Nourish your garden naturally without petrochemicals.
ROL STAFF
For organic gardeners, creating a
living soil rich in humus and nutrients is the key to growing great
fruits and vegetables, abundantflowers, and long-lived ornamental trees and
shrubs. The overall fertility and viability of the soil, rather than the
application of fertilizers as quick fixes, is at the very heart
of organic gardening.
But like all gardeners, organic gardeners have to
start somewhere. Your soil may be deficient in certain nutrients. It may
not have excellent soil structure. Its pH may be too high, or too low.
Unless you’ve lucked into the perfect soil, you’re going to have to work to
make it ideal for gardening.
Chemical Vs. Organic
Many organic materials serve as both fertilizers and soil conditioners—they
feed both soils and plants. This is one of the most important differences
between a chemical approach and an organic approach toward soil care and
fertilizing. Soluble chemical fertilizers contain mineral salts that plant
roots can absorb quickly. However, these salts do not provide a food source for
soil microorganisms and earthworms, and will even repel earthworms because they
acidify the soil. Over time, soils treated only with synthetic chemical
fertilizers lose organic matter and the all-important living organisms that
help to build a quality soil. As soil structure declines and water-holding
capacity diminishes, more and more of the chemical fertilizer applied will
leach through the soil. In turn, it will take ever-increasing amounts of
chemicals to stimulate plant growth. When you use organic fertilizers, you
avoid throwing your soil into this kind of crisis condition.
The manufacturing process of most chemical fertilizers depends on
nonrenewable resources, such as coal and natural gas. Others are made by
treating rock minerals with acids to make them more soluble. Fortunately, there
are more and more truly organic fertilizers coming on the market. These
products are made from natural plant and animal materials or from mined rock
minerals. However, the national standards that define and distinguish organic
fertilizers from chemical fertilizers are complicated, so it’s hard to be sure
that a commercial fertilizer product labeled “organic” truly contains only
safe, natural ingredients. Look for products labeled “natural organic,” “slow
release,” and “low analysis.” Be wary of products labeled organic that have an NPK
(nitrogen-phosphorus-potassium) ratio that adds up to more than 15. Ask a
reputable garden center owner to recommend fertilizer brands that meet organic
standards.
Using Organic Fertilizers
If you’re a gardener who’s making the switch from chemical to organic
fertilizers, you may be afraid that using organic materials will be more
complicated and less convenient than using premixed chemical fertilizers. Not
so! Organic fertilizer blends can be just as convenient and effective as
blended synthetic fertilizers. You don’t need to custom feed your plants
organically unless it’s an activity you enjoy. So while some experts will
spread a little blood meal around their tomatoes at planting, and then some
bonemeal just when the blossoms are about to pop, most gardeners will be
satisfied to make one or two applications of general-purpose organic fertilizer
throughout the garden.
Convenient products like dehydrated organic cow-manure pellets and liquid
seaweed make it easy to fertilize houseplants and containers too. (Don’t use
fish emulsion indoors, though, because of its strong odor. Save it for your
outdoor containers and garden plants.)
If you want to try a plant-specific approach to fertilizing, you can use a
variety of specialty organic fertilizers that are available from mail-order 231
supply companies or at most well-stocked garden centers and home centers. You
can find everything from organic tomato and rose fertilizer mixes to organic
fertilizer mixes especially created for transplants, lawns, heavy bloom
production, even containers.
You can also make custom mixes to address your plants’ specific needs. For
example, you can use bat and bird guano, composted chicken manure, blood meal,
chicken-feather meal, or fish meal as nitrogen sources. Bonemeal is a good
source of phosphorus, and kelp or greensand are organic sources of
potassium.
Dry Organic Fertilizers
Dry organic fertilizers can consist of a single material, such as rock
phosphate or kelp (a type of nutrient-rich seaweed), or they can be a blend of
many ingredients. Almost all organic fertilizers provide a broad array of
nutrients, but blends are specially formulated to provide balanced amounts of nitrogen, potassium, and phosphorus,
as well as micronutrients. There are several commercial blends, but you can
make your own general-purpose fertilizer by mixing individual amendments.
Applying Dry fertilizers
The most common way to apply dry fertilizer is to broadcast it and then hoe or
rake it into the top 4 to 6 inches of soil. You can add small amounts to
planting holes or rows as you plant seeds or transplants. Unlike dry synthetic
fertilizers, most organic fertilizers are nonburning and will not harm delicate
seedling roots.
During the growing season, boost plant growth by side-dressing dry
fertilizers in crop rows or around the drip line of trees or shrubs. It’s best
to work side-dressings into the top inch of the soil.
Liquid Organic Fertilizers
Use liquid fertilizers to give your plants a light nutrient boost or snack
every month or even every 2 weeks during the growing season. Simply mix the
foliar spray in the tank of a backpack sprayer, and spray all your plants at
the same time.
Plants can absorb liquid fertilizers through both their roots and through
leaf pores. Foliar feeding can supply nutrients when they are lacking or
unavailable in the soil, or when roots are stressed. It is especially effective
for giving fast-growing plants like vegetables an extra boost during the growing
season. Some foliar fertilizers, such as liquid seaweed (kelp), are rich in
micronutrients and growth hormones. These foliar sprays also appear to act as
catalysts, increasing nutrient uptake by plants. Compost tea and seaweed extract are
two common examples of organic foliar fertilizers.
Applying Liquid Fertilizers
With flowering and fruiting plants, foliar sprays are most useful during
critical periods (such as after transplanting or during fruit set) or periods
of drought or extreme temperatures. For leaf crops, some suppliers recommend
biweekly spraying.
When using liquid fertilizers, always follow label instructions for proper
dilution and application methods. You can use a surfactant, such as coconut oil
or a mild soap (¼ teaspoon per gallon of spray), to ensure better coverage of
the leaves. Otherwise, the spray may bead up on the foliage and you won’t get
maximum benefit. Measure the surfactant carefully; if you use too much, it may
damage plants. A slightly acid spray mixture is most effective, so check your
spray’s pH. Use small amounts of vinegar to lower pH and baking soda to raise
it. Aim for a pH of 6.0 to 6.5.
Any sprayer or mister will work, from hand-trigger units to knapsack
sprayers. Set your sprayer to emit as fine a spray as possible. Never use a
sprayer that has been used to apply herbicides.
The best times to spray are early morning and early evening, when the
liquids will be absorbed most quickly and won’t burn foliage. Choose a day when
no rain is forecast and temperatures aren’t extreme.
Spray until the liquid drips off the leaves. Concentrate the spray on leaf
undersides, where leaf pores are more likely to be open. You can also water in
liquid fertilizers around the root zone. A drip irrigation system can carry
liquid fertilizers to your plants. Kelp is a better product for this use, as
fish emulsion can clog the irrigation emitters.
Using Growth Enhancers
Growth enhancers are materials that help plants absorb nutrients more
effectively from the soil. The most common growth enhancer is kelp (a type of
seaweed), which has been used by farmers for centuries.
Kelp is sold as a dried meal or as an extract of the meal in liquid or
powdered form. It is totally safe and provides some 60 trace elements that
plants need in very small quantities. It also contains growth-promoting
hormones and enzymes. These compounds are still not fully understood, but are
involved in improving a plant’s growing conditions.
Applying Growth Enhancers
Follow the directions for spraying liquid fertilizers when applying growth
enhancers as a foliar spray.
You can also apply kelp extract or meal directly to the soil; soil
application will stimulate soil bacteria. This in turn increases fertility
through humus formation, aeration, and moisture retention.
Apply 1 to 2 pounds of kelp meal per 100 square feet of garden each spring.
Apply kelp extract once a month for the first 4 or 5 months of the growing
season.
If fresh seaweed is available, rinse it to remove the sea salt and spread
it over the soil surface in your garden as a mulch, or compost it. Seaweed decays readily because it contains little
cellulose.