evaporation and conserves moisture.
Combine raised beds, living mulch, and double-digging (to loosen the soil as deep as possible), and you'll have a highly efficient water-conserving garden: John Jeavons' Ecology Action group in Willitts, California, has obtained excellent yields of vegetables using these biodynamic/French intensive techniques and one-eighth the water of conventional gardening!
While you obviously want to establish your garden away from the drip line of trees (their roots practically inhale water), those large plants do have their place as windbreaks. Much more water is lost to evaporation from wind than most of us realize. So you'd do well to utilize any available trees, houses, hedges, or fences to slow down the drying effects of hot summer breezes.
Mulching with dry materials such as hay, straw, wood chips, or even black-and-white newspaper pages most definitely helps protect bare soil from evaporative water loss. Keep in mind, though, that you shouldn't mulch too early in the growing year, or the covering will retard the warming of your soil. Also, carbon-laden mulches do tie up nitrogen while they're decomposing, so you should be sure that heavily mulched soil has ample nitrogen. (Fish emulsion, blood meal, cottonseed meal, and well-aged manure are some good nitrogen supplements.)
THE FUNDAMENTAL POINT
Finally, always remember that while expensive irrigation systems or conservation strategies will help you save water, the most significant way to conserve moisture is to make soil improvement your top priority. A humus-rich soil—created by using lots of compost and cover crops—will hold the water it gets while still allowing for aeration. Indeed, the soil should be our first concern in all aspects of farming and gardening, because nurturing the diverse life it sustains is the strongest step we can take toward growing healthy plants.
A Few Water-Saving Tricks:
There are plenty of small-scale steps you can take to make efficient use of garden water. Here are four no-cost tricks you might try:
Don't stake plants. Let your tomatoes, beans, and other climbers sprawl (on clean, dry mulch), or else grow bush varieties. By doing so, you'll expose less leaf area to the drying effects of sun and wind.
Grow some vegetables in partly shaded areas. Lettuce, parsley, peas, cabbages, and broccoli—among others—can do quite well on just five hours of direct summer sunlight a day. Fine netting shades crops well.
Punch small holes in the bottoms of large cans or plastic milk jugs, set the containers next to thirsty plants, and then fill them with water.
Hill up the sides of raised beds to create basins that will trap and hold as much rainwater as possible.
Organic Gardening: Pest and Disease Control
[Adapted from Carrots Love Tomatoes by Louise Riotte, Mother Earth News February/March 1992]
CONTROL OF INSECTS BY COMPANION PLANTING
Legumes planted in a rotation will protect grain crops and grasses from white grubs and corn rootworm. Chinch bugs on corn and flea beetles are controlled by growing soybeans to shade bases of the plants. Goats with worms may be relieved by feeding them carrots; in horses by feeding them mulberry leaves.
The following herbs may be planted as specific control:
BASIL: Against flies and mosquitoes.
BORAGE: Against tomato worm.
CASTOR BEAN: Against moles and plant lice.
CATNIP: Against flea beetles.
DATURA: Against Japanese beetles.
DEAD NETTLE: Against potato bugs.
FLAX: Against potato bugs.
GARLIC: Against Japanese beetle, aphis, weevils, fruit tree borers, spider mites.
HENBIT: General insect repellent.
HORSERADISH: Against potato bugs (plant at comers of plot).
HYSSOP: Against cabbage moth.
LAVENDER: Against clothes moths (dry and place in garments).
MARIGOLDS: Against Mexican bean beetles, nematodes and many other insects.
MINT: Against white cabbage moths, dried against clothes moths.
MOLE PLANT: Against moles and mice (Mole plant is a species of Euphorbia).
NASTURTIUM: Against aphids, squash bugs striped pumkin beetles, woolly aphids.
PENNYROYAL: Against ants an plant lice.
PEPPERMINT: Against white cabbage butterflies, ants.
PETUNIA: Against beetles.
POT MARIGOLD: Against pickle-worms, aphids, leafhoppers, spider mites, harlequin bugs, imported cabbage worms and many other insects.
PYRETHURM: Against pickleworms, aphids, leafhoppers, spider mites, harlequin bugs, imported cabbage worms and ticks.
ROSE GERANIUM: Oil or crushed leaves as insect repellants.
ROSEMARY: Against cabbage moths, bean beetles, carrot flies, malaria mosquitoes.
RUE: Against Japanese beetles.
SAGE: Against cabbage moths, carrot flies, ticks.
SANTOLINA: Against moths.
SASSAFRAS: Against plant lice.
SOUTHERNWOOD: Against cabbage moths, malaria mosquitoes.
SPEARMINT: Against ants, aphids
STINGING NETTLE: Against aphids, black flies.
SUMMER SAVORY: Against bean beetles.
TANSY: Against flying insects, Japanese beetles, striped cucumber beetles, squash bugs, and ants.
THYME: Against cabbage worms.
WHITE GERANIUM: Against Japanese beetles.
WORMWOOD: Against animal intruders, cabbage worm butterflies, black flea beetles, and even malaria mosquitoes.
DISEASE-AND WEATHER-RESISTANT VEGETABLE VARIETIES
ASPARAGUS: Mary Washington, rustresistant (Farmers).
BEAN: Topcrop, Tendercrop, Harvester, mosaic-resistant (Twilley Seed Co.). Wade, mosaic- and powdery mildew-resistant (Farmers).
BEAN, DRY SHELL: Michlite, blight-resistant (Farmers).
CABBAGE: Stonehead Hybrid, yellows-resistant (Burpee). Wisconsin Hollander No. 8; Copenhagen; New Wisconsin Ball-head, Wisconsin All Season, yellows-resistant (Shumway).
CUCUMBER: Marketmore. scab- and mosaic-resistant. Polaris, anthracnose-, downy mildew- and powdery mildew-resistant (Twilley). Burpees Hybrid, Total Marketer, downy- and powdery mildew—resistant (Shumway). Park's Comanche and Poinsett, downy- and powdery mildew—resistant (Parks). Salty, resistant to cucumber mosaic, powdery mildew, and scab (Nichols).
EGGPLANT: Faribo Hybrid, disease-resistant (Farmers).
KALE: Dwarf Blue Curled Vales, withstands below-freezing temperatures (Burpee).
LETTUCE: Oakleaf, hot weather—resistant. Butter King, Bibb, or Limestone, hot weather—tolerant (Shumway). Premier Great Lakes, resistant to tip-bum and heat (Burpee).
PEAS: Early Alaska, wilt-resistant. American Wonder, drought-resistant (Henry Fields). Drought-Proof (Burgess)
PEPPER: Yolo Wonder, tobacco mosaic—resistant (Gumey's).
RADISH: Cherry Belle, pithiness-resistant (Shumway).
SPINACH: Hybrid No. 7, resistant to downy mildew (Burpee).
SWEET CORN: Golden Beauty, disease-resistant. Silver Queen, disease-tolerant (Parks).
TOMATOES: VF Tomato, verticillium and fusarium wilt—resistant; Sunray, fusarium wilt—resistant (Burpee). Sunset, Starfire, sunscald-resistant; Monte Carlo, multiple disease-resistant (Farmers). Crack-Proof (Burgess).
TURNIP: Tokyo Cross, virus and other disease-resistant (Burpee).
This by no means exhausts the lists of disease-resistant vegetables, and more are constantly being developed. It helps to note the resistant strains when you check your seed catalogs. Many of the varieties listed here also are sold by other seed companies.
[Adapted from Guide to Organic Pesticides by Doc and Katy Abraham, Mother Earth News February/March 1994]
Effective and nontoxic products to zap pesky bugs.
The philosophy behind organic gardening is hardly new to MOTHER readers, who've known about the benefits for years. However, interest has grown markedly in the mainstream. Many are finally joining the organic movement in order to rebel against additives
in food, chemicals in the soil and water, pollutants in the air, and the dangerous pesticides regularly sprayed. The balance of nature has been precariously disturbed as the number of good and necessary bugs has been diminished, and to make matters worse, many of the harmful insects have developed resistance to common pesticides. But there's good news...
Today's scientists are discovering more and more plants that produce natural bactericides, fungicides, and insecticides. In fact, many nontoxic household products are considered effective in the war against gardening pests. Below are the acceptable organic controls that gardeners find most effective today.
Household detergents: Mix these insecticides right in your kitchen.
1) USDA recommendation: Mix one teaspoon of liquid dishwashing detergent with one cup of vegetable oil. Shake vigorously to emulsify and add to a quart
of tap water. Use at 10-day intervals as an all-purpose spray for white flies, spider mites, aphids, and various insects on carrots, celery, cucumbers, eggplants, peppers, and others. We've used it on evergreens and other ornamentals. Note: Test on a single plant first, because it may cause tip burn. This is a contact insecticide, so spray mix directly on the pest.
2) Liquid detergent-alcohol spray:
Mix one teaspoon of liquid dishwashing detergent plus one cup of rubbing alcohol in one quart
of water. Test on a few leaves first to make sure no harm is done to sensitive plants. Spray top and bottom sides of leaves; or if plant is small and potted, invert it in a large pan of solution (holding soil ball securely) and gently swish back and forth. Repeat in seven days.
3) Liquid detergent—hot pepper spray:
Steep three tablespoons of dry, crushed hot pepper in 1/2 cup hot water (covered) for half an hour. Strain out the particles of peppers, and then mix solution with the liquid detergent formula mentioned above. Good for a number of insects on both indoor and outdoor plants. Note: Apply to plants outdoors. Do not use on windy days. Avoid breathing fumes, which can be irritating to nose and eyes. You can substitute hot Tabasco sauce or Louisiana hot sauce for hot pepper.
Pyrethrin: This natural insecticide derived from the pyrethrum plant (Chrysanthemum cinerariaefolium). Along with pyrethroid, its synthetic substitute, it is highly effective against a wide range of insects. Each should be used according to manufacturer's directions.
Lime sulfur: This old-timer, still used by both organic and nonorganic gardeners, is applied during the dormant period. Kills most species of mites as well as mite eggs and those of many other insects. Lime sulfur also has fungicidal value and can be used on fruit trees as well as ornamentals. Note: Lime sulfur applied to plants near the house will stain the paint. Apply cautiously near buildings.
Sabadilla: Made from seeds of a South American lily. Used for squash bugs and stink bugs. Irritating to eyes and lungs if care is not taken. Use according to manufacturer's directions.
Garlic and onions: Grind up raw onions or garlic into a puree. Soak in warm water overnight and strain. Liquid can be sprayed on roses, fruit trees, and flowers. Kills aphids and apple borers. Scrape off any loose bark on the trunk and swab liquid on. Many gardeners mix onion water and wood ashes and paste mixture on tree trunks.
Ryania: Made from ground stems and roots of a South American shrub. Controls European corn borer and other worms. See directions on container.
Tomato leaves, crushed: To avoid chemical sprays, try using crushed tomato leaves for leaf-spot diseases. Tomato leaves contain solanine, a chemical that has an inhibiting effect on black spot fungus. Grind two cups of leaves to a puree. Add five pints of water and one ounce of cornstarch. Keep refrigerated.
Tobacco water: Cigar and cigarette butts will kill worms in the soil of houseplants. Mix a solution of tobacco and water so that it is the color of brown tea; pour on the soil. Don't let anyone drink it by mistake! The solution kills fungus gnats, symphylids, centipedes, root lice, and other underground pests—and it could kill you.
If you have aphids or other insects in your terrarium or dish garden, ask a friend who smokes to blow cigarette smoke into the glass and then seal the top. The smoke knocks plant lice for a loop.
Snuff: For tiny flies or worms in the soil of house plants, try sprinkling snuff on the surface. Note. Do not use homemade tobacco remedies on tomatoes, peppers, eggplants, and other members of the Solanum family. It could spread tobacco virus to these plants.
Retenone: An old remedy for killing Mexican bean beetles. It is produced from derris, a plant found in Central and South America. Kills aphids, thrips, and chewing insects on contact. Note: Toxic to fish and nesting birds.
Hot pepper: To discourage cats, dogs, many insect pests, and snails from munching, dust powdered hot pepper or a spray of hot pepper sauce on plants.
Oil and sulfur sprays: Petroleum oils (of organic derivation) have been used successfully for killing insects for over 200 years. Apply only on "hard" or woody plants. There are two types:
1) Dormant oil should be used only when plants are dormant — in winter or early spring.
2) Summer oil should be used during the growing season and restricted to woody plants. Some oil sprays can be applied in either summer or winter.
Miscible oil sprays kill insects and eggs such as over-wintering leaf rollers and aphid and mite eggs. They also kill scale insects and adult mites. Dilute with water according to manufacturer's directions. The oils cause little or no harm to most beneficial insects, and resistance to sprays does not build up with oils.
Talcum powder: Effective against flea beetles and corn ear worm. Lightly dust leave surfaces after every rain.
Soaps as insecticides: Soapsuds are ideal for killing aphids. Many home gardeners prefer vegetable- or plant-based soaps as effective aphicides.
Rhubarb leaves: Boil one pound of chopped leaves in one quart
of water for 30 minutes. Strain and use as a spray against aphids and other pests.
Garlic and red-pepper spray: Grind up a large bulb of garlic (or a large onion). Add one tablespoon of ground cayenne pepper and one quart of water. Steep for one hour. Strain liquid into a sprayer or watering can and refrigerate remainder in a tightly covered jar. It will be potent for several weeks, and is effective on all kinds of chewing and sucking insects.
Spearmint spray: Put into a blender one cup of chopped spearmint leaves, one cup of green onion tops, and 1/2 cup of chopped hot-red pepper. Add 1/2 cup of water to assist in blending. Pour solution into a gallon of water. Add 1/2 cup of liquid detergent (preferably lemon-scented). Dilute by adding 1/2 cup of mixture to a quart of plain tap water.
If the plant is small, dunk it in this solution, otherwise strain it and spray on. Effective on all chewing insects.
[Adapted from The Green Thumb Garden Handbook, published by Lyons & Burford]
ORGANICALLY SPEAKING: The best reason to garden organically: clean, unsprayed, absolutely fresh fruits and vegetables that are picked only when they reach the perfect degree of ripeness.
A TO Z: TIME-SAVING TIPS, TRICKS, AND SHORTCUTS FOR GARDENERS
Apple Maggots On the Run
Here is a brew that will trap one of the worst enemies of your apple crop: the apple maggot. Mix one part molasses with nine parts water, then add yeast to produce fermentation. Pour this mixture into wide mouth jars and hang in nearby trees.
Chop banana peels and add into soil when you transplant tomatoes and green peppers. This will ensure very strong trunks and stems. Banana peels contain 3.25% phosphorus and 41.76% potash. They're also an excellent fertilizer for roses, but use sparingly; two or three peels per bush at a time is about right.
Carrots like to grow in loose, sandy soil and if you have clay soil you will find carrots very challenging. In Midwest Gardening, Denny McKeown offers an excellent solution: "Simply dig a trench 12" deep and the width of your shovel. Mix sand and peat humus with some of the existing soil (about 50/50), and backfill the trench. Then plant your carrot seeds."
Most active at night, daddy longlegs (also known as harvestman), prey on aphids, mites, leafhoppers, and other garden insects.
Not only do they add lime, nitrogen, and phosphorus to the soil, eggshells also help to foil cutworms when crushed and sprinkled around seedlings.
In the larval stage the firefly can be considered of material benefit to man. The growing juveniles eat animals that feed on the leaves. Their favorite foods are the small snails they share living quarters with in decaying wood and soil.
If you have a problem with gophers digging in your lawn try this: put two or three bulbs of garlic, several chili peppers, and some water in your blender and blend well. Pour this down some of the gopher holes and rinse with a strong stream of water from the hose.
Honeybees and Hay Fever
There's a theory that hay fever sufferers who eat honey produced within a few miles of their homes will find that it alleviates their misery. The pollen of the flowers and weeds, which the honeybee makes into honeycomb, is believed to provide a natural antitoxin.
Insects Can't Slip By
Some insects that damage fruit trees crawl from the soil to the branches to lay their eggs. They can be stopped by wrapping the trunk with six to eight inches of tape or grease-resistant paper and applying Vaseline or other grease to the tape. Don't put Vaseline directly on the tree-it may cause damage.
Japanese Black Pine
This beautiful pine grows somewhat irregularly. It is an excellent choice if you have a garden near a windy seashore because it is resistant to both wind and salt spray. I have also found it to be a good choice for dry, windy Oklahoma.
Unless pruned quite heavily, kiwi will become a tangled mass. Prune after the leaves drop. Removing the weaker canes will encourage the stronger ones to be more productive.
Shred leaves and mix with grass clippings to make a good mulch. It will decompose rapidly and give mulched plants the benefits of their many nutrients.
Mice sometimes completely girdle young fruit trees. Painting with standard tree wound paints is helpful. Or you might try covering the wounds with white corn syrup and then wrapping with aluminum foil.
To make newspaper mulch for vegetables: place several layers between plant rows, and keep them wet so they won't blow around. Also weigh them down with a few clods of earth. Weeds won't sprout underneath, and when the papers decompose, they enrich the soil.
The tiny screech owl--more often heard than seen-patrols moonlit yards for insects and mice. Lizards, salamanders, and worms may also scooped up during the owl's nightly forays. The barn owl is probably the most important predator of rats and mice in populated areas, rivaling the house cat in importance.
Painting the trunks of fruit trees with Tabasco sauce helps deter rabbits and mice.
Compost will break down and decay faster if the compost heap is placed in a shady location.
Red Spider Mites
These little peskies seem to appear suddenly, especially on tomato leaves, when really hot weather hits. Organic Plant Protection (Rodale Press) states: "A spray of two percent oil of coriander will kill the spider mite; a spray of anise oil should do as well." Frequent spraying with plain water will also help.
Sea Shell Mulch
Save those sea shells you collected at the beach and turn them into mulch. Face the cups of the shells upwards for those plants that need high humidity. Each time you water, the cups will fill with water and then evaporate into the air around the plant. Covering the top of the pot soil with small shells can also be very attractive.
The sooner excess fruit is removed after flowering, the more likely the remaining fruit will improve in size and quality. A good general rule of thumb for apricots, plums, apples, Asian pears, nectarines, and peaches is to thin them twice as far apart as the diameter you want them to be at maturity.
Umbels are the kind of blossom that a certain group of plants produces ("umbel" means umbrellalike in shape). These plants include carrots, parsley, coriander, dill, caraway, anise, fennel, angelica, and chervil.
Plant umbels in moist, rich soil where they will be able to enjoy much shade during the hot months of summer.
Vetches are used for hay, green manure, pasture crops, silage, and as a cover crop for orchards. They are also valuable for renewing soil fertility. Vetches require a cool growing season. The bacteria left in the soil from vetch roots serves as an inoculant and is beneficial to the growth of peas.
Watch for a Cloudy Day
Bright sun can hurt newly planted seedlings, so always try to transplant them during an overcast day in late afternoon or evening. Shading them the first day or two is also helpful if the sun comes out.
Plants especially adapted to withstand long periods of drought or to grow where supplies of water are scare are called xerophytes. Included among these plants are cacti and such succulents as aloes, cotyledons, crassulas, echeverias, haworthias, sedums, and sempervivums. Many of these store water in their fleshy leaves and stems.
Yarrow has long been acclaimed for its invaluable qualities in companion planting, adding strength to herbs and assisting in the battle against insect pests. Plant yarrow in the same beds with mint, chives, thyme, parsley, basil, oregano, or any other culinary or tea herb. Or plant it in your flower bed to add beauty and protection.
Zigging and Zagging
Togetherness is one way to practice companion planting — get the neighbors right in there next to each other. Plant zig-zag rows with onions and beets or carrots and tomatoes tucked into one another. Or use the techniques of intercropping by planting several companions in the same row, one of which might be a protective herb or flower.
Organic Gardening: Mulch
[Adapted from Priceless … and Free: Mulching a Vegetable Garden by Mort Mather, Mother Earth News June/July 1998]
Grass clippings are great mulch because they go where you want them... and stay there.
Mulch, as a verb, is the act of applying some covering to the soil, usually for the purpose of controlling weeds. As a noun, it is any material that will serve the purpose. If that sounds like a very broad range of materials, it is. I have used mulches that were living and dead and ranged from dust to oil. What they all accomplished—with any luck—was:
Controlling Weeds. I can't think of a mulch that doesn't do this if used properly. When I first heard of clear plastic being used as a mulch, I questioned how it would control weeds. After all, I used clear plastic to help plants that needed heat to grow. Clear plastic used as a mulch works to kill weeds by cooking them when the sun comes out. Some weeds may get started in cool cloudy weather, but one sunny day will shrivel them in a hurry. Unfortunately, I didn't learn this by using a clear plastic mulch. I learned it when, one sunny morning, I got to the garden a little late to open the plastic row covers over my eggplant and pepper seedlings. Baked seedlings were a sad lesson but one not soon forgotten. I paid for my laziness that year and didn't use plastic row covers for several years after that. Then I found slitted row covers which open up to release excess heat without my attention.
Retaining Moisture. All of the mulches I'm going to discuss retain moisture with the arguable exception of a living mulch. A living mulch like clover will draw moisture from the sod for its own growth and some of the moisture drawn by the plants will be lost to the atmosphere through the leaves. On the other hand, a carpet of leaves on low-growing plants that catches morning dew and holds a cushion of air beneath it may snake up for the moisture it uses. By cushion of air I mean that low-growing plants, such as clover grown between rows of corn, will shelter the soil surface from drying breezes and from the baking sun. Whether or not the beneficial influence offsets the moisture used is something for scientists to investigate.
All mulches, except dust, inhibit rainfall or irrigation from above from reaching the soil. For this reason, it is best to mulch a soil that is already moist. Here in New England, the spring soil is usually moist. There has been a time or two when I held back on mulching and waited for rain. Once an impervious mulch like plastic is put down, there is no chance of additional moisture reaching that soil in any quantity. It amazes me when I check the condition of soil under a plastic mulch in mid or late summer and find it moist below the top half inch.
Where are the plants getting sufficient water to fill out eggplant and tomatoes? The roots have probably extended beyond the plastic, but still, the soil under the plastic has received no additional moisture since the end of May.
Vine crops take up a lot of garden area in which weeds can flourish; just plant your mulch and forget it.
Fertilizing. All organic mulches do this. Grass clippings provide nutrients more quickly than other organic mulches. Sawdust is at the other end of the scale, as it will require nitrogen from a source outside itself to break down into usable nutrients and humus. When we put sawdust in contact with the soil, the sod organisms recognize a big job ahead and they multiply rapidly. To multiply, they need nitrogen. Since it is not available in the sawdust, they use nitrogen that is already in the soil. If the nitrogen supply in the soil is insufficient, the sawdust is converted more slowly. Of greater importance, the soil is deficient in nitrogen for the plants and they will suffer.
The most important thing to keep in mind regarding soil fertility and mulch is the carbon-nitrogen ratio. The carbon-nitrogen ratio of sawdust is 400:1, for example, while young sweet clover is 12:1. An average bale of hay might be 80:1, while rotted manure might be 20:1. A substance that has a C:N ratio below 17:1 will actually add nitrogen to the soil while a ratio above 33:1 will take nitrogen from the soil. Between those two figures the result is neutral. Grass clippings might have a ratio of 16:1 but if the plant is allowed to grow to maturity, the ratio might go to 30:1 or 40:1. If the plant starts to dry, the ratio goes up even more. Once dried as hay the ratio will be in the vicinity of 80:1.
There is one other factor to keep in mind regarding the C:N ratio. If the material is just going to be used as a mulch, the amount of interface with the soil is limited to the soil surface. It is when a high C:N ratio material is incorporated into the soil that the temporary loss of nitrogen can become severe. You may use a sawdust mulch on a section of the garden one year and have no problems. If you turn it under the next year, you want to stake sure to incorporate some additional nitrogen at the same time.
Materials from trees have the potential for lowering the pH of the soil—making it more acidic. Leaves, sawdust, and wood shavings are acidic. However, in the process of becoming humus, they move toward a higher pH. Also, it seems the more humus in the soil, the wider the band on the pH scale that is acceptable to plants. (See MOTHER x166 for more on sod fertility.)
Warming/Cooling the Soil. Clear or black plastic mulch will warm the soil more quickly in the spring and hold the warmth over