Which Soilless Media Is Ideal for Growing Cannabis?

Which soilless media is right for growing your cannabis? Learn the pros and cons of perlite, vermiculite, and coco coir.
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One of the first decisions you’ll make when you’re preparing to grow cannabis is which media you’ll use. Oftentimes, growers find soilless mixes—a combination of organic and inorganic materials without soil—are the best choice for growing cannabis. Because you can craft your soilless media however you want by combining different organic and inorganic materials, you can decide the right profile for your plants, helping them grow the way you want (bigger and better!). A soilless mix is just that: a mix of substrates that work best for your growing situation. Common choices include perlite, vermiculite, and coco coir. Which one is right for you? Read on to find out.

Perlite as Your Soilless Media

Perlite is formed by molten (magmatic) rock, also known as volcanic glass. When it’s heated rapidly in industrial furnaces, the volcanic glass softens, causing the entrapped water molecules to turn to steam and expand the perlite particles—much like popcorn. Expanded perlite is renowned for cannabis growing because of its many benefits.


  • Perlite improves aeration to ensure your plants get appropriate oxygen to the root zones. This also helps prevent waterlogging and overwatering.
  • This mineral is free of organic contaminants, making it resistant to abiotic and biotic stressors.
  • Due to its light weight, it is easy to mix with other mediums and stays lightweight even after watering in case you need to move your plants around.


  • While beneficial for your cannabis, some people don’t like how quickly water drains from soilless media featuring perlite. Some say it drains so fast that it ends up on their growing stand.

When It’s Best

Perlite is a good choice for your soilless media if you want to add porosity to your soil and prevent compaction while also ensuring adequate moisture at the root zone. Many growers choose perlite because of its inorganic state.

Vermiculite as Your Soilless Media

Vermiculite is a hydrated magnesium aluminum sheet silicate mineral closely related to mica. It’s an efficient growing aid often used in the horticulture industry. When subjected to heat, vermiculite exfoliates and forms particles that are lightweight and highly absorbent. It’s a popular choice for cannabis growers as a soilless media and in  hydroponic systems.


  • Vermiculite provides your cannabis with potassium and magnesium.
  • Vermiculite improves aeration while retaining moisture to promote faster root growth.
  • Vermiculite has a high nutrient-holding capacity and acts as a magnet for nutrients like potassium, calcium, and magnesium.
  • It slowly re-releases valuable nutrients back into the soil, adding to the growing cycle.
  • Like perlite, this mineral is lightweight for easy mixing with other mediums.
  • Vermiculite is sterile and does not put your cannabis at greater risk of falling victim to abiotic and biotic stressors.


  • Vermiculite already provides some nutrients so you’ll need to be mindful when mixing your own. It does not provide a “blank slate” like perlite.
  • Because it holds so much water, it can make your pots heavy when wet.

When It’s Best

Vermiculite is a great choice when you want to ensure your cannabis is making the most of the nutrients you’re adding. It’s also beneficial when you need the root zone to have the right balance of oxygen and moisture.

Coco Coir as Your Soilless Media

Compared to other soil media mixes, using coconut coir is considered a newer method. Coir is everything in between the shell and the outer coating of the coconut seed, which at one point was considered waste. Coir is most popular with hydroponic growers. 


  • Coco coir has a high nutrient holding capacity and naturally contributes potassium to your soilless mix.
  • This media has a high water-holding capacity while also ensuring air porosity.
  • Coco coir has a low dry bulk density, so it isn’t heavy when initially mixing with other substrates.


  • Its pH is close to (but not exactly) neutral at approximately 6 to 6.7.
  • It’s grown in ocean climates and can be high in salts. Some growers recommend washing coco coir before use, adding a step to your growing process.
  • The high potassium content can interfere with calcium absorption. Adding calcium amendments to the soil mix can take care of this problem, but it’s an additional step and cost.
  • Coco coir has a high wet bulk density, making your soilless mix heavier when wet.
  • There is a higher chance of overwatering plants than soil media mixes using perlite or rockwool.

When It’s Best

Coco coir is best when mixed with other soilless mediums like perlite and vermiculite to maximize benefits.

To Grow Great, You Need a Hero. Harvest Hero.

Harvest Hero Perlite+ Silica

Similar to our Enhanced Perlite Mix, this blend spotlights silica in the form of diatomaceous earth and perlite to support all stages of cannabis growth. Without the addition of nutrients, you have control of the ones you add to influence the way your plants grow. The benefits of this blend include:

  • Natural soil substrate: an organic amendment that will increase growth.
  • Maintains high levels of oxygen in the soil.
  • Increases your crops’ uptake in water and essential nutrients.
  • Minimizes pH fluctuations by keeping oxygen levels consistent.
  • Increases plant mass and plant growth. The silica fortifies the plant tissue to improve soil conditions in times of abiotic stress, like during temperature extremes, sunlight, and water extremes.

Experience Heroic Horticulture with Harvest Hero

Help your plants get the nutrition they need to ensure robust, vigorous growth. Our soilless mediums are great for recreational growers and professional horticulturists. Shop now for FREE SHIPPING on all available product sizes of 8 quart through 3 cubic foot bags.

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