A Cup of Tea for Your Garden: How & Why to Make Compost Tea
Compost tea is an easy, organic way to enhance your soil. It is rich in nutrients and microorganisms vital for plant and soil health. Compost tea is made by soaking composted materials in water, and then using the water in your garden.
There are a few different methods of making compost tea. Each one needs a relatively small amount of organic matter, and only takes a few days, or less, of brewing. Many gardeners find the benefits for their gardens are worth the little extra effort of brewing compost tea.
Benefits of Compost Tea
1. Provides a wide range of nutrients.
Compost tea contains all the water-soluble nutrients from your compost. This means that the richer your compost is, the more nutritious your tea will be.
The nutrients will naturally be more diluted than in straight compost, so there is no danger of harming your plants by over-fertilizing. You can give your plants compost tea regularly for gentle, ongoing nutrition support.
2. Boosts soil microorganisms.
Beneficial fungi, bacteria, nematodes and protozoa all naturally live in a healthy compost pile. Many of these microorganisms will multiply in a compost tea.
Microorganisms are what keep soils, and what grows in them, alive. A small particle of soil can contain thousands of different species of microbes. They break down organic matter, recycle nutrients, maintain soil structure, promote plant growth and control pests.
When you apply the high numbers of microbes typically found in compost tea, it will help the local plants and ecosystem literally from the ground up.
3. Suppresses diseases
Theres increasing evidence that plant diseases can be suppressed by treating plants with compost teas. Teas brewed from all different methods appear to have benefits.
This is most likely due to the enhanced microbial populations. They support plant health, and stronger plants are less disease-prone. Also, the beneficial microorganisms can out-compete and inhibit the harmful species both above and below ground.
What to Put in Your Compost Tea
The most important ingredient is, of course, high-quality compost. Compost made from diverse, healthy organic matter will give you the best compost tea. Well-aged compost is also preferable because the older it is, the more microorganisms it will have. It should have been decomposing for at least a few months.
The particles in your compost should be small and well broken down. This will make the nutrients and microorganisms more easily available to be released into the water.
If you have a worm box, worm castings also make excellent compost tea.
Its best to use well water or rain water if possible. If youre using tap water that contains chlorine, let it sit overnight for the chlorine to dissipate.
Manure isnt ideal for tea because its not as nutritionally well-balanced as a good compost. Research manure tea brewing before attempting it to make sure you dont spread possible manure-borne diseases.
Also, be cautious about adding extra ingredients to your compost tea. Plain compost naturally goes through a period of high temperatures as it decomposes. This will usually kill most pathogens.
But, some compost tea brewers recommend adding ingredients to increase the bacteria diversity in the tea. This is more common in aerated teas, which may add molasses, kelp, humic acid, fish hydrolase or other products.
These additives have not been heat-treated like compost and are shown to potentially increase dangerous bacteria like E. coli and Salmonella in compost teas. If youre using additives in your teas, avoid applying them to food crops.
Brewing Methods
One of the most important factors for a healthy compost tea is air. The beneficial microbes need oxygen in the water to reproduce. If you allow a tea to become stagnant, it promotes anaerobic, potentially harmful microbes to take hold.
You can maintain oxygen in your tea by either hand-stirring or installing an electric bubbler. Both methods are described below.
1. Anaerobic
This is the easiest method. You simply need to put some compost in a bucket, add water and let it steep for up to three weeks. Stirring it a couple times a day will help keep it oxygenated.
Any size of bucket or container will work, depending on how much compost tea you need. A good ratio is around one part compost to 3-10 parts water. If you make a more concentrated batch, you can dilute it more as you apply it.
Leaving your tea to steep longer will give the beneficial microorganisms more time to multiply. But dont leave your tea for much longer than three weeks, because it can start to stagnate and kill the beneficial microbes.
CaliKim has a great video that goes over the basics of anaerobic brewing.
2. Aerobic
Anaerobic teas have been brewed for centuries, but aerobic teas are a modern invention. They involve inserting an aeration device into your brewing compost tea, such as an aquarium pump. This will provide much more oxygen than simply stirring an anaerobic tea.
Instead of mixing compost directly into the water, it is suspended in a porous bag. This makes it easier to run a bubbler through the water. The nutrients and microbes will slowly leach out of the compost and into the water. It is only brewed for up to 24 hours.
A ratio of one part compost to 10-50 parts water is recommended, which is less than an anaerobic tea. This means the nutrients will be more dilute as there is less organic matter in the solution.
Its said this increased oxygen will produce more and better microbe populations. Currently, there is limited research to prove whether or not this is true. In fact, anaerobic compost teas are shown to have somewhat better disease controlling effects.
The only way to find out for sure is by experimenting with it in your own yard. If youd like to make your own aerated compost, Fine Gardening has an excellent description of how to set up a home bubbler system.
Many pre-made systems are available commercially if you dont want to make your own. Ask your local garden center if they can recommend one, or find one online.
You can also buy fresh compost tea at many garden centers. These are a good option if you dont have the time or interest in brewing your own.
Pre-packaged compost teas are available as well, although their quality is questionable. Alive and active microorganisms are a vital part of compost tea. These would be difficult to package for any length of time.
Using Your Compost Tea
Compost tea can be applied to any plants, either in the ground or in containers. Use it freely on your vegetables, flowering plants, trees, shrubs or lawn.
Most compost tea wont need dilution, unless you only have a small amount and want to make it go farther.
You can use compost tea as a drench by simply watering your plants with it.
Compost tea can also be applied as a foliar spray. Strain your tea through cheese cloth or a fine sieve first to remove any particles that could clog your sprayer. Adding a couple drops of mild dishwashing liquid will help the tea adhere to leaves better.
Foliar feeding with compost tea is shown to boost a plants immediate uptake of nutrients. Although, it doesnt appear to have any benefit on long-term soil fertility.
Make sure you use your tea as soon as its finished brewing to prevent any pathogen growth. If your compost tea smells bad, this likely means it hasnt gotten enough oxygen. Pour any rancid tea into an unused area of your compost and start a new batch of fresh tea.
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Disclaimer: The views expressed above are solely those of the author and may not reflect those of Care2, Inc., its employees or advertisers.
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