Sure, the “hydro” in hydroponics refers to water, but do you want to know a secret?
Straight water isn’t the only way to grow in hydroponics. Another and, many would say, easier way is to grow the plants in sterile, soil-less substances called “growing media.”
When growing in water alone, it can be difficult to create the stable growing conditions your plants desire, since it’s harder to control the pH of the nutrient solution (something that’s very important when it comes to keeping plants healthy). You also need a more complicated hydroponics system setup complete with aeration pumps when you only grow in water.
On the other hand, growing media provide a sterile way to ensure the roots are getting the air they need, provide more consistent pH levels, and support plants so they won’t flop over. The “sterile” aspect is important because, that way, you’re less likely to introduce bacterial or fungal problems into the watering system and that system will be less likely to clog. Most growing media also have a neutral pH, so they won’t make the nutrient solution you’re using more acidic or alkaline than it’s supposed to be something that can affect the way nutrients are absorbed by the plants.
Of course, not all growing media are the same. Here’s a quick guide to 3 popular types, all available from Mother Earth®:
Mother Earth® Hydroton® is made from clay that is rolled into balls and fired at high temperature. The result is a pH-neutral, semi-porous material with good “capillary action” in other words, it absorbs water that can then move around easily, allowing for good nutrient solution circulation around the plants’ roots. The clay balls are also dense enough that they won’t float around in growing containers. You can even reuse Hydroton® if you thoroughly clean it between plantings. This growing medium works especially well for systems with sub-irrigation (watering from the bottom, as with wick systems) or constant drip irrigation.
Used either alone or in a mix with other materials, Mother Earth® Perlite is a naturally occurring silica rock that expands up to 20 times its original volume when heated kind of like popcorn that’s being popped. What results is a material that is both sterile and lightweight, has a neutral pH, and is extremely effective at creating pockets of needed oxygen in the plants’ root zones. Perlite is sometimes mixed with coco coir to create a mixture (such as Mother Earth® Coco + Perlite) that retains water and provides excellent aeration. By itself, perlite is a good growing media choice for sub-irrigation systems (such the simple wick system). When mixed with coco coir, it can be used with sub-irrigation systems, drip systems, and flood-and-drain systems. Never use perlite in aquaponics systems, though.
Coco coir, such as Mother Earth® Coco, is a lightweight, pH-neutral growing media made from the husks of coconut palms and unlike peat moss, it’s a renewable resource. This type of growing medium works well in hand-watered and timed-drip systems. If you need a lot of coco coir, you can buy it in bulk (in compressed form), as with the Mother Earth® Coco Bale. To use, just soak the bale and break it up with your hands.
Mother Earth® Charged Coco® has all of the same great attributes of Mother Earth® Coco, but is pre-loaded with beneficial nutrients to jump-start plant growth and reduce the chance of transplant shock. As noted above, coco coir is also often mixed with perlite to create a soilless mix with exceptional water-holding capacity and aeration. One important note: You should always use a coco-specific nutrient solution when growing with coco coir.
As a rule of thumb, if you want to mix growing media, choose types with smaller particles rather than larger ones. You wouldn’t want to mix hydroton with small perlite or coco coir, for example, but (as you already know) coco coir and perlite mix well together.
So now that you know the best kept secret of hydroponics, the next step is to choose the right growing medium to your system. Use the guide above and you’ll be well on your way to success!