If you’re a novice or relatively new to the world of marijuana cultivation, knowing the best soil to use can seem like a daunting task. Although weed can be grown in a lot of different kinds of soils, it needs the proper balance of different variables for your plants to fully thrive and produce abundant trichomes, THC, CBD, and other cannabinoids. If you are going to buy potting soil from a store then most of these variables are already taken care of.
However, if you’re wanting to make your own organic soil, there are several things to be aware of, which is why we are writing this (hopefully, helpful) post on how to cultivate the best soil for marijuana plants. Optimal soil conditions help your plants grow to their maximum potential, which means a higher yield and more bud overall.
Soil for Marijuana Plants — Variables to Consider
All of the items listed below are some of the most important components for choosing the right soil for marijuana plants.
- Texture: weed will grow best in light and loose soil as this makes it possible for more oxygen to reach the roots, which then works to ensure the maximum growth and health of your plants
- Good drainage and good water retention: if your soil doesn’t have excellent drainage then your plants could either get sick, produce meager yields, or even die. At the same time if your soil can’t retain any water, then you’ll also end up with unhealthy plants that could easily die.
- Nutrients: maintaining the right nitrogen to phosphorus to potassium ratios. For more in-depth info on this, check out our blog on soil nutrients here.
- Correct pH levels: the ideal pH for cannabis soil is 6, but if you’re in the 5.8-6.3 range you should be fine.
Types of Natural Soils
There are four kinds of natural (outdoor) soil: sandy, silty, clay, and loamy–all of which can appear as any kind of combination from sandy/clay to loamy/sandy to silty/loamy/sandy, and so on. In short, sandy soil has good drainage but poor water retention. As such, when sandy soil is watered its nutrients can get washed away. However, it is easy to work with and has high oxygen levels due to being loose in structure.
Silty soil is rich in minerals and nutrients, has good water retention, and is considered to be quite fertile. However, its drainage is only so-so at best. Clay, which is high in pH, has strong water retention and is incredibly rich in both nutrients and minerals, which is why many use it for organic growing. Nonetheless, its disadvantages are that it has very poor drainage and is very hard to work with due in large part to how heavy and dense it is.
Loamy soil is a combination of all three soils listed above along with additional organic materials. It offers incredible water retention and drainage, has high oxygen levels, and is nutrient-rich. In fact, it is considered one of the very best types of soil for marijuana plants. Its only real downside is that loamy soil can be expensive to purchase.
Regardless of if you are using sandy, silty, clay, loamy soil, or any combo thereof, you will most likely need to improve its quality by adding amendments. For example, adding something like coco fiber to sandy soil, which has great drainage but poor water retention will help improve its ability to retain water. Provided below are a few of the many amendments you might want to buy from your local nursery to add to your soil in order to give it that extra boost it needs.
- Coco Coir: as mentioned in the example above, coco coir, aka “coco fiber,” provides water retention and can also be used to loosen up more compact soils. In general, and depending on the exact composition of your soil, adding up to 30% of coco coir should do the trick.
- Perlite: these light, white rocks work to improve both drainage and airiness. Starting with 10-15% perlite should be good as if you use too much your soil may lose its nutrients due to the soil becoming too “light.” While its water retention is fair, perlite is definitely one to use for increasing drainage.
- Vermiculite: now if you’re wanting to improve your soil’s ability to retain water, vermiculite, which also increases the soil’s airiness, is what you want to choose. Using about 10% vermiculite is a good place to start. It can be used in conjunction with perlite.
- Nutrients: Maintaining your soil’s nutrient levels is incredibly important. If you aren’t using store-bought soil, there’s a chance that you won’t need to add more nutrients if your soil is already rich in organic materials. If you do need to add more nutrients you can either make your own compost–do not just throw vegetable scraps directly into your cannabis soil–or simply buy a bottle of nutrients for your plant’s growth and/or flowering stage.
Note that while some use worm castings to enrich their soil, they also come with other benefits such as improving the drainage, water retention, and texture of the soil. While this definitely does not cover every single variable and amendment that exists for cultivating the best growing soil for marijuana plants, hopefully, this all serves as an easy reference guide to get you started!
Written By Kim Thompson
Along with being an award-winning creative and literary writer, Kim works as a freelance copywriter, editor, and proofreader both domestically and internationally.
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