Compost teas are for plants what superfood smoothies are for humans – an instant boost of vitamins, minerals and nutrients. Compost teas promote vigorous root growth and expansion, they increase the biological diversity in the soil; they help break down toxins, and the best part is that compost teas reduce the need for chemical inputs in your garden.
Compost teas are an efficient way to extract the valuable nutrients and microbes out of compost by using water, oxygen, and agitation. By steeping a small amount of compost in water, you can extend the life of your compost. Making teas are an excellent way to feed your plants organically on a budget.
Compost teas are a versatile amendment; you can apply by watering it into the soil or by foliar-spraying directly onto the leaves. Either way, you’re providing your plants with highly available nutrients along with a healthy dose of beneficial bacterias and fungi. A good compost tea will breed billions of microorganisms such as bacteria, fungi, protozoa, and nematodes. When poured into the soil the compost tea will not only provide immediate nutrients to your plants but also help replenish the soil food web.
Making an aerated compost tea requires a few basic ingredients: an inoculant of bacteria or fungi, a food source for the microorganisms, water, oxygen, and agitation.
The quality of your starting material will determine the quality of your compost tea. A tea will only concentrate the bacteria and/or fungi that are present in the starting material. You ideally want a balanced ratio of bacteria and fungi, but some plants prefer specific brews. Annual plants ordinarily prefer bacteria-dominant while trees prefer fungi-dominant teas. Fresh compost (1-3 months) is generally more bacteria-dominant while older compost (3-6 months) is more fungi-dominant. A quick tip to add fungi into your compost tea is to collect a cup or two of soil from a nearby forest to add into your brew.
In order for compost teas to flourish, the microorganisms need a steady food source. With something to eat, the fungi and bacteria will multiply rapidly. Bacteria loves simple sugars. Organic molasses or organic coconut sugar are great to add to your brew as an essential food source. Fungi likes more complex sugars and proteins, kelp, oatmeal, fruit pulp, and aloe extract are commonly used (make sure everything is organic and free from preservatives.) Many of these are inexpensive household items and in some cases can even be grown at home.
The more diverse your inputs are, the more biologically diverse your tea will be.
Worm castings (vermicompost) are amazing for cannabis compost teas because they serve as a great bacteria inoculant and act as a humic acid-rich food source at the same time. A tea made out of worm castings is called a vermi-tea. Vermicompost can usually be found from great local sources but be sure to do your research on what the worms were fed, because that will determine the quality of the castings. It’s also relatively simple to build your own worm farm, all you need is a dedicated place, worms and some food to feed them (they love cannabis leaves).
Last thing we’ll touch upon is aeration, which is definitely not something to overlook. Compost teas need high aeration because it prevents the overgrowth of any harmful pathogens such as e.coli. Aeration can be achieved with airstones and air pumps if you’re working with a homemade system or you can find specialty compost tea brewers with built-in aeration systems.
Here are two recipes to get you started – the first utilizes a compost brewer which means it requires a few more supplies while the second recipe is a simple steeped tea.
Basic Aerated Compost Tea Recipe
Clean 5-Gallon Bucket
10 feet of ⅛ in. Plastic Tubing
Dechlorinated Water / Rainwater
1 Compost Tea Bag (must be at least 400 micrometers to allow microorganisms to pass through)
1 cup of inoculant (compost or worm castings)
¼ cup of microbe food source (listed in the chart above)
1 tablespoon of sugar (organic molasses, organic cane sugar or organic coconut sugar)
- Fill your 5 gallon bucket with dechlorinated water (to dechlorinate tap water, let it sit out, uncovered for 24 hours)
- Attach your airstones to the air pump using ⅛ in tubing – 5 feet of plastic tubing per airstone. Place the stones at the bottom of the bucket. *You want to be sure the agitation is strong enough to actually knock the microbes off the compost so you’re looking for the equivalent of a rolling boil.
- Fill your tea bag with the inoculant, microbe food source, sugar, and any other dry amendments.
- Place your sealed tea bag in the bubbling water and let infuse for 24-36 hours.
When the compost tea is done, you can remove the tea bag and use the tea as a foliar spray or feed it directly into the soil.You should definitely use the tea within 4 hours after it stops bubbling or else oxygen will quickly spoil your concoction.
Basic Herbal Tea Recipe
If you don’t have the means to make your own aerating compost bucket, you can still make a really basic tea. This method is best for plant-only inputs because it will lack aeration which could breed e.coli or other harmful pathogens if manure-based compost is used.
5 Gallon Bucket
Nutritious plant material – you can choose any plants from around your property, even weeds! Popular choices are cover crops that would already be planted around your beds such as, clover, buckwheat, comfrey, horsetail and stinging nettle.
- Fill your bucket about ¾ of the way full of plant material.
- Fill it up to the top with water.
- Let sit for 5-10 days, stirring once a day
- After your brew is done, be sure to filter with 400 micrometer screen and dilute to 1:10 ratio.
And it’s that simple! You now have a potent tea made from plants on your land that your cannabis crop will go crazy over.
Compost teas are a great organic method of bringing diverse biological life into your garden. Once you start, it’s hard to stop! There is an endless amount of recipes and inputs you can experiment with in the compost world. Once you have a couple successful brews, it’s fun to experiment with various local sources to find what your plants love best. If you stumble upon any groundbreaking discoveries, we’d love to hear them in the comments below.