SUSTAINABLE ORGANIC GARDENING WITH COVER CROPS

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oats and field peas cover crop

Healthy, living soil is a vital component of an organic garden.  Soil covered with growing things draws carbon out of the atmosphere and stores it in roots, stems, and leaves.  In sustainable, earth-friendly gardening /farming we do not allow land to fallow, but keep our soil covered with actively growing or dormant plants all year.  This is a win-win situation for your garden; you can have abundant crops yet at the same time help reduce the amount of CO2 in earth’s atmosphere. 

Cover crops build and protect your soil by increasing humus and nutrients.  Cover crops will add organic matter, smother weeds, prevent erosion, break up  compacted soil, provide livestock forage and attract beneficial insects.  In dry summers or dry climates cover crops provide a kind of living mulch, preserving soil moisture. 

The timing of planting and turning under of cover crops is varied, depending on climate, soil requirements, and time of year.  Here in the north (Western Montana) our growing season is short so we have to be precise in our timing of planting, cutting and turning under cover crops.  After vegetables are harvested in the fall a cover crop can be planted immediately.  First, remove vegetable debris; second, till or rake and prepare a six-inch deep seedbed; third, irrigate to moisten soil; and finally, plant your cover crop.  Fall planted cover crops might include: hairy vetch, field peas, crimson clover, summer alfalfa, Mammoth red clover, annual rye grass, winter cereal rye, winter barley, winter wheat, winter oats ,or winter triticale.  Peas or hairy vetch planted together with one or another of the fall/winter cereal grains will add nitrogen and organic matter to the soil.  Oats and peas planted together or hairy vetch and winter rye together are quite effective combinations for fall cover crops.  The grain will protect the legumes somewhat from winter damage, though peas will probably winter kill.  Hairy vetch will vigorously regrow in the spring and can be mown and turned under.  Any cover crop of the grass family, such as cereal grain or annual ryegrass needs to be turned under at least three weeks before a vegetable crop is planted.  Some cereal grasses are allelopathic, which means they release growth inhibiting chemicals that prevent seed germination of other species.  It takes three or more weeks for the chemicals to dissipate.  Since our spring is often late, and short, and sometimes wet, the timing of turning under your cover crop is very important.  In a home garden, if you plan to plant some cool-weather crops early, such as onion sets, cole crops, or spinach, you can pull up or chop out a (non-grass family) cover crop in early spring just before you plant.  It is easy to hoe out hairy vetch by cutting it off below the crown.  You can then prepare the soil and plant immediately. 

Several cover crops can be planted in spring if you have about four to six weeks’ time before you plan to plant a crop.   An example might be if you plan to put in a warm-season crop such as peppers or tomatoes.  A cool-weather cover crop could be put in as soon as the soil could be worked (sometimes as early as April 10 or as late as May 5).  Some useful, early spring cover crops include: crimson clover, medium red clover, Mammoth red clover, white clover, or field peas.  If you have four to six weeks growing time plus three weeks’ time after taking down a cereal grass before you plant you could put in spring oats and field peas, or annual ryegrass.   The plot would be ready to plant your vegetable crop by mid to late June in our Montana climate.  This would limit your choices to fall-maturing cool-weather crops such as cauliflower, Brussels sprouts, lettuce, carrots, etc.

If you plan to have a cover crop during the warm season, buckwheat , mustard, turnips or phacelia all work well in our climate.  Remember to cut mustard or buckwheat when in flower so it will not reseed.   Phacelia will reseed also, but has a long blooming season and is a great pollinator attractant.  Turnips are biennial, so will not reseed the first year. 

In a home garden cover crops need to be considered in crop rotation.  It is best not to plant a cover crop of the Brassica family (Cole crops, such as turnips, mustard, radish, cabbage, etc.) where cole crops are to be planted the following season.  The rule of thumb is to rotate crops so that members of the same plant family are not grown in the same spot for three years or more.  In our certified organic market garden we use a nine year crop rotation plan.  A more practical home garden rotation plan might be only four-years. 

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ORGANIC VEGETABLE GARDENING

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ORGANIC VEGETABLE GARDENING

By James Sagmiller

The benefits of gardening organically are many.  First, food grown without dangerous pesticides and herbicides is safe for us and our children to eat.  Second, using organic methods protects our natural environment: soils are healthy, waters are protected from dangerous runoff, insects, birds, and water creatures are all unharmed by dangerous chemicals.  With organic methods, your soil becomes alive with organisms such as mycorrhizal fungi, which, through a symbiotic relationship with plant roots, increase a plant’s ability to uptake moisture and nutrients.  These fungi, along with beneficial soil bacteria, create an ideal, sustainable environment for crops—exactly the opposite of degraded soils exhausted through repeated use of chemical fertilizers. 

At first, planning to “go organic” might seem difficult, but I assure you the rewards are worth the time taken to learn easy ways of gardening organically.  Siting, fencing, and soil building are first steps.  Find a location for your garden that receives full sun, preferably one with wind protection.  If a site is windy, you can put lattice or privacy webbing on your fence to slow down the blast.  Shelter belt plantings of native trees and shrubs are excellent too.  Because deer are so prevalent nowadays, an 8-foot high fence is the best way to shield your garden.  Other methods are less effective.  I made my fence out of game fencing and 10-foot metal posts.  A 6-foot fence that hides what is on the other side will work also; if deer cannot see what is on the other side, they will not leap over.  Deer will eat anything if they are hungry enough! 

A soil test is very helpful before you begin your garden spot.  You can immediately see what nutrients you have in your soil and which ones you need to add more of.  It is also good to know the analysis of purchased soil amendments (marked with the letters N-P-K on fertilizer labels).   For high nitrogen contents (N on the label) choose blood meal, cottonseed meal, alfalfa meal, and composted manure.  Amendments with high phosphorous (P on the label) include fish bone meal and rock phosphate.  Potash (K on the label) is abundant in kelp meal, alfalfa meal and wood ashes.  Keep in mind wood ashes and bone meal become alkaline (higher pH) as they decompose, and cottonseed meal becomes more acidic (lower pH).  It is helpful to have a test kit and know your soil’s pH and NPK content.  Nitrogen promotes good green growth, phosphorous promotes flowering and fruiting, and potash encourages root growth and ripening of fruits and seeds.

To kill out grass and weeds for a new garden spot, use something safe that will shade the ground.  Some options are: landscape fabric with weights on it, newspaper covered with moist, heavy organic straw, or black plastic weighted down.  It takes a few weeks to kill out most plant material, but some perennial weeds will remain and seeds will sprout again.  If you are planning well ahead, you can immediately plant a soil-building cover crop to shade the soil until you plant vegetables.  If you need to start right away, till the soil, add organic amendments, plant your seeds and transplants, then mulch. 

When you plant seeds, choose organically certified seed if possible, especially for food plants.  Heirloom seed varieties, which are all open-pollinated, are excellent for organic gardening, because being generations-old, they are well-adapted to climates where they have been grown for a long time.  Heirlooms often ripen in succession rather than all at once, frequently are more nutritious, have exceptional taste, and seed can be saved from them to plant next year.  Another plus is that many heirloom varieties were developed to last well in storage—a valuable trait for local sustainability and for gardeners who want to be self-sufficient.

Mulching your garden is important to conserve moisture and provide for living soil organisms.  Landscape fabric, organic straw, compost, or composted grass clippings work well.  (Fresh grass clippings or other fresh greens will draw nitrogen out of the soil rather than add nitrogen.) 

Be sure to include a home for pollinators in or around your garden.  Native wildflowers are best; they will attract and foster native species of bees and other insects.  Another effective tactic is to release ladybugs, lacewings, praying mantises and other pest-eating bugs in your garden at proper times.  It is helpful to provide bird, bat houses and Mason bee houses.

Most gardeners new to organic gardening have anxiety about controlling pests and diseases.  Healthy, thriving plants, combined with preventative methods are the most effective ways to begin.  A diversity of crops will help confuse damaging insects (the scent of marigolds, for example confuses some pests).  Crop-rotation will prevent a host of pest and disease problems.  Plan your vegetable layout so that the same kind of plant is not grown in the same spot for at least 4 years.  Collars made from toilet paper rolls or plastic cups will deter cut worms.  Netting will prevent birds from eating strawberries.  Light insect fabric on row covers will protect all cole crops from cabbage loopers; and straw mulch around tomatoes will make a home for beetles, which will eat aphids off the tomatoes at night.  Garlic spray over your vegetables will confuse most damaging pests and prevent infestations if timed at monthly intervals.  Safe pesticides and fungicides, such as BT, horticultural oil, neem oil, insecticidal soap, pyrethrum, and diatomaceous earth are each effective for certain listed pests.  Always follow directions and precautions to the letter with any pesticides or herbicides. 

Take advantage of the latest technologies to assist your organic garden.  A few of these include: season-extending high or low tunnels, solar-powered heating and cooling, and frost-protection fabrics.  Using tunnels and row covers can improve yields significantly because you get a month to 6 weeks longer season of growing and harvesting!  Automatic solar vents for cold frames, greenhouses and high tunnels will save you labor and worry—especially in our volatile climate, with its ups and downs in temperature, alternating clouds and sunshine, and sudden winds that occur in a typical Montana spring.  Solar powered fans will kick on automatically when the temperature gets too high in a tunnel or greenhouse, and will not contribute to the overabundance of carbon dioxide in our atmosphere.  I wish you the best of luck and success in your organic gardening!