Compost is a staple for gardeners, providing essential nutrients and improving soil health without harming the environment. Compost tea takes it a step further, offering an easy, chemical-free boost for plants. Despite its benefits, many gardeners have yet to try making their own compost tea, which is surprisingly simple and offers excellent results.
What is Compost Tea?
Compost tea is a liquid made by steeping compost in water, similar to brewing a cup of tea. Instead of traditional tea leaves, you use compost, which can include vermicompost (worm castings). There are two main types of compost tea: aerated (ACT) and non-aerated (NCT). ACT is the most commonly used and involves adding oxygen to the water to maintain beneficial microorganisms like bacteria, fungi, and protozoa that thrive in a well-aerated environment.
NCT, on the other hand, is simpler to make but doesn’t support as many microorganisms. Both types provide valuable nutrients and improve soil health, though ACT tends to be more potent for disease control and microbial diversity.
Why Use Compost Tea?
Compost tea is a natural, low-cost way to feed your plants. It offers several benefits:
- Nutrient-Rich: Compost tea contains key macronutrients (nitrogen, phosphorus, potassium) and essential micronutrients like copper, zinc, and iron, which plants need to thrive.
- Soil Health: The microorganisms in compost tea improve soil structure and encourage beneficial bacteria while suppressing harmful pathogens.
- Disease Resistance: Studies show that compost tea can protect plants from diseases like powdery mildew, downy mildew, and soilborne pathogens such as Rhizoctonia solani.
In contrast to chemical fertilizers, compost tea is free from harmful salts and ammonia, which can harm soil life and lead to fertilizer burn. Its organic nitrogen is also more easily absorbed by plants.
How to Prepare Compost Tea
To make compost tea, the quality of your compost and water are essential. Use mature, well-rotted compost (ideally between 90-110°F) to avoid pathogens and ensure the presence of beneficial microbes. For water, rainwater is ideal, but if using tap water, remove chlorine by aerating it or letting it sit for 24 hours.
Aerated Compost Tea (ACT)
- Setup: Fill a 5-gallon bucket halfway with water. Add compost until the bucket is nearly full, leaving about an inch of space at the top. Stir the mixture thoroughly to combine.
- Aeration: Stir the mixture 2-3 times daily to keep oxygen flowing. Alternatively, use an aquarium air pump and air stones to keep the tea aerated.
- Optional Additions: Add molasses (1 tablespoon per 5 gallons) to feed the microbes, encouraging growth.
- Brew Time: Tea made with aeration will be ready in 3-4 days, while stirring alone may take up to two weeks.
- Check for Odors: If the tea smells foul, discard it and start over. A good tea will have a pleasant, earthy aroma.
Non-Aerated Compost Tea (NCT)
- Setup: In a bucket, mix clean water with compost, leaving space at the top. Let it sit for up to two weeks, checking regularly for molds or unpleasant smells.
- Brew Time: Non-aerated tea takes longer to brew, but it’s simpler and doesn’t require constant attention.
Filtering and Application
After brewing, filter out the solids using a fine mesh (400 mesh is ideal). You can use a filter with a handle or a mesh cloth to strain the liquid. The tea can be applied as a foliar spray or soil drench.
- Foliar Spray: Apply the tea directly to plant leaves, covering about 75% of the surface. Dilute with water if needed (1 part tea to 4 parts water). Apply early in the morning or late afternoon to avoid the hottest part of the day.
- Soil Drench: Apply about 1 pint of tea per plant. Compost tea works for both potted and in-ground plants, including indoor and greenhouse plants.
The tea should be used within 6-8 hours after brewing as the oxygen levels decrease over time. If storing it, keep it cool and out of direct sunlight for up to 5 days.
Optional Additions
For enhanced results, you can experiment with additional ingredients:
- Molasses and Kelp: Add 2 parts unsulfured molasses, 1 part kelp, and 1 part fruit juice to nourish the microbes.
- Humic Acid and Protein: Add liquid humic acid (rich in carbon) or insect frass to further enrich the tea.
Conclusion
Compost tea is a powerful, eco-friendly alternative to chemical fertilizers. By brewing it yourself, you’ll give your plants a natural boost, improve your soil, and protect your garden from diseases—without any harmful chemicals. Whether you choose aerated or non-aerated tea, the process is simple, and the results are worth the effort. Happy gardening!