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Use Compost Tea To Nourish Your Cannabis Plants

Compost tea is rich in nutrients and beneficial microorganisms such as nematodes, protozoa, certain bacteria, and fungi. This elixir can help to defend your plants against pathogens, and may also help to enhance growth and overall health.

Learn the ins and outs of using compost tea to nourish and protect cannabis plants.

  • 1. Bacterial vs fungal compost teas
  • 2. Start with good compost
  • 3. Understanding the different types of compost tea
  • 3.a. Aerated compost tea
  • 4. Sensibilità del test antidroga
  • 5. Compost tea in hydroponic and aeroponic systems
  • 6. The benefits of compost tea
  • 6.a. Compost tea recipe
  • 7. The benefits of sprouted seed tea
  • 7.a. Sprouted seed tea recipe
  • 1. Bacterial vs fungal compost teas
  • 2. Start with good compost
  • 3. Understanding the different types of compost tea
  • 3.a. Aerated compost tea
  • 4. Sensibilità del test antidroga
  • 5. Compost tea in hydroponic and aeroponic systems
  • 6. The benefits of compost tea
  • 6.a. Compost tea recipe
  • 7. The benefits of sprouted seed tea
  • 7.a. Sprouted seed tea recipe

Compost tea is a form of brewed compost that can provide your cannabis plants with plenty of high-quality nutrients, contributing to plant health, vigour, and even defence against pathogens. Despite its many beneficial effects, compost tea isn’t hard to make and requires minimal cost and effort. The main requirement for the tea is simply a bit of patience.

BACTERIAL VS FUNGAL COMPOST TEAS

When brewing compost tea, you’ll be extracting microorganisms from compost and feeding them to create a brew enriched with millions of beneficial bacterial or fungal colonies. These not only feed your plants, but can also help protect them from pathogens.

Compost teas can be either fungal or bacterial depending on what ingredients you use to brew them. Bacterial teas are made with sugars (like molasses), while fungal teas use fish hydrolysate and humic acid. While the brewing process is similar for both, fungal teas tend to take longer as fungal colonies grow at slower rates.

START WITH GOOD COMPOST

The key to good compost tea, you guessed it, is good compost. Compost is the result of the slow degeneration of natural waste materials such as fruit and vegetable peels, eggshells, paper, and garden trimmings.

If you’re composting at home, you’ll need a compost bin, which you can either buy online, from a garden centre, or build yourself. From there on out, you’ll want to feed your compost with a good combination of green and brown materials. For the best results, we recommend feeding your compost with 25–50% green materials and 50–75% brown materials. Check the infographic above for examples of both green and brown compost ingredients.

Over time, the microorganisms in your compost bin will break down these materials into compost, a soil conditioner rich in nutrients and microscopic organisms. If you don’t have your own compost to make tea with, you can either source some from your local garden centre or make a tea with store-bought ingredients. Some common ingredients for compost tea include:

FUNGAL COMPOST TEA

INGREDIENTS FOR COMPOST TEA (Bacterial and Fungal)
INGREDIENTS BACTERIAL COMPOST TEA FUNGAL COMPOST TEA BACTERIAL & FUNGAL COMPOST TEA
Fish hydrolysate X
Kelp X
Insect frass X
Alfalfa X
Glacial rock X
Azomite X
Bokashi X
Humic/fulvic acid X
Molasses X
Yucca X
Guano X

Remember: The ingredients you choose to use in your tea will determine whether it is fungal or bacterial.

UNDERSTANDING THE DIFFERENT TYPES OF COMPOST TEA

There are essentially six different types of compost tea: aerated tea, non-aerated tea, anaerobic tea, manure tea, compost leachate, and fermented plant tea. The most common tea used by both hobby and professional cannabis growers is aerated compost tea (or ACT).

AERATED COMPOST TEA

Aerated compost teas, as the name suggests, use oxygen during the brewing process to create the perfect environment for the growth of beneficial microorganisms. If you’re brewing at home, you can make your own ACT using a 20l bucket, an air pump/air stone, and the following base ingredients:

• High-quality compost
• Worm castings
• Humus

The base ingredients of any compost tea are compost, worm castings, and humus. These ingredients are rich in microorganisms, which you’ll grow as you feed your tea. Remember, using organic ingredients produces the best quality tea and the cleanest results.

• Feed

In order to grow the bacteria and fungi in your compost, you need to feed them the right nutrients. There are many different compost tea recipes available on the internet, and we’ve included one of our favourites at the end of this article.

• Oxygen

Aerated compost teas rely on oxygen to help support the growth of beneficial bacteria and fungi. For the home grower, simply letting your ingredients brew in a bucket with an air pump should be enough. Large-scale operations with bigger budgets, on the other hand, tend to use oxygen probes for complete control over the oxygen levels in their teas.

• Temperature and time

Aerated compost teas are best brewed at temperatures between 18–30°C. Lower temperatures make it harder for microorganisms to reproduce, while hotter temperatures may promote the growth of pathogens in your tea.

Time has a similar effect on compost tea. Microorganisms take time to grow, but over-brewing creates a breeding ground for bad bacteria and fungi. To play it safe, we recommend brewing your tea for exactly 24 hours.

TOOLS FOR MEASURING THE CONDUCTIVITY OF YOUR COMPOST TEA

Rather than blindly brewing and feeding your plants with compost tea, you’ll want to measure the conductivity of your brew to get a clearer picture of its content. Use the RQS pH and conductivity testers to ensure you’re doing right by your plants.

COMPOST TEA IN HYDROPONIC AND AEROPONIC SYSTEMS

While we tend to think of using compost teas with soil-grown cannabis, they can also be used in hydro or aero setups; you’ll just need to adjust your dosage. For soil-grown plants, we recommend using roughly 120ml per litre of water. In hydro, we recommend feeding 1 litre of tea per 30l of reservoir water.

Unlike chemical fertilisers, it’s a lot harder to overfeed your plants with compost tea.

THE BENEFITS OF COMPOST TEA

Compost tea contains millions of beneficial bacteria and fungi. By applying it to your plants’ roots or spraying it on their leaves, you’ll benefit their development in numerous ways.

Some of the main benefits of compost tea include:

ENHANCES PLANT GROWTH

Compost tea can assist the cannabis grower and their plants in numerous ways. One of its main benefits, and perhaps the most important to many growers out there, is that it helps to boost plant growth—a very important factor for those cultivators looking for large and resinous buds when harvest time swings around.

The sheer volume of nutrients within compost tea massively assists in the health of plants, ensuring proper and robust development. Such a potent dose of nutrients will help prevent deficiencies from setting in, which can ultimately reduce yields and obstruct proper growth and size.

INTRODUCES BENEFICIAL MICROORGANISMS

As well as introducing nutrients into the soil, compost tea will also bring beneficial microorganisms onto the scene, which include lifeforms such as mycorrhizal fungi and predatory nematodes.

Mycorrhizal fungi can help boost the root network of cannabis plants, allowing them to extract nutrients from further afield, boosting their uptake. These fungi can also help to defend roots against microbial parasites. Predatory nematodes also act as a natural defence, feeding upon microbes that have an appetite for cannabis roots.

Compost tea will also introduce predatory nematodes into the rhizosphere of your herbal garden. These tiny, worm-like creatures help to protect plants against a variety of other microorganisms, including others types of nematodes.

When compost tea is applied as a foliar spray, the nematodes within can even attack and defend against insect pests on leaves and stems, such as leaf miners.

Compost tea is a liquid dilution of compost that can be added to soil or used as a foliar spray. It's loaded with nutrients and beneficial microorganisms.

The best compost tea recipe

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Contents

  1. Benefits of compost tea
  2. How long does it take to make compost tea?
  3. What is the best compost tea recipe?
  4. What you need to make compost tea
  5. Steps to making compost tea
  6. Can you burn your plants with compost tea?
  7. Bottom line on compost tea

If you’re a cannabis grower interested in the zero-waste movement , compost tea could be a good place to start. This is not the kind of tea that you pour into a mug and sip. Compost tea is an organic mix of active nutrients and microorganisms steeped in aerated water. The brew packs a nutritional powerhouse for soil, roots, and leaves, introducing healthy fungal colonies (think of how probiotics benefit the digestive system) and beneficial bacteria to cannabis plants. The results are a boost in plant growth and protection from disease.

Benefits of compost tea

Though not all growers agree on whether compost tea is any more effective than ordinary compost, some cultivators have pinpointed these potential benefits:

  • Reducing the presence of weeds and pests, which consequently helps cannabis plants fend off diseases such as blight. Compost tea may shield marijuana from pathogens that could harm or even kill the plant.
  • Infusing the cannabis plant with a strong dose of nutrients, which can potentially increase plant size due to a strengthened immune system from a diversity of trace minerals.
  • Eliminating the need for chemical fertilizers that ultimately harm the soil and the environment when contaminated water leads to runoff and seeps into public water supplies. With compost tea, you are creating something 100% organic, which facilitates a thriving and self-sustaining ecosystem.
  • Maximizing water retention in the soil, meaning less wasted water.
  • Improving the overall health of the plant with a beneficial cocktail of fungi, bacteria, protozoa, and nematodes of multiple species.

Some cultivators have pinpointed potential benefits of compost tea. Photo by: Gina Coleman/Weedmaps

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How long does it take to make compost tea?

Making compost tea is a fast process that lasts between 24 and 36 hours. A slightly longer brew will increase the amount of beneficial microbes, but you should not brew the tea for longer than three days. Doing so will cause the microbes to die out for lack of food supply. One benchmark to know if the brew is fresh and effective is that it will emit an earthy fragrance. Some gardeners claim that compost tea will stay fresh in the refrigerator for up to 30 days, but there is no reason to keep it on hand this long if you’re ready to apply the treatment.

Apply compost tea on sunny mornings when the plant stoma are most open to receiving and absorbing the mixture. A rule of thumb is to do it when dew conditions are favorable, so if you don’t have time to apply the tea early in the morning, do it at dusk.

How do you make compost tea to enhance your cannabis harvest? Here is an easy compost tea recipe, complete with all the necessary steps and ingredients.

What is the best compost tea recipe?

To whip up the best compost tea to strengthen your cannabis plants and make them more resilient, you’ll need five main ingredients:

  • Compost: The first and most important ingredient is compost with a rich biome of nutrients and microorganisms. The more developed the compost’s fungal colonies, the stronger the compost tea will be. Organic compost from local sources provides the best foundation for this recipe.
  • Kelp: This sea ingredient feeds the fungal colonies and aids in development, ultimately activating the potency of compost tea.
  • Molasses: More commonly used as an ingredient in baking, molasses feeds the helpful bacteria, encouraging them to proliferate and maximize the benefits of compost tea. For an extra infusion of potency, try blackstrap molasses, which is saltier and more bitter than the ordinary kind, making it better for brewing compost.
  • Worm Castings: Though not the most appetizing ingredient, worm castings are dense in easily absorbed nutrients and introduce a host of microorganisms to the tea.
  • Fish Hydrolysate: Like kelp, fish hydrolysate feeds fungi, but it also contains nitrogen and chitin, the latter of which serves as an immune booster to marijuana plants.

Once you’ve gathered these ingredients, you’ll need a few supplies before the tea brewing begins.

What you need to make compost tea

This simple compost tea recipe doesn’t require many supplies in addition to the main ingredients. You’ll just need:

  • Non-chlorinated water. It can be tap water that sits for 24 hours or, for a really organic experience, rainwater.
  • 5-gallon bucket, though larger gardens may need a larger size.
  • Watering can or spritzer.

In addition, if you would like to aerate the compost, which is recommended, you will need:

  • Air pump.
  • Aquarium bubbler.
  • 400-micron mesh bag or breathable fabric, such as pantyhose or any porous cloth.

The aquarium bubbler, kelp, and fish hydrolysate can all be purchased at a fish or aquarium supply store.

Steps to making compost tea

The three steps to making compost tea are straightforward:

  • Build the brewer: Place the aquarium bubbler in the bottom of the bucket and use plastic tubing to attach it to the air pump outside the bucket. Fill the bucket with non-chlorinated water.
  • Fill the teabag (aka the mesh bag): Remove any worms from the compost before you proceed with this step. Then, pour the tea ingredients into the mesh bag.
  • Brew the tea: Carve out at least a 24-hour period to let the pump run continuously and brew the tea. Be prepared to apply the compost tea to the soil as soon as possible, preferably within 36 hours of adding the bag to the brewer.

There is an optional fourth step. You can supplement the compost tea with items in addition to the kelp, molasses, and castings. Try a biologically active product such as Actinovate along with supplemental food for fungi and bacteria, if desired.

Once the compost tea has brewed, apply it to the soil. You can also spray some of the mixture onto the leaves for a more thorough treatment. This usage varies from plain compost, which is applied only to the soil and doesn’t directly reach every part of the plant . Foliar spraying is one benefit of compost tea, offering a more well-rounded treatment than might otherwise be possible.

Can you burn your plants with compost tea?

It is possible to burn plants with compost tea, especially if you are using a compost high in nitrogen. Manure-based composts tend to contain higher levels of nitrogen, so be sparing as you treat the soil if you are using this type and don’t spray it on the leaves. Otherwise, you can be more liberal in your treatment of the soil, especially since compost tea loses much of its potency within a few hours of brewing and long-term storage is not feasible.

Bottom line on compost tea

Compost tea is relatively easy and inexpensive to make. But it has a very short shelf-life and needs to be applied to the soil immediately to enrich the health of cannabis plants.

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