When to Apply Compost Tea

Put compost tea in that watering can to help fight plant disease and boost plant health.
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Compost tea, a liquid fertilizer created by brewing compost in water, makes nutrients more immediately available to plants than the process of adding solid compost to the garden bed (see References 2). According to the U.S. Environmental Protection Agency, compost tea effectively extracts nutrients and beneficial microorganisms from solid compost and makes them available to plants in liquid form. Gardeners may gently pour compost tea directly onto a plant's foliage, allowing the plant immediate nourishment and protection against disease from this liquid fertilizer.


Apply compost tea only after brewing it properly, notes "Rodale's Ultimate Encyclopedia of Organic Gardening." Use fully matured material, which the Rodale volume defines as a compost pile maintained at a temperature of 135 to 155 degrees Fahrenheit for at least a week or compost that has broken down slowly for at least a year. Bagged compost made from garden material may be suitable for brewing, provided it comes from a reputable company. Put finished compost in a burlap bag and steep it in water in a large container, such as a plastic garbage can. Soak about 10 lbs. of finished compost for every 10 gallons of water, and stir the mixture occasionally. Strain the liquid through cheesecloth or another burlap bag. The tea itself must brew for at least five days if soaked in a bucket the traditional way or two to three days if you speed the process with an aquarium pump (see References 3).

Shelf Life

Compost tea requires immediate application once the brewing and straining process is complete, according to the Pennsylvania Department of Environmental Protection. After the tea is strained and the compost source no longer exists to produce microbes, the microbes in the strained liquid begin to die. Plan your brewing schedule to complement your feeding schedule. After the compost tea steeps for three to seven days, strain and use it immediately. If you have more liquid than you do plants to fertilize, pour the excess tea into the garden soil or onto a compost heap (see References 3).

Problem Solving

Apply compost tea to plants whenever you spot signs of disease or undernourishment. Signs of fungal disease include wilting foliage, failure to flower or set fruit, and discolored leaves. Other diseases and pest problems also produce these general symptoms, but parasitic fungi may be apparent by the presence of dots or spirals (fungal spores) on the plants. Undernourished plants may have yellowing leaves, stunted growth and smaller than normal flowers or fruits. The microbes in compost tea may help these problems by combating fungi and boosting soil fertility while providing nutrients directly to plants (see References 2).


Fully mature compost doesn't host harmful bacteria, such as E. coli, which may be present in "raw" compost. To be certain that you don't inadvertently transfer these dangerous bacteria to your garden through compost tea, the Rodale volume recommends exercising extreme caution with edible crops. Estimate the harvest time of the fruits, herbs and vegetables you are growing and don't apply compost tea during the three-week period prior to harvest.

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