How To Make And Use Compost Tea In Your Garden
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If you already make compost, compost tea gives you another way to put that hard work to use.
Compost tea is simply finished compost steeped in water to create a liquid that you can apply to your garden. The process extracts some nutrients, organic compounds, and microorganisms from the compost and distributes them throughout garden beds, containers, and landscapes.
Gardeners have used compost tea for decades to support soil health, help transplants settle in, and provide plants with a gentle boost during the growing season. It won't replace good soil, mulch, or finished compost, but it can become another useful tool in your gardening routine.
Start With Good Compost
The quality of your compost tea depends almost entirely on the quality of the compost you use to make it.
Choose compost that smells earthy and pleasant and has finished breaking down into a dark, crumbly material. Avoid compost that smells sour, contains diseased plant material, or includes pet waste.
If your compost pile produces healthy compost, it will likely produce useful compost tea as well.
Making Compost Tea Doesn't Need to Be Complicated
If you spend much time reading about compost tea, you will quickly discover recipes that include aquarium pumps, molasses, fish emulsion, kelp extracts, and a surprising amount of equipment. While some gardeners enjoy experimenting with these methods, you do not need any of them to get started.
For a simple compost tea, place a few handfuls of finished compost into a bucket of water and allow it to steep for 24 to 48 hours. Stir the mixture occasionally and allow the water to take on the color of weak tea.
Many gardeners prefer to place the compost inside an old pillowcase, cheesecloth, or mesh laundry bag before brewing. The bag acts like a giant tea bag and makes cleanup dramatically easier when the process is complete.
Once brewing is finished, remove the compost and use the liquid soon after making it.
What Water Should You Use?
Rainwater and well water work particularly well because they contain little or no chlorine. Tap water works perfectly well for most situations, but some gardeners prefer to let chlorinated water sit overnight before brewing to allow some of the chlorine to dissipate.
How Should Compost Tea Smell?
Healthy compost tea should smell earthy, sweet, or similar to fresh soil after rain. If your batch smells rotten, sour, or sewage-like, discard it and start over. A foul smell usually indicates that undesirable anaerobic conditions developed during brewing.
When in doubt, trust your nose.
How Do You Use Compost Tea?
Most gardeners use compost tea as a soil drench rather than a foliar spray. Simply pour the tea around the base of plants and allow it to soak into the root zone where roots, soil organisms, and organic matter interact.
Vegetables, flowers, shrubs, trees, raised beds, and containers can all benefit from occasional applications during the growing season.
Many gardeners apply compost tea after transplanting seedlings, during periods of rapid growth, or after plants experience stress from heat or drought.
Morning and evening applications often work best because cooler temperatures reduce evaporation and place less stress on plants.
Compost Tea for Container Plants
Container plants can benefit particularly well from compost tea because they contain a limited amount of soil and regular watering flushes nutrients through pots more quickly than it does in the ground.
An occasional application as part of your normal root-zone watering routine can provide a gentle nutrient boost without the risk of overfertilizing. Compost tea can also help reintroduce some of the biological activity that naturally develops in larger garden soils.
Can You Spray Compost Tea On Leaves?
Some gardeners spray compost tea directly onto leaves as a foliar treatment, while others prefer to apply it only to the soil. Research on foliar applications remains mixed, and many home gardeners find that soil applications provide the simplest and most reliable results. If you choose to experiment with foliar applications, avoid spraying edible portions of crops that you plan to harvest soon.
For most gardeners, root-zone applications remain the simplest and most conservative approach.
What Should You Do With the Leftover Compost?
Do not throw it away. The compost still contains plenty of organic matter after brewing. Spread it around plants as a top dressing, mix it into containers or raised beds, or simply return it to your compost pile.
Compost tea borrows some of the benefits from compost, but it does not use them up.
Use Compost Tea While It's Fresh
Unlike many commercial fertilizers, compost tea does not store well. For best results, use it the same day you make it or within a day or two at most. Fresh tea generally contains the greatest biological activity and produces the most consistent results.
If it develops an unpleasant smell during storage, discard it and make a fresh batch next time.
Keep Expectations Realistic
Compost tea contains relatively small amounts of nutrients, so you should not think of it as a fertilizer replacement or a solution for poor soil. Instead, many gardeners use it as one small part of a larger soil-building strategy that includes compost, mulch, proper watering, and increasing organic matter over time.
Perhaps the biggest benefit of compost tea is that it encourages you to think about feeding your soil rather than simply feeding your plants. Used alongside other good gardening practices, compost tea can become another simple way to support healthy soil and healthy plants.
Composting Resources
Healthy Soil, Healthy Habitat