Best Soil for Growing Weed

Best Soil for Growing Weed

Soil is one of the most vital components in growing cannabis, whether you want to call it growth medium or dirt. Picking the best soil for growing marijuana is probably the most crucial choice you would make when growing marijuana at home. Getting it on point is probably the difference between a complete failure and an abundant harvest. The obvious simplicity of soil harvesting sometimes fools newbies, sometimes making mistakes cost their harvest. In fact, it causes a lot of concern. For instance, the soil you use to grow indoors isn’t the same soil you need to grow outdoors. Then there are minor things like drainage, pH, and a variety of other requirements. A huge number of soil brands are obtainable in the market, and it is both good and bad news. You’ve got a lot of choices. But with so many options, what soil is best for growing weed? The best approach here is to evaluate your situation, and this guide would help you the rest. Enjoy reading!

What is the best soil for growing marijuana?

Not all solid is suitable for growing marijuana, and not all marijuana needs the same type of soil. Choosing the ideal soil is based on the kind of marijuana you are going to cultivate, the climate, whether you are going indoors or outdoors. 

Apart from these aspects, there are some common characteristics among all marijuana soil. Below is the break down of the characteristics for the best soil for cannabis:

  • Texture – marijuana plants prefer a loose and light soil texture. A soil with a light texture encourages root development, and it makes sure more oxygen gets to the root for ideal health and growth. 
  • Drainage – a good growing medium for weeds is soil with excellent drainage. Because once you water your cannabis plants, it should not pool on top of it. And if the soil has low drainage, your marijuana plants would probably get sick and would produce substandard yield, or worse they would die. 
  • Water retention – just like the importance of good drainage, water retention is important too, this is the ability of the soil to hold water. Good growing medium soil for marijuana has an optimum balance of water retention and good drainage. 
  • pH value – is it the chemical spectrum that signifies how alkaline or acidic something is. This is necessary because marijuana only works well within a small pH. The best soil for growing marijuana outdoors and indoors has a pH of around 6.0. A pH of 6.8 – 6.3 is enough, but if it increases too from outside this range, your yield will reduce. But if the pH is extremely off, your marijuana plants will. 
  • Nutrients – the best soil for cannabis need to have nutrients so that plants can thrive. Luckily, most of the soil you can buy at any brand has them. However, you must know that these nutrients would sometimes last only for 3 to 4 weeks. Around this time your cannabis plant begins to flower, the nutrients in commercial cannabis soil would probably be exhausted. This is when you begin to add more nutrients. If you grow without enough nutrients added, your cannabis soil needs to have organic substances like compost, humus, guano, worm castings, and a lot more. Microbes in all the soil would turn these materials into nutrients for your cannabis plant to get what it needs. 

Characteristics of a Quality Marijuana Soil

If you bought potting mix soil from the store, these are probably already “tuned” for growing. Growing organically is a different story, though. Organic soil compost of four different varieties; loamy, sandy, clay, and silty. But you must know that most of the soils consist of varying ratios of these kinds of soil.


Loamy soil is a mixture of clay, silt, and sand with some added natural compounds. It’s one of the best soil for growing marijuana indoors and outdoors because it provides excellent drainage and optimum water retention, and it is rich in oxygen and nutrients. The negative side here is, this type of soil could be costly. 

  • A mixture of clay, silt, and sand
  • Advantages: excellent drainage and optimum water retention, contains high oxygen levels, and nutrients
  • Negative: expensive 


Sand is a type of soil that is rough with poor water retention but has good drainage. Nutrients like nitrogen will get washed away quickly when watered. Sandy soil is perfect for newbie growers because it is easy to work with. 

  • Rough structure
  • Low pH
  • Advantages: keeps soil airt, high oxygen levels, good drainage, easy to work with
  • Negative: needs frequent watering, and poor water retention


Clay is a type of soil that consists of fine mineral particles. This soil is not easy to work with and is heavy. It’s very rich in minerals and nutrients, this makes it a good choice to be included in natural grows. Clay soil can keep the water well but has poor drainage.

  • High pH
  • Fine particles
  • Advantages: keeps water, rich in nutrients
  • Negative: heavy, compact, poor drainage, and hard to work with


Silt is a type of soil that is a little bit rough that is rich in natural particles and minerals. This also has good water retention, but it has sufficient drainage. Silt soils are quite easy to work with. The natural substances and minerals within make it one of the riches soil types. 

  • Little bit rough
  • Advantages: good water retention, contains nutrients and minerals
  • Negative: fair drainage

Improve Soil Quality Amendments

If you are growing with organic soil, the probability is, it will not be perfect for growing marijuana; at least, not from the beginning. For example, the texture might not be optimum or it might have poor drainage. But you could improve any kind of soil by adding extra amendments, most of it could be found in the local grow shops. 

Coco Coir

Coco coir is made from coconut husks. These are light fibers that offer excellent water retention and could lighten compact soil. Some growers use pure coconut material with special nutrients to grow their marijuana plants. But to change the existing soil, it is a great idea to add anywhere around 30% coconut coir, based on the structure of the base soil you are using. 


Permite is the most used sole modification. Perlite comprises very light, bright-white rocks that help increase the airiness and drainage of the soil. Perlite has also a good water retention. To modify your soil with it, add an extra 10 to 15% of perlite. You could add more, but once your soil might become too light and nutrients might leak. A growing medium soil for marijuana comes with the added perlite. 


Just like Perlite, Vermiculite is a heat-tuned mineral you could use to make your soil lighter. It is also good for retaining water. Even though Vermiculite has the same traits as Perlite, the two do not have the same uses. You can use Perlite to improve airiness and drainage, while Vermiculite is to improve water retention. Fortunately, you could use both, as Vermiculite and Perlite work well together. 10% of vermiculite is enough. 

Worm Castings

Worm casting is usually seen more as an organic soil modifier because they have a plethora of useful microbes that are beneficial in growing plants. Worm castings would improve the drainage, water retention, and drainage of your soil. Use around 25 to 30% of worm casting when modifying your soil.


If your DIY marijuana soil is rich in natural material, you may not need to add nutrients to it. In the matter of fact, some cannabis growers make the error of adding vegetable scraps and manure to their soil to “fertilize” it. This outcome in the soil becomes “too hot” for the plants, which in turn affects their growth.

 If you think you need to modify your marijuana soil with nutrients, you could still easily buy bottled solutions tailored to the growth stage of the plant.

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