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Truth About Grow Media From Soil To Soilless, Coco, Clay, Growstones, Rockwool, Perlite, Amendments & More

We’ll look at soil, soilless, coco, clay pebbles and growstones, rockwool, and perlite as well as other amendments you can add to improve your grow media.

Truth About Grow Media From Soil To Soilless, Coco, Clay, Growstones, Rockwool, Perlite, Amendments & More

There is a wide selection of grow media to choose from. Knowing which one works best for your garden is important for a successful grow. We’ll look at soil, soilless, coco (coir), clay pebbles, growstones, rockwool, and perlite as well as other amendments you can add to improve your grow media.


Soil & Soilless

Soil and Soilless Grow Media

Soil is pretty easy to understand. It’s a natural grow media with most of the natural elements you need to grow healthy plants like peat, sand, vermiculite, some may also contain perlite or mycorrhizae for root enhancement. It contains nutrition that plants can get started on unlike inert media such as coco. It is often heavier than other media. Soilless grow media can be a little confusing. Really it’s very similar to soil but allows for more reuses without having to add as many nutrients. It tends to compact slightly less and is comprised of peat or peat substitutes such as coconut husks, barks, and pumice type materials. 

Best for: Beginners Soil and soilless grow media acts as a buffer that helps to shield plants from over or under applying nutrients to your plants. Soil and soilless media will also retain moisture longer allowing you to water less frequently and for more forgiving water adjustment.



Coco Husk & Coco Mix

Coconut husks are quickly becoming one of the most popular media to grow in. They retain moisture well, allow roots to breathe and provide a good support structure. There are many names for coco such as coir, coconut fiber, coco peat, and coco husks. They are all very similar but only vary slightly in the size of the individual media and the exact location on the coconut that they are taken from. Higher quality coco husk is treated to remove salts and is pH balanced.

Best for: Intermediate to advanced Coco offers great aeration and moisture retention but does require you to make sure it is pH neutral.


clay pebbles and growstone

Clay Pebbles & Growstones

These are great for hydroponic systems since they support good plant support while allowing excellent root access to nutrients, water, and air. Clay pebbles, sometimes called lightweight expanded clay aggregate (LECA), are a traditional media for hydroponic setups. They offer good drainage and are pH neutral. Many growstones are pH neutral or will become pH neutral once soaked in a pH balanced solution prior to use. They are made from recycled glass and are extremely porous. They can be reused if properly cleaned and sterilized between growing cycles. One of the benefits of their porous nature is that it forces roots to shoot off in more directions creating a denser root mass.

Best for: Advanced Clay and growstones require constant watering. These are best suited to a grow system that will provide constant liquid nutrients directly to the roots of plants while still allowing them access to oxygen.




Rockwool has many hydroponic friendly qualities such as being able to retain moisture well while providing good root aeration. Rockwool is similar to root pellets and plugs which are often used in propagation. It breaks apart easily so it can be sized for whatever your needs are. It maintains well throughout the growing cycle which is important especially in hydroponic systems where grow media might clog or damage water pumps and equipment. It can also be used from germination to harvest making it an all around excellent grow media.

Best for: Intermediate Rockwool requires a continual application of water and nutrients to plant roots. This is best suited to a grow system. Rockwool retains moisture well but should only be moist not damp (think a rung out sponge).




Perlite is lightweight and porous, and can be used on its own or in combination with other grow media. Perlite is a non-renewable resource but can easily be reused giving it a long life cycle. It offers good water retention, aeration and drainage. Perlite has a natural pH of 7 making it a neutral growth medium. The porous nature of perlite makes it a good temperature insulator for roots.

Best for: Beginner - Advanced When used with other soil or soilless media, its a great amendment for beginners. When used alone it should be in a grow system that will continually water roots and provide nutrients in solution.





Amendments can add nutrition, stability, or drainage benefits depending on what you choose. You can augment your grow media by adding nutrients or additives to emphasize specific traits of characteristics of your plant that make it appealing to you. For the organic grower, look for the OMRI Certified label on products to ensure that you are organically growing from germination to harvest. Common amendments include:

Bone Meal: Great for a slow release of phosphorus and protein.

Blood Meal: Excellent source of nitrogen and is often used as a composting activator.

Kelp: Promotes cell division and growth in plants.

Bat Guano: Contains high levels of nitrogen, phosphate, and potassium.

Seabird Guano: Contains higher levels of nitrogen, phosphate, and potassium than bat guano.

Perlite: Contains high levels of silicon dioxide and aids in aeration and filtration. Acts as an alternative to diatomaceous earth to deter insects and pests.

Mycorrhizae: Forms a symbiotic relationship with plant roots to promote growth and sugar/water/mineral exchange.

Worm Castings: Improves aeration of soil and enriches with micro-organisms. Attracts deep burrowing earthworms already in the soil and improves water retention.

Humic Acid / Hummus: Increases update of nutrients and can filter some toxins


Best for: Beginner - Advanced Amendments are a great way to specifically target characteristics of your gardening that make it your own. Beginners can get experience with different additives and how it effects their plants, advanced growers can emphasize specific traits of their plants that they wish to highlight.




Bulk Grow Media

Bulk Grow Media

If you have a need for bulk grow media, Hydrobuilder has a great supply that can meet any of your needs no matter how large. Buying in bulk is a great way to take advantage of volume discounts and unique shipping offers. Call us at 888-815-9763 for a custom quote on any large or bulk purchase. Bulk media often comes in pallets and can be black wrapped for security and discretion.

Best for: Intermediate - Advanced We recommend that you call us for a custom quote anytime you are considering buying bulk so we can save you money.



Questions? Call us at 888-815-9763 or email [email protected].