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The Importance of Good Soil for Cannabis and How to Mix it up!

When most of us think of soil, we think dirt. But the truth is nothing is as essential for plants than the substrate it is growing in – the same is true for cannabis. 

There are three critical elements for soil, which are:

  • Texture;
  • Drainage ability;
  • And water retention.

These elements can change depending on where and how you’re growing your plant. Climate is a huge contributor, whether in the hot and dry climate of the Northern Cape, the humid Kwa-Zulu Natal, and the Mediterranean climate of the Western Cape. 

While everyone will talk about nutrients for their cannabis plants, without the right texture, it means nothing. The composition will determine how the soil drains and its ability to hold onto water. 

Your soil shouldn’t be too compacted and clumpy; it should be relatively loose. If you can’t dig into the earth with your finger, it’s too dense. Roots need to be able to access oxygen, without which they will eventually shrivel up and die. 

Loose soil also allows for water to seep to the roots. But there is a balance that needs to be found and maintained. Too much water and the roots drown, too little and the roots dry out and die.  

This balancing act can be achieved with ease and can change with climate and growing environment. But as a rule of thumb, the signs that your soil is suitable for cannabis are: 

  • Appears dark, think dark coffee brown not strong tea; 
  • Has loose texture, should flow through the fingers like rice;
  • Drains well, you’ll only discover this when it comes to watering, but the water shouldn’t pool at the top;
  • And finally the soil should hold water without getting muddy. While cute for washing powder adverts, you want wet soul, not clumpy mud. 

As mentioned above, there is a balance you need to achieve. While you can walk into a nursery and buy a regular bag of potting soil, it’s far from what is optimal for growing cannabis. 

To achieve that perfect balance, here are a few natural additives to mix into your soil to ensure that your plants get the best treatment. 


A favourite additive for growers is perlite. Most horticulturists will automatically mix this into their soil. You might know it from more traditional gardens as the popcorn rock-looking substance.  

It’s also versatile. If added in small qualities, it helps the soil retain water better, so it’s perfect for sunny and hot balcony growers, where pots can dry out quickly. 

For those who want to grow plants with a large head,  adding a higher level of perlite will be a huge nutrient boost. Also, perlite helps with drainage, so if you were growing in a waterlogged area in the garden, this would help too. 

Other water retaining additives include vermiculite, coco coir (coconut husks), and peat moss. They all have slightly different positive attributes. Just remember to plan for your grow area. 

Earthworm Castings

One little creature all growers should love are earthworms. Earthworm castings is a polite way of selling, well… worm poop, but it’s so good for plants because of its high nutrient density. Also, it helps improves the drainage and moisture retention of the soil. 

Another benefit is it adds good micro-organisms to the soil in a natural way, so everyone is happy. 


There are a million and one different natural nutrient additives to mix in with soil. From bat guano (yes you read that right), bone meal, and some compost teas (this can be bokashi or worm tea). While you shouldn’t throw all of these additives in at once, it’s best to choose one that compliments your plant’s surroundings.

If you remember these basics, you should be well on your way to growing a great plant. And to be honest, most of these tips would work with nearly any other plant, so maybe share some tips with your grandparents.   

Zootly says: If you want to grow good bud. Look after your soil and your plant will take care of its self.

Words By: Andrew Macfarlane, writer and budding horticulturist.

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