Best Growing Medium for Cannabis Plants

One of the most common mistakes among rookie growers is not investing in a good quality growing medium for their marijuana plants, when it’s an essential element for them to develop properly. However, before deciding on the best growing medium for cannabis plants, you should first know the characteristics of the most common options and choose the one that adapts best to the needs of your cannabis plants.

What is a growing medium for cannabis?

In general terms, a growing medium is the surface where a plant lives. Its quality varies according to the components that form it. There are as many possible combinations as vegetables on the planet. It is not uncommon for growers to make their own substrate, making sure it meets the nutritional needs of their crop. This is the reason why it is not possible to decide which growing medium is best to grow cannabis. It all depends on the requirements of the plants.

Outdoor marijuana crops are usually performed on direct soil with added specific additives, to make sure plants receive the nutrients that the ground might be lacking.

The easiest option is to buy a ready made growing medium in a trustworthy grow shop. However, it is still important to choose the one that adapts best to your crop, taking into account growing area, climate and strain.

Components of a good growing medium for cannabis plants

The common characteristics that all substrates must share are correct texture, good draining capacity, proper water retention, pH values close to 6 (anything between 5.8 and 6.3 works well for cannabis) and a good amount of nutrients to cover the needs of marijuana plants during the germination process. However, the best growing mediums have enough nutrients to feed the plant up to the flowering phase, or nearly. 

A good quality growing medium is made from a combination of various components in order to provide it with the described characteristics. Usually, a substrate base includes black and blonde peat with different additions.

Coco coir

Coco coir can be used on its own in marijuana hydroponic grows or to improve a soil substrate. It is inert, which means it doesn’t have any nutrients, but it’s an excellent aid to oxygenate the roots and give soil a spongy texture.

Not all coco coir types are suitable for marijuana cultivation due to its composition. To revert this situation, it needs to be rinsed with fresh water and treated with a buffering agent. This way, coco coir will remain at the suitable pH level to improve a growing medium for cannabis plants.

Perlite

Perlite is an amorphous volcanic glass that improves cannabis growing mediums by increasing water retention and oxygenation, which results in greater plant growth. An excess of this component can damage the plants by causing too much water retention. Therefore, the composition of the growing medium should never include more than 20% of perlite.

Vermiculite

Vermiculite’s function is very similar to perlite: to keep the substrate humid and properly aired. It is also a good pH stabilizer and a good thermal insulator, perfect for outdoor summer crops.

Worm humus

Humus provides the growing medium with various features. On one hand, it increases drainage and water retention, but it’s also rich in micro-nutrients, which improves soil fertility.

Rockwool

This growing medium is often used to germinate marijuana seeds or to grow cuttings for hydroponics. It is also suitable to improve water retention in any growing medium, but because it’s an inert substance, the plant will require other nutrient sources. 

Bat guano

Bat guano is a well-known fertilizer that provides all the necessary nutrients cannabis plants need. However, it also has natural fungicide properties, boosts the decomposition process and improves substrate’s texture and drainage.

Arlite or expanded clay

Expanded clay is made of volcanic rock covered with clay. When plants have been watered excessively, expanded clay lets water flow through the pebbles while airing the substrate. It is often placed on the base of the pot, although its use in hydroponic grows is also quite extended.

Mycorrhizae

Mycorrhizae play a very important role in nutrient absorption by creating a symbiotic relationship with the root system while protecting it against soil pathogens. 

Humic and fulvic acids

The combination of both elements improves cannabis growing mediums by increasing its performance and stress resistance, thus, promoting bigger plants.

How to choose the best growing medium for cannabis plants

Choosing the right growing medium for cannabis depends on the type of grow and where it takes place.

When growing outdoors, the main thing to take into account is the climate of the chosen area. In warm areas, perlite mixed with coco coir can be very useful to guarantee a good balance between water retention and substrate aeration. This way, plants always have the right amount of water.

On the contrary, cold areas require a growing medium for cannabis plants that doesn’t retain as much water; they won’t need as much hydration as if they were in warm areas. The best components to insulate roots from the cold are perlite or vermiculite.

Another thing to take into consideration is the type of grow. A 100 % organic grow needs large amounts of blonde peat to provide the growing medium with enough material to breakdown and obtain nutrients. In this case, the substrate can be improved by adding elements that speed up the decomposition process, such as mycorrhizae or warm humus.

Guerrilla grows will benefit from cannabis growing mediums with slow-releasing components capable of retaining enough humidity to withstand a few days without water. Large amounts of black peat are an excellent option.

Guerrilla and organic grows can both benefit greatly from Super Soil; although this technique does require certain knowledge in the matter.

Hydroponic cannabis grows need a growing medium made of inert medium improvers, such as expanded clay, coco coir or rockwool.

In conclusion, there is a great variety of fertilizers from which to choose. However, the best growing medium for cannabis is not the one with more ingredients; but the one that takes care of the requirements of the grow according to the type of crop, area and strain.