perlite cannabis

Perlite And Cannabis Cultivation

Perlite is heat-treated volcanic glass. It is used by cannabis growers to improve the quality of the grow medium as it guarantees proper drainage and aeration. Read on to see how perlite can improve your next grow.


Perlite is often added to grow mediums when cultivating cannabis. It is an excellent addition to coco coir and improves the structure of organic soils. Perlite is neutral and will not alter nutrient EC or water pH. Many nurseries add perlite to soil to decrease overall weight, which makes handling potted plants easier. This is also an advantage for the cannabis grower who moves their plants to take advantage of lighting conditions.


Perlite is a soil conditioner and growing medium that isn’t made from pearls, but is very light. It occurs naturally as an amorphous volcanic glass with a relatively high water content. When this natural substance is heated to extremely high temperatures (850-900°C), it expands substantially to become the commercial product perlite. Commercial perlite is extremely white due to the reflectivity of the bubbles in its structure, which also make it very lightweight.

Perlite is available in three grades; fine, medium, and coarse, with the fine grade usually selected when growing cannabis. It is used as a soil or coco coir amendment that promotes proper drainage and air retention. Perlite is the perfect complement to coco coir, which can retain a lot of water. Perlite holds a film of air close to its surface and creates air pockets no matter how wet the growing medium is.

Perlite is a common soil amendment that helps stimulate marijuana growth. The increase in drainage helps prevent overwatering and nutrient buildup, while increasing root penetration and oxygen availability.

Perlite is suited perfectly for clones. New roots can penetrate the lightweight structure of perlite with little effort. Faster root growth means a quicker turnaround from cutting to growing plant. Perlite drains so well there is little chance of drowning your cuttings.


Many commercially available growing mediums will already have perlite added. If not, you can add your own. It is common to add between 10-50% by volume of perlite.

Add up to 20% if you only intend to use small amounts of nutrients and additives. The perlite will help with water and nutrient retention.

Add up to 50% if you intend to use a lot of nutrients and supplements to help prevent nutrient buildup. Too many nutrients can cause lockout in the root zone. The perlite will ensure efficient drainage.

Perlite is available in smaller bags from any nursery or hardware store. If you intend to use a lot, contact the manufacturer and arrange for bulk buying. Bags are usually 100 litres and make you seem like a superhero when you handle them as they are so light.

Perlite is a common addition to grow mediums when cultivating cannabis. Find out why this lightweight soil conditioner is so effective.

Should You Add Perlite to Your Soil?

A common soil amendment for cannabis plant is a substance called perlite. This can be added to soil or coco coir to improve its air-holding capabilities and increase overall drainage ability. It’s not a requirement for cannabis growth, but it’s so useful that nearly all recommended potting mixes contain at least a little perlite.

Horticultural Perlite – A great amendment for soil or coco when growing cannabis. Perlite looks like little white rocks, but the pieces feel oddly light and airy, almost like popcorn.

Nearly All High-Quality Cannabis Soil Mixes Contain At Least a Little Perlite

A 50/50 Potting Mix of Coco & Perlite – Perlite provides more oxygen to the roots, resulting in faster growth. It also prevents nutrient buildup. This perfectly complements the ability of coco coir to hold onto a ton of water. Learn how to mix up your own coco/perlite mix!

Perlite for Growing Marijuana

Perlite is one of the most common soil amendments. It is highly recommended for any cannabis soil or coco mix that doesn’t contain some already.

Perlite appears as very light, airy white “rocks” that feel almost like popcorn.

Adding perlite increases the overall drainage ability in a potting mix, helping prevent overwatering.

Perlite helps prevent nutrient buildup which makes it a good choice when growers are giving nutrients and supplements in the water

More oxygen in your soil or coco results in faster growth. Roots love oxygen! Perlite increases the amount of oxygen available to the plant roots because it does not retain water. As a result, air pockets form around the perlite even when the growing medium is wet.

How Much Perlite to Add?

It’s recommended to add perlite so it makes up around 10-50% of the total volume of potting mix.

Add 10-20% perlite if you want better water retention and don’t plan on using a lot of extra nutrients. This is because a lot of extra perlite can cause the nutrients leach out faster from the soil as water drains through easily.

Add 30-50% perlite if you plan to use a lot of added nutrients or supplements and are looking to get the fastest growth from your plants.

I have used many types of perlite including Epsoma, Black Gold, Shultz and even Miracle-Gro perlite. Any 8-quart bag of perlite will work. Perlite can often be found in garden stores or the garden section of home improvement stores like Home Depot and Lowes. I normally advise against all things Miracle-Gro, but their 8-quart bag of perlite is okay if you can’t find anything else.

What is Perlite?

The light, almost fluffy perlite we use for gardening does not occur naturally. It is actually manufactured from expanded volcanic rock.

It all starts with lava (like the kind from a volcano!) which cools and sometimes turns into obsidian, a shiny black glass that can be mined from the ground.

Example of obsidian, which is formed out of lava

As centuries pass, obsidian absorbs water from the air. This hydrated obsidian is mined and crushed into small pieces. The pieces are then expanded by adding huge amounts of heat. Due to the high amount of water contained inside, the heat causes the perlite pieces to pop like popcorn. That is why perlite feels so light – it is made up mostly of air!

Production of Horticultural Perlite

Should You Add Perlite to Your Soil? A common soil amendment for cannabis plant is a substance called perlite . This can be added to soil or coco coir to improve its air-holding capabilities and