Many different types of grow medium can be used in hydroponics. There really is no right answer to the question of what hydroponic grow medium works the best. It varies depending on what you’re growing, the type of hydroponic system you’re using, and your personal preference. There could be several grow mediums that could fit your needs which may bring it down to price and availability. Here’s an overview of some of the main hydroponic grow mediums used.
Rockwool is a long used hydroponic grow medium, especially when it comes to starting plants or starting clones. It has to be ph balanced before being used. This is done by soaking the cubes ph balanced water. Rockwool is made to have a perfect airflow for plant roots to it’ important to not squeeze the cubes. Rockwool is a porous medium that is made up mainly of rock, which is heated, melted, spun into strands, and then formed into cubes, blocks, or slabs. You can find rock wool online or at your local hydroponics store.
Oasis cubes are a grow medium designed for both seeds and cuttings. It’s similar to rockwool, used for germination, but does not have to be pre-soaked. It is a medium that has a neutral ph and great water retention. It’s pretty versatile as it can be transplanted into many different types of hydroponic systems and grow mediums.
Expanded Clay Pebbles
Expanded clay pebbles are often referred to as hydroton, which is actually a brand name, or just clay pebbles. It provides a great support for the plant, fits well into net pots and has a neutral Ph. This is not the cheapest hydroponic grow medium to start out but can be the most cost-effective if growing is a long-term hobby or investment. After harvesting your garden, expanded clay can be cleaned and reused for your next crops grow medium. its many benefits and ease of use mean it’s available in almost every hydroponic shop. Make sure to not breathe in dust and rinse well before using.
Coco chips and fiber come from the husk of coconuts. This is an organic grow medium that is quickly picking up in popularity among hydroponic growers. It provides great moisture retention while also allowing great air flow to the roots. This hydroponic grow medium comes in 2 forms, chips and fiber. The chip form is similar to wood chips while the fiber is stringy.
You may be familiar with perlite as an additive to garden soil. This hydroponic grow medium allows oxygen to get to the roots and better water drainage. It is a type of volcanic glass that, when heated, pop similar to popcorn. Perlite can be used alone in hydroponic systems like the drip system, but it doesn’t retain water very well. It also floats, so it doesn’t work well as a standalone in some hydroponic systems. It is often mixed with other grow medium such as vermiculite; a 50/50 mix works well. Perlite is inexpensive and is also reusable. The dust from perlite is not healthy for you or your plants, so make sure to wear a mask and rinse it before use.
Vermiculite is a mined mineral rock. There are different types of vermiculite, so make sure you’re getting some that work with hydroponics. Vermiculate as a hydroponic grow medium is very good at retaining moisture, but when used alone it can be too much moisture for healthy roots. its most often used in conjunction with another grow medium like perlite. This gives the roots the moisture it needs while the perlite allows sufficient oxygen to the roots.
I’ve had a lot of success using different types of rock and gravel from the hardware store as my hydroponic grow medium. It’s easy to come by and when a lot of grow medium is needed, such as in a flood and drain system, rock is one of the more cost-effective grow mediums to choose from. I’ve found pea gravel, lava rock and river rock to work well with many of my hydroponic systems as grow medium. Another thing to keep in mind is heat. The sun will heat rock which will in turn raise the temperature of your hydroponic nutrient solution.
There are many things that could be used as hydroponic grow medium. Really anything that a plant can grow in would be considered a medium, including air (Aeroponics). Hydroponic grow mediums have to allow both oxygen and water to the roots while securing the plant into your hydroponic system. Unfortunately, there is no real answer to what hydroponic grow medium works best. It takes experimentation with different types to find what works best for you!
December 11, 2018 at 12:05 pm
Thanks for the feedback Kate! I’m glad you found the information helpful!
July 20, 2020 at 6:44 pm
I am new to hydroponics. Is it OK to substitute Coco Coir for clay pebbles?
August 1, 2020 at 11:18 am
Hey Paul! You can use coco coir instead of clay pebbles. The nutrient schedule is just a little different then most other hydroponics systems as coco coir isn’t for recirculating systems.
February 5, 2019 at 9:33 pm
Hi, i have just come across your site and found it very interesting and informative. Thank you so much. This is awesome and great, I love it.
Inia Bunsa – Local Farmer, Papua New Guinea.
February 6, 2019 at 9:01 pm
Thanks for the feedback Inia, glad you found it useful!
February 21, 2019 at 10:19 am
Can we use sponge or Foam instead of Clay Pebbles or Rockwool as a growing medium.
September 30, 2019 at 4:18 pm
Great site, thank you!
I want to grow pelletized basil seeds in Rockwool in a net pot but without the clay pallets. Can I do that?
October 2, 2019 at 8:55 pm
Thanks for the feedback Sabine! You can definitely use rockwool in net pots without the clay pellets. I would recommend getting net pots that fit tight on your rockwool to keep your plant stable. You could also use 2 inch net pots and rapid rooter plugs.
November 3, 2020 at 8:47 am
I am interested