How to Make Compost Tea: A Guide to an Amazing Plant Elixir

Gardeners know compost will enrich their garden soil and aid their flowers and vegetables to thrive. Compost tea is easy to make and has many benefits for the garden and indoor plants.

What Is Compost Tea?
As the name implies, compost tea is a liquid derived from 'steeping' or 'brewing' compost in water. It is nutrient-rich, especially in nitrogen and has beneficial micro-organisms in it.

Why Brew Compost Tea?
Compost tea can be used to drench the soil after seedlings have been transplanted into the garden. The tea aids the seedling transplant in developing a strong root system. For this reason, it can be used to nourish seedlings in flats. The tea can also be applied to houseplants. Plants which seem droopy or unhealthy benefit from the nutrient shot the tea gives when fed into the soil beside them. It is a good replacement for fertilizers or pesticides which may be toxic. Compost tea restores helpful micro-organisms into the garden that were killed off by use of chemical fertilizers and pesticides. It supplements whatever has already been done to enrich the soil.

Compost tea is also sprayed directly onto the leaves of vegetable, flowering, and berry plants, as well as shrubs and trees. When sprayed like this, the tea serves as short term protection against various diseases including potato blight, powdery and downy mildew, and fungal problems. It is not a cure for plants with already existent diseases. If there are toxins present, the speed at which they decompose is increased when compost tea is applied to the leaves. Dr. Elaine Ingham, a well-known microbial ecologist and professor at Oregon State University claimed in her article "Brewing Compost Tea" that vegetables from a garden where compost tea is applied have a better taste and greater nutritional quality.

Materials Needed to Make Compost Tea
Compost how-to books from the late 1990's had simplified instructions for making compost tea. Some claimed all the gardener needed was at least a quart of compost, a five-gallon pail, water, and some type of strainer. Other books said the gardener should use a 55 gallon barrel, a pillowcase or cheesecloth or burlap bag filled with compost and tied off at the top, water, and a pail in which to dip out the tea.

The gardener could purchase a compost tea system like the KIS (Keep It Simple) 10 gallon composter for between $500 to $650 or the 5 gallon Happy Farmer Kitchen Composter with tea spigot for around $60 to $75. These look like a large picnic thermos with a ventilated top and a spigot. They generally come with a large internal air pump, compost tea catalyst, and a screened bucket.

Dr. Ingham suggests the gardener can make his own tea brewer with the following materials:

-a five gallon plastic bucket in which to steep the tea
-one gallon of mature compost
-an aquarium pump
-one gang valve
-at least three feet of plastic hose
-one ounce of unsulfured molasses
-four gallons of unchlorinated water
-a second five gallon pail in which to collect the steeped tea
-an old nylon stocking, pantyhose leg, pillowcase, or flour sack towel to strain the tea

The compost used must have heated to a sufficient degree in the pile so as to kill off the pathogens and weed seeds in it. Fruit trees and berries will require a tea made from compost with fungal micro-organisms in it while vegetables and flowers will benefit from a tea made from compost with bacterial micro-organisms. Any good compost how-to book will instruct as to what ingredients will make either kind of compost.

The aquarium equipment (the pump, the gang valve, and the hose) is essential for keeping enough oxygen in the tea for the micro-organisms to live and multiply. A shortage of oxygen will kill the micro-organisms that are important for the tea to be beneficial. Hose instead of tubing should be used to provide the best aeration.

The unsulfured molasses will provide food for the thriving and reproducing bacterial micro-organisms.

If the water to be used is city water from the tap, it must be aerated for an hour to eliminate the chlorine. Chlorine kills the micro-organisms in the compost tea.

Setting Up the Compost Tea Maker
1. Cut the plastic hose to make three equal length pieces.
2. Attach the hose pieces to the gang valve.
3. Attach the gang valve to the lip of the bucket. Make sure the ends of the three hoses are in the bottom of the bucket. Attach the valve to the aeration pump.
4. Add the compost so the three hose ends are covered.
5. Add the unchlorinated water to the bucket.
6. Add the molasses.
7. Turn on the pump.
8. Let the pump run for two or three days.
9. Every once in a while, manually stir the mixture.
10. After three days, strain the tea into the other five gallon bucket.

All of the compost tea should be used immediately. When removed from the source of oxygen, the micro-organisms will begin to die and the tea will become less effective.

A turkey baster with a rubber bulb top can be utilized to inoculate the soil around houseplants and garden plants.

The soaked compost can be dug into the soil around garden plants or put back into the compost pile. Using the compost once for making tea will not remove all of the micro-organisms or nutrients from it.

Dr. Ingham suggests spraying garden plants early in the morning. Seedlings should not be sprayed until they have one or more sets of true leaves. If the garden has a good population of beneficial garden insects like ladybugs, they will carry the micro-organisms from the compost tea from plant to plant.

The spray can be used on the garden plants on either a monthly or bimonthly basis. Roses, tomatoes, and lilacs may be sprayed every two weeks with compost tea from the beginning of the growing season to the middle but not beyond.

Final Warning Words
Some older books on composting will say to skip the aeration pump and just stick the compost and water together, leave it for one or two weeks, stirring it often, and then use the resultant tea. The current recommendations are for the use of the air pump to allow the beneficial micro-organisms to grow and reproduce.

A non-earthy foul smell in compost as well as in compost tea means something has gone wrong in the mixture. The tea should smell like soil with a sweet odor. If it does not, put all of it into the compost pile and start over again. The foul-smelling tea will damage your plants if sprayed on the leaves or used for watering.

Research has shown if the starter compost has any human pathogens in it as would come from blood, urine, or feces, the addition of a commercial catalyst will allow the pathogens like E. coli and salmonella in the compost to multiply. The vegetables treated with this kind of tea can cause illness.

If the gardener sprays or side dresses with compost tea too often, his plants will develop symptoms showing too much nitrogen has been added. This will include: yellowing or light green, not dark and lush, foliage; retarded growth; and yellowed weak stems.

Compost tea has many benefits if prepared with the proper equipment and in the correct manner. Garden and houseplants alike love it.

Resources:

Elaine Ingham. " Brewing Compost Tea." [Online] http://www.taunton.com/finegardening/how-to/articles/brewing-compost-tea.aspx
Sharon Durham. "Recommendations For a Safer Compost Tea." September 21, 2006. [Online]
http://www.ars.usda.gov/is/pr/2006/060921.htm
Hanson, Beth, ed. Easy Compost: The Secret to Great Soil and Spectacular Plants. Brooklyn, New York: Brooklyn Botanic Garden, Inc., 1997.
Campbell, Stu. Let It Rot! The Gardener's Guide to Composting. Pownal, VT: Storey Books, 1998.
Cullen, Mark, and Lorraine Johnson. The Urban/Suburban Composter: The Complete Guide to Backyard, Balcony, and Apartment Composting. New York: St. Martin's Press, 1992.