Growing cannabis plants in soil and soilless mediums

Grow medium options for cannabis growers

A question we get asked a lot at Paradise Seeds by new growers is ‘what is the best grow medium to use for cannabis plants?’ Good question! This month we are going to take a closer look at your options.

When you’re starting out you will hear a lot of advice and, yes, sometimes it can get confusing. However, after a couple of grows you will have a better idea of what works for you. Your growing medium is obviously important and you have three options – hydroponics, soil and soilless.

We recommend that beginners avoid growing with hydroponics. Yes they can give you big yields, but unless you know what you’re doing they can also give you a big headache! So in this blog piece we are going to look at soil and soilless grow mediums for marijuana.

Soil Medium for Cannabis Plants

Good soil is the gardener’s best friend and provides the easiest management for a marijuana grow novice. However, that doesn’t mean you should grab a shovel and go and dig out your garden to fill your pots! Your soil needs to have the correct pH balance (according to grow expert Jorge Cervantes, cannabis grows best in soil with a pH of 6.5 to 7.5) and also the right consistency to promote good growth.

You can make your own soil mix by adding worm castings, perlite, compost or manure to your soil to provide it with nutrition and drainage (although again watch the pH so go easy on the manure!). If this sounds too difficult to judge, or just too much hassle, there are plenty of ready mix soils that you can buy from internet suppliers or a garden center.

Top Tip: We recommend growing your cannabis seed in the pot it will spend its life in to minimize the shock of transplanting (although remember to sow the seed in a pocket of specialist seedling soil!).

Soilless Medium for Cannabis Plants

Just because soil has traditionally been the cannabis grow medium of choice, do not dismiss new innovations! In recent years more growers have started to use soilless mediums in their pots, as these methods provide the advantage of more control and speedier growth for marijuana plants.

The advantages of these mediums are that they essentially neutral, providing a foundation for you to better manage your grow. They have enhanced aeration and drainage qualities and are also unattractive homes for pests that thrive in soil. However, you need to treat these mediums differently to soil and give them more careful water/pH/nutrient management.

Coco + Perlite

Coco and Perlite are frequently used in combination in a soilless grow mix:

Coco (Coir): Particularly popular coco (or coco coir) is the brown hairy husk of the coconut chopped up into small pieces. This medium was first used in hydroponic set ups, but it has become increasingly popular as a soil substitute for cannabis plant pots. Particularly effective if using LED lights, it has anti-rot qualities and doesn’t retain water (so therefore controlled nutrient feeds are more efficient).

Perlite and Vermiculite are mineral based soilless grow mediums – Perlite is the product of volcanic cooling and Vermiculite is a hydrous phyllosilicate mineral. What these two substances do is provide air spaces for oxygen and water to move freely, thereby stimulating root growth.

Clay Pellets are pieces of clay heated to high temperature so that they develop micro and macro pores which provide aeration for roots to grow quickly, while efficiently holding moisture to allow water and nutrient retention.

Useful tip: We advise (unless stated otherwise on the packaging) to soak and wash these mediums to remove dust (be careful with Perlite dust especially – do not breathe it in) and salt residue (coco).

Soil or soilless? Each medium has its advantages and disadvantages. Of course you have the world’s knowledge at your fingertips, so take some time to do some research and we also recommend visiting grow forums to view the experience of other growers.
Good luck!