Once you have fully mature, nice-smelling compost, it's time to brew tea. You will need a 5-gallon plastic bucket and a few aquarium supplies: a pump large enough to run three bubblers (also called air stones), several feet of air tubing, a gang valve (which distributes the air coming from the pump to the tubes going to the bubblers), and three bubblers. You'll also need a stick for stirring the mixture, some unsulfured molasses (preferably organic), and an old pillowcase, tea towel, or nylon stocking for straining the tea. An extra bucket comes in handy for decanting the tea. Don't try to make compost tea without the aeration equipment. If the tea is not aerated constantly, the organisms in it will quickly use up the oxygen, and the tea will start to stink and become anaerobic. An anaerobic tea can harm your plants.

Also, keep in mind that tea made using this bucket method needs to brew for two or three days and then be used immediately. If you work Monday through Friday, start the tea on Wednesday or Thursday, so it will be ready in time to apply it on the weekend.

If you're on a well, you can use water straight from the spigot. But if you're using city water, run the bubblers in it for about an hour first, to blow off any chlorine. Otherwise, the chlorine will kill all those beneficial organisms you've gone to the trouble of raising.

Tea time

Once you have safe water, fill the empty bucket half full of compost. Don't pack it in; the bubblers need loose compost to aerate properly. Cut a length of tubing and attach one end to the pump and the other to the gang valve. Cut three more lengths of tubing long enough to reach comfortably from the rim to the bottom of the bucket. Connect each one to a port on the gang valve and push a bubbler into the other end.

Hang the gang valve on the lip of the bucket and bury the bubblers at the bottom, under the compost. Fill the bucket to within 3 inches of the rim with water, and start the pump.

When it's going, add 1 oz. of molasses, then stir vigorously with the stick. The molasses feeds the bacteria and gets the beneficial species growing really well. After stirring, you'll need to rearrange the bubblers so they're on the bottom and well spaced. Try to stir the tea at least a few times a day. A vigorous mixing with the stick shakes more organisms loose and into the tea. Every time you stir, be sure to reposition the bubblers.

After three days, turn off the pump and remove the equipment. If you leave the tea aerating longer than three days, you must add more molasses or the good organisms will start going to sleep because they don't have enough food to stay active. Let the brew sit until the compost is pretty much settled out, 10 to 20 minutes, then strain it into the other bucket or directly into your sprayer. You'll have about 2 1/2 gallons of tea. If you want, this is the time to add foliar micronutrients, like kelp or rock dust. Use the tea right away, within the hour if possible.

You can put the solids back on the compost pile or add them to the soil. There are plenty of good bacterial and fungal foods left in them.

Follow your nose

With any form of compost, solid or tea, bad smells mean bad business. Healthy, adequately oxygenated compost and compost tea should smell sweet and earthy. Never use a smelly compost tea on your plants. The true bugaboo is alcohol, a product of anaerobic decomposition that destroys cell walls. Roots tolerate only 1 part per million alcohol. That's a very small amount, and human noses aren't good at detecting it. Instead, we can detect all the other smelly compounds that go with anaerobic production of alcohol.

If your compost tea smells bad, add a second pump with more bubblers, and stir it more often. Aerate it until the smell goes away. Likewise, if your compost pile smells bad, turn it more frequently.

Using the tea

How often to spray your plants with tea depends on how healthy your garden is. In my garden, which has had no pesticide use since 1986, I spray my plants one time in spring, then let the beneficial insects spread the compost tea organisms around the plants in my garden, preventing any pest problems for the rest of the season.

Beneficial insect presence is a good indicator of your garden's health. If you don't have good levels of beneficial insects in your garden, then spray at least once a month, or as often as once every two weeks. Start when plants have developed their first set of true leaves.

To control damping-off, spray the soil with full-strength tea as soon as you plant. On trees and shrubs, spray two weeks before bud break, then every 10 to 14 days. You'll have to spray every 10 days if you have a neighbor who sprays pesticides, because pesticides kill the beneficial organisms as well as some of the pests.

Elaine R. Ingham is president and director of research at Soil Foodweb, Inc., and a research associate professor at Oregon State University in Corvallis.

Photos on this page courtesy of The Taunton Press.