Best Soil Mixes for Cannabis

High-quality cannabis doesn’t require a chemical-saturated growing medium; some of the best soil mixes for cannabis can be made from scratch.

Equally important to consider is that some of the best soil options for marijuana plants can be bought in a shop. However, if you’re not mixing your own soil, you’ll need to ensure the brand uses the quality ingredients you need for each stage of your cultivation operation.

Contrary to popular belief, the best organic cannabis doesn’t come from a hydroponics system. Instead, it involves balancing nutrients to ensure your plants are properly fed.

In this post, we cover what to look for in the best soil mixes for cannabis cultivators. Whether it’s your first time growing or you’re cultivating at the commercial level, keep this information in mind the next time it’s time to create or purchase your medium.

best soil mixes for cannabis

What to Look for in Quality Cannabis Soil

Soil Texture

Cannabis plants enjoy a light, loose soil texture. The light texture allows for adequate root development. But it also encourages more oxygen to the roots, enabling optimized plant growth and health.

Soil pH

Soil pH levels should fall at around 6.0. Ideally, it should fall between 5.8 and 6.3 to maintain optimal growing conditions. If the pH level is a little low or high, your plants may experience lower yields. And if the pH is way off, the plants will die.

Drainage Ability

Excellent drainage prevents overwatering. It also prevents puddles from forming on the surface of your soil mix after it rains or you water. You’ll have to learn how to calibrate your watering system to account for drainage. But ensuring adequate drainage will keep your plants from getting sick, yielding poorly, and dying.

Water Retention

On the other hand, soil that doesn’t hold water well won’t provide your plants with the water they need. The soil will be dry, causing it to shrink. Drainage is important, but so is water retention.

Nutrients

Cannabis plants thrive with the right nutrition. Most soils will have nutrients in them already. However, you should know that the nutrition usually only lasts for three to four weeks. Depending on the plants, this could be around when the plants will begin the flowering stage. Make sure to add nutrients at this time if this is the case for you.

Best Soil for Growing Cannabis

Loamy Soil

Loamy soil is likely the best for cannabis. Albeit, this soil is quite pricy. But it offers impressive results.

With this soil, cannabis cultivators have sand, silt, and clay soils with additional organic compounds. It provides excellent water retention and drainage and contains plenty of nutrients and oxygen.

Clay Soil

Organic growers will want to look at using clay soil. This contains fine mineral particles, and while it’s heavy and challenging to work with, it has lots of the nutrients and minerals organic cannabis grows crave.

While clay soil offers excellent water retention, its drainage is quite poor. Keep this in mind if you’re considering using clay soil for your grow.

Silty Soil

Silty soil is also a good option for organic grows. This soil is a medium-coarse soil type that contains plenty of minerals and organic particles that contribute to cannabis growth.

Silty soil is quite easy to work with and offers good water retention. It also offers adequate drainage. As one of the most fertile soil types, it’s no wonder why so many cannabis growers incorporate it in their operation.

Sandy Soil

Sandy soil is the simplest option if you’re not an organic grower. It provides excellent drainage and very few nutrients. But with poor water retention, key nutrients like nitrogen get washed away quickly.

This soil is quite easy to work with. But keep in mind, you’ll need to water more frequently and add nutrients to make up for those lost.

Best Soil Mix for Homegrown Cannabis

If you’re growing cannabis at home, there are some things you can add to your mix to improve it. Natural soil isn’t always great for cannabis plants. The texture might be off, but here’s what you can add to encourage healthy plants:

Coco Coir

Coco coir is a great addition to your soil mix. It’s made from coconut husks, and these light coconut husk fibers offer fantastic water retention while lightening compact soil. Some growers incorporate coco substrate with some other nutrients for cannabis cultivation. However, to improve existing soil, some cultivators add up to 30% coco coir.

Clay Pebbles

Clay pebbles are ideal for use as a component in a hydroponic setup. However, it’s also excellent for improving soil structure. While it won’t add any nutrient value to your plants, this material is good for the bottom of raised beds and containers because it prevents water buildup at the base of your plants. This minimizes the chances of root rot.

Clay pebbles are also good for the top of containers to act as mulch. These pebbles keep moisture in the growing medium by minimizing evaporation.

This clay pebble mulch offers some shade to the top layer of your growing medium. But it also suppresses weeds and keeps beneficial microbes out of direct sunlight, allowing them to thrive with your plants.

Perlite

Growers globally use perlite to enhance the soil. This stuff is composed of light, bright-white rocks that help with drainage and the airiness of soil. But it’s also good for water retention.

For those interested in amending soil with perlite, you’ll need to add around 10 to 15 percent of perlite to it. While you can put additional perlite, this could make the soil too airy, allowing the nutrients to leach out of it. Most good-quality commercial soils include some perlite.

Worm Castings

Worm castings are an excellent organic amendment for soil. It has more than just nitrogen and phosphorus too; worm castings contain beneficial microbes that break down elements in the soil to help plants grow.

Adding this stuff to your mix can improve its structure and act as a microbial catalyst. Worm castings are also excellent for retaining water in the soil.

If you decide to amend your soil with worm castings, it’s best to use between 25 and 30 percent. This should improve the drainage, water retention, and texture of the soil.

Vermiculite

Similar to perlite, vermiculite is a heat-treated mineral growers use to lighten their soil. This stuff is great for retaining water, too.

However, while vermiculite is similar to perlite, they offer opposing benefits. Perlite increases drainage and airiness. But you’ll use vermiculite to improve water retention.

The fact that vermiculite and perlite work well together means you can use them to improve your soil with ease. Most of the time, growers will use around 10% vermiculite in their soil composition.

Concluding on Best Soil Mixes for Cannabis

The best soil mix for your garden depends on your growing method. If you plan to grow in the ground, it’s ideal to look for a good quality commercial potting mix with some amendments like perlite and worm castings.

As an alternative, using store-bought organic mixes is also great; however, they may not be heavy enough for outdoor growing.

Consider adding some organic components to your mix. This should improve the soil’s texture and promote healthy cannabis plants.

What’s your favorite soil mix? Let us know in the comments below!

Author:
Louis Levey is the Content Success Manager and Founder at No Strings Content. He's passionate about helping cannabis businesses use content to attract, educate, and convert audiences. His hometown is Boca Raton, Florida, but he currently lives and works remotely in Chiang Mai, Thailand.

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