Build Perfect Organic Soil for Cannabis With These 4 Steps

Growing cannabis organically allows growers to raise a high-quality product without the interference of chemical nutrients that can burn or kill the plants. To create a soil that provides the perfect environment, you’ll need a basic primer on how best to work with it and what nutrients are required to help your plants thrive.

There’s a large industry behind pre-mixed soils that all have something to offer in terms of convenience, but they can be expensive while lacking levels of specific nutrients you might want for your cannabis plants. For this reason, it’s important to truly understand what you want in your soil so that you can produce your own custom blend that costs less and contains all essential nutrients.


What Are the Best Nutrients for Growing Cannabis?

Follow these steps to better understand what makes ideal soil and how to build it in your own cannabis garden.

Step 1: Know What’s in Your Soil

Know what's in your soil(dogayusufdokdok/iStock)

To build a quality soil, you first need to know what’s in it to begin with. When buying soil, you’ll see a list of ingredients and information on what nutrients are readily available in it. If you’re hoping to use soil that is already in your garden or being taken from another source, it’s impossible to readily know what is actually in that soil. To remedy this problem, you can submit a soil test that will give you a base understanding of what nutrients it contains.


Growing Organic Cannabis at Home

Additionally, you can work your hands through the soil and get to know it. Is it compact or fluffy? Is it sandy or claylike? Does it hold moisture or is it dry? Are there worms and insects present? These are all things you can consider by simply using sight and touch.

Step 2: Find the Right Soil Amendments

Chicken manure(eyewave/iStock)

Once you’ve gotten to know your soil’s nutrient levels and texture, it’s time to add any necessary soil amendments. The basic building blocks for plants are based around N-P-K. This stands for nitrogen (N), phosphorus (P), and potassium (K). To build a strong healthy soil, it should have these nutrients readily available for your plants to absorb.

Nitrogen-Rich Nutrients:

1. Worm Castings

Providing a quick-release source of nitrogen for your plants while also introducing healthy bacteria, worm castings contain many micronutrients depending on where they are sourced from.

2. Crustacean Meal

A little slower to release than worm castings, crustacean meal adds nitrogen, phosphorus, calcium, and chitin to your soil. Chitin-eating microbes will help keep nematodes at bay.

3. Bat Guano

Bat guano provides the highest levels of nitrogen and phosphorus of all these listed nitrogen amendments. It does wonders for sustained plant growth while diversifying the soil’s bacteria and microbes.


Spider Mites, Fungus Gnats, and Root Aphids: How to Deal With 3 Common Cannabis Pests

Phosphorus-Rich Nutrients:

1. Bone Meal

Bone meal generally comes from cattle bones, and it helps to keep phosphorus levels up. Keep in mind that your soil needs to be at a pH below 7 for bone meal to be most effective.

2. Chicken Manure

Chicken manure is a great way to introduce both phosphorus and nitrogen. Choose a high-quality manure that is fully processed and make sure to amend the manure into your soil with enough time to let hot manure cool off.

3. Rock Dust

Rock dust is a very slow-releasing phosphorus source that can be effective in soil for years, but it does not perform well in soils with a pH above 7.


How to Prevent Root Rot, Mildew, and Leaf Septoria on Cannabis Plants

Potassium-Rich Nutrients:

1. Kelp Meal

Kelp meal is a great source of potassium that promotes microbial diversity in the soil. A water-soluble amendment, kelp can be applied with water or by hand directly into the soil.

2. Wood Ash

Wood ash can be used to increase the potassium levels in your soil, but be aware that it generally raises the pH so make sure to test your soil’s pH levels regularly.

3. Compost

Your compost bin can be an excellent source of potassium for your garden, especially if it contains fruit rinds and banana peels.


How to Make Compost Tea for Cannabis Plants

These three basic N-P-K amendments are most important, but there are also micronutrients that will help your plants grow. Products like gypsum, azomite, and kelp meal can add many micronutrients to strengthen your soil. When it comes to soil, a wide diversity of nutrients can introduce nuanced flavors, aromas, and effects in your end product.

You should also consider amendments that change the soil’s density, airflow, and ability to hold water. For example, perlite and peat moss can improve drainage and water retention. Introducing a healthy worm population and fungal colonies will also help fluff up the soil, thus improving its structure. A healthy soil maintains itself, and living organisms both reap and share the benefits of a healthy soil with your cannabis plants.

Step 3: Mix Your Soil

Soil tiller(bondarillia/iStock)

To till your soil, apply the amendments and start digging or use a rototiller. It takes time, but make sure everything is adequately mixed and that all corners of the pot or bed have been reached.

Once you’ve mixed everything in, water your soil to help cool any added manure. This process should be repeated every few days until the soil is cool to the touch when you bury your hand. At this point, the soil is ready for your seeds or clones.

Though tilling your soil is necessary for your first year as a gardener, it’s up for debate whether or not tilling annually is beneficial. The argument against tilling is that it breaks down a complex network of mycelium, worm tunnels, and cavities created by beneficial organisms in the soil. However, by tilling your soil annually, you can easily add amendments and break down cover crops, thus making sure all the nutrients in the soil are mixed and readily available.


How No Till Cannabis Farming Methods Can Improve Your Crop

Still not sure whether to till or not to till? Try analyzing soil samples at the beginning and end of the season to determine whether or not annual tilling benefitted your garden in the end.

Step 4: Prepare Your Soil for the Next Season

Growing radishes(fstop123/iStock)

To protect your soil for the next season, remove the stalks and roots of the previous cannabis plants; you can compost and re-apply them to your soils once they’ve decomposed.

Next, introduce a cover crop to your soil to help maintain it during winter. Common crops include legumes or radishes. Legumes sequester and preserve nitrogen while radishes have long taproots that help aerate and free up deep, compacted soils. These cover crops need to be destroyed before they go to seed. This can be accomplished by tilling or cover mowing to kill the plants.


Organic vs. Chemical Cannabis Fertilizers for Your Grow

In the offseason, you can add nutrients back to your garden by top dressing the soil. Adding compost, manure, and other amendments and allowing rainfall to bring the nutrients into the soil is a great way to improve the soil quality in the offseason without having to do much work.

Building your own soil is a rewarding investment that will only strengthen your understanding of gardening and how plants grow and thrive. With quality soil, you will find the need for liquid feeding to be greatly reduced, saving you time and money. You’ll also find that the soil becomes a sanctuary for other living things as you improve the environment surrounding your garden.

Soil is unbelievably diverse and complex, and we still have much to learn about how to cultivate it to perfection. If you have any personal experiences with building perfect soil, chime in by leaving a comment below.

Leave a Reply