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How to make compost tea

Photo credit: Shutterstock

You want your cannabis plants to be happy and healthy (and you’d like to believe they feel the same way about you). You water them, give them nutrients (not too much), and a lot of fertilizer. But have you ever thought of asking them “do you want some tea?” (British accent optional). Specifically, we are talking about compost tea.

Many growers are starting to use compost tea on their cannabis plants, and everyone has their own favorite recipe. Here at WikiLeaf, we went to see one of the best for his point of view.

Benjamin runs is the chief producer of Puffin Farm. Their bud from living soil the use of compost tea has won awards from High Times Cannabis Cup, the Seattle Sun Cup and the Terp Festival. Benjamin has generously agreed to share how Puffin Farm makes their compost tea, some tips for farm and home growers, and the best ways to water your compost tea.

But first, let’s take a look at what exactly we’re talking about.

What is Compost Tea?

Compost tea is the liquid version of decomposed organic matter rich in microorganisms that you add to your plant’s soil to make them prosper.

a person scrapes food scraps, lettuce and other vegetables into a compost bin filled with soil and other scraps

Compost tea is simply “tea” made by steeping compost in water. Photo credit: Shutterstock

It’s made by “soaking” a mesh bag of compost into a container of hot water, which releases all those beneficial microorganisms and nutrients into the liquid.

Why use compost tea?

According to Benjamin, who has also been involved in compost research studies at Oregon State University, compost tea filters down to the root system and adds to the microbial life in the soil.

“The microbes will somehow be attracted to the root zone and feed [sugars] that the roots are freed, then in turn they go break down nutrients in the soil, making them more available to feed the roots, and also protecting them from… powdery mildew, damping off and other soil-borne diseases.

Compost tea also aids in disease suppression when added to foliar feeding (spraying nutrients directly on the leaves).

How to make compost tea

Compost tea is relatively inexpensive and easy to prepare. Recipes vary from specific ratios of ingredients to dumping store bought compost in a bucket of water, stirring it and saying you’re done. As Puffin Farm’s award-winning flower is known for its potency terpene content, we share this recipe below with the reasons for each ingredient. A good rule of thumb is to go for a compost to water ratio of 1:20 to 1:40. Here we go with 1:40.

Puffin Farm Compost Tea Recipe (with ratios for home growers):

  • 200 gallons of lukewarm water (40 parts) — “[Temperature-wise] around 70-80 degrees Fahrenheit is ideal…you don’t want it to be too cold because germs won’t grow…and too much above 80-85 degrees it will get all funky and grow things you don’t want in there…”
  • 5 gallon worm compost (1 part) — Store-bought is fine, but vermicompost contains more micronutrients.
  • 5 gallons (1 part) alfalfa — “It contains natural trichotonol, which is a growth stimulant. It helps a lot, especially with younger plants, to establish roots and keep them going.
  • ½ gallon rock dust (1/10th part) — “It’s not necessary, but it adds micronutrients and and… there’s a bit of everything in the rock dust.”
  • 4 cups (1/20th part) humic acid — “It’s naturally present in the soil…but we add a concentrated humic acid, which is quite high in potassium…”
  • 4 cups (1/20th parts) kelp — The kelp adds “various natural growth promoters and other good stuff…lots of micronutrients and potassium.”

Note: Many recipes call for the use of molasses, but Benjamin advises against this use. “From research I’ve seen, it can cause the growth of some unwanted bacteria like salmonella and E coli…adds to the growth of plant pathogens and decreases the amount of beneficial bacteria.”

Step 1: Obtain a vessel to serve as a brewer

While Puffin Farms uses a 250 gallon brewer to make their compost tea, a home grower can use something as small as a five gallon bucket.

Step 2: Add your water and circulate and aerate it

Microbes love oxygen, and circulating/airing means they are happy, nourished, and reproducing. There are many aerator/circulator options, starting at this 10 gallon compost tea infuser at this $30 clip on aerator. YouTube also has a lot of DIY Compost Tea Brewing Guides.

Step 3: Mix your compost

a person's hand digs a shovel into a plastic bin of compost soil

There are many different recipes for compost tea, but we recommend following Benjamin’s recipe from Puffin Farm as shown above. Photo credit: Shutterstock

Mix following the recipe above (more or less. It’s compost, not French cooking), then add it to a mesh bag and tie it up. Benjamin recommends a 400 micron bag which is the best balance to keep most sediment inside while allowing microbes to seep into the compost tea.

Step 4: Immerse your bag in circulating water

Make sure to keep the temperature around 70-80 degrees, then let it “steep” for about 48-72 hours. If you don’t have a circulator or automatic aerator, you should at least stir it liberally with a stick every morning and night.

Step 5: It’s tea time!

How to water your plants with compost tea

After your tea steeps, there will be a layer of sediment at the bottom of your container. This is not a problem if you pour your compost tea directly on the plants. However, sediment can clog drip irrigation pipes or sprayers. For this, Benjamin recommends that you connect your supply hose to the middle of the container.

When you water with compost tea,

“It’s especially beneficial in the beginning when your cannabis plants are getting established… But most of the season we’ll be hitting them like once a week with compost tea. Generally the more the better. it is.

Puffin Farm also foliar feeds its plants in the early stages to help prevent disease, but tapers off as the plants mature and stops once they are close to flowering.

It’s tea time (compost)

If you’re looking for a relatively cheap and easy way to have healthier, more productive plants, offer them compost tea. Beneficial microorganisms will help protect your plants against soil diseases and deliver more bioavailable nutrients to the roots, which will stimulate trichome production. So prepare a cup! It’s only polite when you invite a plant into your home.

Thanks to Benjamin Short for sharing his knowledge with WikiLeaf!

Frequently Asked Questions

How long does it take to make compost tea?

It takes a minimum of 24 hours, but it is recommended to steep for 48-72 hours (2-3 days).

How to make compost tea from kitchen scraps?

You will first need to compost kitchen scraps by putting them in a bucket with soil and worms to break down organic matter and establish a community of healthy microorganisms.

Can compost tea burn plants?

No. Compost tea does not contain enough nutrients to cause nutrient burn.

How to make compost tea for houseplants?

You would do this the same way as for outdoor plants.

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