Cannabis plants have an amazing capacity to adapt to different growing mediums, which gives growers significant advantages, as they can be grown in diverse places using different types of substrates. Let's examine the different options for the medium your plants are grown in.
What is the substrate?
A substrate is a surface on which an organism is attached to or grows on. Soil is the typical substrate for growing plants, but as growers gain insights into increasing yields, substrates have evolved over time along with how we grow.
Mother Nature's Soil
Soil is the typical substrate type for most non-marine plants grown on earth and used for centuries due to its natural convenience and wide-spread availability.
And while soil is the prevailing substrate, especially in outdoor grows, the cannabis plant is highly adaptive and shows an ability to grow in many types of substrates. Indoor grow operations are becoming an industry standard that provides an opportunity to experiment with different growing mediums to find the best solution for your grow operation.
Obtained from coconut husk, coco peat is a 100% organic product that is quickly decomposable. Coconut substrate naturally contains Trichoderma, which prevents the spread of root fungus and encourages healthy plant growth. It's also appropriate for four growing cycles in succession, so there's no need to change substrates during the growth cycle.
Generally, plants grow healthier and faster in coco than in other mediums. Another advantage with coco is that it has superior drainage while also being ultra-absorbent – meaning your plants won't go thirsty – it does require more watering than with soil.
A lightweight hydroponic substrate, rockwool, is made from forming molten basaltic rock into fine fibers. Once it's transformed into fibers, it's further manipulated and formed into blocks, cubes, growing slabs, and granular products.
Popular for germinating seeds because of their superior moisture retention, rockwool is excellent at keeping seeds or seedlings from drying out, but it doesn't allow them to sit in a saturated environment. Moisture is a determining factor in seed germination, and rockwool provides an excellent substrate for cannabis seeds. Many growers use rockwool for germinating seeds before planting them in soil or other substrates.
Often referred to as hydroton, clay pebbles are a hydroponic substrate made up of small marble or peanut size balls made of clay. Useful in both hydroponic and aquaponic systems, hydrotons are excellent water absorbers, collecting excess water it stores for later use. It prevents roots from being damaged due to excess water, which can cause fungus. Typically clay pebbles are used as a base, supplementing other substrates and can also be used as a standalone material. One of the benefits of clay pebbles is that they allow for thorough aeration, further preventing root rot.
Perlite is a baked volcanic rock that provides an airy substrate with enhanced drainage capacity. Perlite is often mixed with soil to improve its structure as it's smaller than clay pebbles and improves soil aeration. It has a consistent quality, is germ-free, and presents an ideal water/air ratio for plants to thrive.
After the baking and expanding process, horticultural perlite is separated into four categories based on the size of the particle: super coarse, coarse, medium, and fine grade. Super coarse perlite has a water holding capacity of 19%. And while its ability to hold water is impressive, the downside is that it requires an additional substrate (like soil) to be effective. Its small size and buoyancy cause it to float, and therefore it doesn't anchor plants well on its own.
Your decision on which substrate to use for your cannabis grow is mainly dependent on your goals. Indoor or outside? Hydroponics or standard irrigation? Once you decide how you want to grow, the decision on which substrate or combination of substrate materials will be easy.