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In your search for the best fertilizer for marijuana, there's a good chance you've heard about worm castings. Worm manure is often overlooked, but it has proven to be one of the most potent soil supplements in the marijuana industry. What exactly makes worm castings such a popular marijuana plant food? Let's get the dirt on worm castings.

Using Worm Castings to Grow Marijuana

worm casting fertilizer for marijuana

Earthworm castings are "growing" in popularity in the marijuana community (you see what I did there?). With weed being legalized either for recreational or medicinal use in many states, marijuana farms are sprouting up everywhere.

One of the biggest challenges they face is trying to identify the perfect marijuana plant food. While it's often been overlooked, because it's somewhat difficult to find, worm castings are proving to be the ideal soil supplement for marijuana growers.

"If you're growing plants or for any garden, these worm castings are a absolute must have! I will not get castings from anywhere else, the team at Simple Grow and their product blows away all others!"

R. Adams

Verified Purchase


Many growers have found that it shortens the germination cycle for new plants, increases yield on their crop overall, and does it all while protecting the plants from disease. As if that wasn't enough, worm castings are also chemical-free. This makes it an especially attractive option for organic growers, specifically. 

You should also read our post on best soil for marijuana.


Faster Growth and Higher Yield

The legalization of marijuana has shown just how much of a booming business that marijuana cultivation can be. With it being one of the most profitable cash crops on the market, a lot of farmers are giving it a second look.

The fertilizer that you choose can have a major impact on the bottom line for marijuana farmers. Ultimately, you want to grow more marijuana and you want to do it faster. By maximizing production, you can create more product and do it more profitably. 

An Ohio State University study found that worm castings have a substantial effect on the yield of crops. They found that increased yield was due to plant growth regulators produced by microorganisms within the castings. In short, the castings have billions of tiny, healthy bacteria within them that contribute to the rapid germination and growth of plants.


...several times higher in nitrogen, phosphorus, potassium, and magnesium than topsoil.


In addition to the beneficial microbes, the USDA says that worm castings are "several times higher in nitrogen, phosphorus, potassium, and magnesium than topsoil." The nutrients in all-natural worm castings are substantial and they provide the perfect mix that marijuana plants need. 

The bottom line is that worm castings mixed in with your soil will pay big dividends when it comes to harvesting marijuana. 

Protects Marijuana Plants Naturally

Worm castings have the ability to protect your marijuana plants from both diseases and pests without the use of harmful chemicals. This study from Cornell University found that earthworm castings can stop many common plant diseases.

According to the study, castings "can colonize a seed's surface and protect it from infection by releasing a substance that interferes with the chemical signaling between the host and the pathogen." These pathogens are a common issue for many greenhouse growers when attempting to grow marijuana and other plants indoors.

Worm castings help form a protective barrier at the microbial level, that will keep your plants growing even if they're exposed to potentially harmful diseases.

In addition to protecting against disease, castings also help keep pests at bay. Microbes in worm castings naturally stimulate the production of chitinase, which breaks down the exoskeletons of many insects.

This provides a natural and safe form of pesticide without all the synthetic chemicals. You can save money on pesticide, while at the same time keeping your plants healthy for consumption.

A Little Goes a Long Way

When being cost-conscious, you don't want to spend to much on fertilizer or soil supplement. If you're in need of a cost-effective solution, worm castings are the way to go. While you really can't use too much, you don't have to overdo it either. If you have a large agricultural, landscaping, lawn care or gardening business, buying worm castings in bulk is more cost-effective and convenient for you.

At Simple Grow, we guarantee a high-quality product every time and we can have your order delivered right at your doorstep. Contact us now so we can give you a free custom quote.

Many growers use a mix of 25% earthworm castings to 75% soil. That's typically enough to make a big difference for the plants. In some cases, growers make an earthworm castings tea by soaking the castings in water and then spraying the plants with the mixture. This allows you to get even more bang for your buck and help your marijuana plants throughout the growth cycle. 

Another nice thing about worm castings is that you really can't screw it up. If you put too much in the soil, it's not going to burn the plants. It's totally safe to handle and it won't have any negative affect on the plants if you accidentally put too much in.

In fact, you could grow marijuana plants directly in worm castings if you wanted to, although it's probably not the most cost-effective route to do it on a large scale. If you try worm castings on your marijuana plants, you can tweak the mix to get just the right formula. The good news is that it'll work well, regardless of what you do.

Choosing the Right Worm Castings Product

With as awesome as worm castings are, you might think that you'll be fine no matter which one you buy. While worm castings are great in general, not all brands are created equally. What are some things that you should look for when buying the best fertilizer for marijuana? 

  • Percentage of purity
  • High-quality food source for the worms
  • Controlled process that ensures quality castings
  • Guaranteed results
  • Trusted brand

Simple Grow Soil Builder is the highest-quality worm casting product on the market. We offer various size bags of worm castings to cover whatever size planting area you have.  Needing more than 1 ton?  Click here for a free bulk quote!



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Are Worm Castings the Best Fertilizer for Marijauna



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