Worm Castings: Best For Cannabis Growth

Worm castings are an organic soil amendment made up of earthworm droppings, which recycle organic material from the soil. They provide substances that promote cannabis growth, more than any other natural product. Worm castings are the best option for beginners and the most reliable for everyone. 

What Exactly Are Worm Castings?

Worm castings are the dried manure of worms. Unlike the manure of farm animals, castings are ready to use immediately.

As worms live in the soil, they eat tiny organisms and bits of organic material, that are then taken apart in their digestive system. 

When it exits, it has converted into a perfect blend of benefits. Then, the microbial life included in worm castings, converts nutrients into plant-available forms. 

Worm castings in hand
Worm castings are a great source of nitrogen and microorganisms

This is called vermicomposting, and is the process of using worms  to convert organic wastes into this humus-like material.

Worm castings are the richest organic and natural fertilizer in the market today. In cannabis they're perfect to start you off on the right path, and it can help with cannabis nitrogen deficiency (learn how to correct a nitrogen deficiency in marijuana). Add worm castings once and you can provide enough benefits to feed your cannabis plant for up to two months.

Castings should be mandatory in every grower's soil.

Commercial worm castings
Wiggle worm castings

How To Use Worm Castings?

So what’s the best way to get worm castings benefits activate in your soil? Depending if you're growing in indoors, in a garden, or mixing your own soil, you have different options.

Worm Casting Tea

worm-castings-teaIf your substrate does not have humus, or not enough, the easiest way to feed your plants is making worm casting tea. You’ll be steeping the castings in the water, like you would with a tea.

  1. Fill a bunch of containers with water, and leave those open for at least 24 hours, so it'll get clean of chlorine and other substances.
  2. Find a porous fabric, like an old sock, an old t-shirt or a pillowcase you don’t need.  
  3. Now, for every liter of water add 3-4 tablespoons of worm castings inside the fabric, and close it by tying knots in it.
  4. Once again let it stand in an open container for 2 to 3 days.
  5. The water will turn into a dark brown tea when it’s ready.

You can now use this tea to water your plants and give them all the benefits that worm castings bring to the soil.

PS: If you strain it, you can also use it as a foliar application.

When To Use Worm Tea?

You want to use the tea when you need your plant to get a good boost!

If your plants are looking less vigorous, or the lower leaves are starting to discolor, a good shot of worm tea will boost them up.

But if your plants are showing growth problems, (like a serious nitrogen deficiency), you need to complement by adding it into your soil.

Top Dressing

The easiest way is to use the worm castings as a top dressing. You might guess from the name, but this method is when you add them to the top of the soil around your plant. 

  • Add ½ to one inch of worm castings on top of the soil and around the base of your plant.
  • Extend the castings two or three inches away.
  • Make sure to water your plants after applying the worm castings.

Then you can replenish with extra castings once a month to reload nutrients and stimulate beneficial activity. 

 You can use this method this with potted and as well as garden plants.  

Side Dressing

For side dressing you place a small handful of castings at the base of the plant. 

Then rake or work it into the earth, very shallow so you don't damage the roots. Water thoroughly!

Amending Your Soil

If you're preparing your own soil, worm castings are a MUST in your mix, as it will provide a great environment for your seedlings and younger plants.   

You want to add at least 10% of worm castings to your soil. And then work it through the soil to evenly distribute the castings. 

If you need more info here's a guide on how to prepare the perfect soil.

Spreading In Larger Outdoor Areas 

Worm castings are great for outdoors, too! But adding them on an existing area takes preparation.

Before you can begin, you need to screen your castings to break up large particles. 

You'll have to run them through fine sifter, which wll also remove any larger material that might be mixed into the castings.

Be very careful not to dry it out, as this process will remove moisture from the mix. 

You can now use a fertilizer spreader to scatter them. 

You’ll want at least five pounds of screened castings for each 100 square feet of lawn. 

Seed Starting And Transplanting

When starting seeds, use a little more castings than you would on established plants. I recommend one part castings to every two parts of your soil mix.

This worm casting soil mix will provide protection for young seedling plants.

When transplanting your plants into the garden, add a handful in the soil under the roots. This will provide a quick boost for your cannabis plants and long term protection. 

Benefits That Worm Castings Bring To The Soil

If you're looking for a rich source of essential nutrients for your cannabis plants, earthworm castings are a great option. They contain water-soluble plant nutrients such as nitrogen, phosphorus, and potassium, as well as calcium, iron, and sulfur, all of which are vital for healthy growth. To learn more about the essential nutrients your cannabis plants need, check out our article on Essential Nutrients for Cannabis.

Additionally, earthworm castings contain more than 50% more humus than what you typically find in topsoil, along with desirable microorganisms that can further promote healthy plant growth.

Brut worm castings
Brut worm castings

NPK Levels In Worm Castings

Worm castings contain important macronutrients for cannabis plant growth, including nitrogen, phosphorus, and potassium (N-P-K rating: 1-0-0). To learn more about the role of these macronutrients in cannabis plant growth, check out my comprehensive guide to Macronutrients.

Although the N-P-K rating may seem low, the nutrients in worm castings are highly accessible to cannabis plants and have been shown to enhance seed germination, plant growth, and even bud production. In addition to N-P-K, worm castings also contain other essential nutrients like calcium, iron, and sulfur, as well as beneficial bacteria and microbes that help create a living soil. 

Other Nutrients In Worm Castings

There are many nutrients that cannabis plants need to stay healthy and thrive. Worm castings contain low amounts of most essential nutrients that are guaranteed to not cause nutrient burn. 

Analysis of worm castings shows that they not only contain nitrogen, phosphorus and potassium, but also calcium, iron, and sulfur.

Soil Structure

Soil structure improves when adding worm castings into the mix.

Worm castings improve soil aeration, which is greatly benefitial for the root system.

There's also an increase water retention, keeping the soil moist for longer periods of time allows for a better absortion.

Worm castings will "fix" the nutrients, preventing plants from taking more than they need. It also anchors nutrients so that they not flush away with water.

If you're growing outdoors it will attract new earthworms already living in the soil, which will keep the cycle going.

Beneficial Microorganisms

Worm castings contain beneficial bacteria and microbes that are added by the worm in it’s digestive process and are very active in worm castings. These feed from organic matter to produce, store and slowly release plant nutrition.   

The microbes and beneficial bacteria help create a living soil. They live around the roots of the plant, protecting them, and providing the perfect atmosphere for vigorous plant growth.

Soil microorganisms
Soil microorganisms

Protects Against Diseases And Pests

The humus in the worm castings extracts toxins and harmful fungi and bacteria from the soil. Thus have the ability to fight off plant diseases, as the researchers at Cornell demonstrated

Also, castings degrade the protective covering of some insect pests, and inhibits mites, aphids and mealy bugs.

Balanced PH

The chemical changes that the organic wastes undergo include deodorizing and neutralizing. 

This means that the pH of the castings is 7 (neutral).

Worm castings act as a barrier to help plants grow in soil where the pH levels are too high or too low. They prevent extreme pH levels from making it impossible for plants to absorb nutrients from the soil.

Organic plant wastes usually have a carbon-nitrogen ratio of more than 20 to 1. Because of this ratio, the nitrogen is unavailable to plants, and the soil around the organic waste becomes acidic.  

Worm castings reduce the acid-forming carbon in the soil, and increase the nitrogen levels in a state that cannabis plants can use.

Final Thoughts On Worm Castings

Using worm castings regularly will promote well developed root systems and vigorous plant growth. And are definitely the best organic food for cannabis growth and development.

Hey there, I'm the person behind this website. I started growing cannabis in 2014 right after marijuana was legalized in my home country. Today, on drcannabis.io, I address growers need for knowledge and show you how to grow cannabis plants and enjoy amazing buds.

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