Hydroponic gardening has many different options available to you, including the type of growing medium you use. Unlike outdoor soil gardens where water can be wasted and plants can be overwatered, the different types of growing mediums for hydroponic gardens are designed to absorb water in the most efficient ways to keep your plants healthy. Since there are so many to choose from, it can be hard to decide which is the best for you. This guide can help you choose the right growing medium for your plants if you’re struggling.
The shredded husks of ripened coconuts create one of the most popular forms of growing mediums for hydroponic gardens: coco coir. This peat-like material retains water easily, much like soil does, so you must be careful not to drown your plants when using coco coir. Coco coir peat may look like soil, but don’t be fooled! Coco coir has no nutritional value for your plants. You will still need to provide them the nutrients they need through fertilizer, just as you do with other growing mediums. Coco coir can also look like mulch if you buy it in chip form, which provides larger air pockets and less water retainment, making it a stellar material for hydroponics.
Coco coir is entirely plant-based, meaning it’s eco-friendly to use just as though you were using compost in a soil garden. Also because of the lack of nutrients, bugs don’t care about it, which makes your plants safer from pests. Because of its high water retention, it’s recommended that you use it with wick hydroponic systems.
They may look like average rocks, but these baked, porous clay balls are even better for your plants than they let on. Clay pellets retain water and nutrients but will release the water more regularly than coco coir peat. This can be good and bad, as—while your plants won’t drown—they will need to be watered more often. These pellets work best in smaller hydroponic gardens with a steady supply of water. Clay pellets can get to be expensive, so it’s inadvisable to fill a large garden with them. You’ll also need to rinse them off before you use them to avoid clay dust clogging your water supply. They should also be rinsed and sterilized regularly.
Rockwool is a unique growing medium that is sold in slabs or cubes and is made up of strands of melted basaltic rock. The result is an airy growing medium that retains water well (but not too well) and gives roots room to grow. Rockwool holds oxygen better than most growing mediums, allowing for healthier plants. Despite their manufactured nature, Rockwool growing cubes are still considered to be natural products for the sake of organic gardening. If you ever soak Rockwool, never squeeze it, as you will break down the texture that allows it to hold water.
Though Rockwool is one of the best growing mediums for your hydroponic garden, you must wear protective gear while handling it. Wear gloves, a face mask, and eye protection when handling it, as it gets dusty, and you don’t want to breathe in its particles.
Looking like tiny, white pebbles of chalky minerals is perlite, another rocky growing medium. You might recognize perlite as being in certain soil mixtures. Perlite is superheated to the point that it expands similarly to popcorn, which makes it porous like the other growing mediums. Because it was superheated, perlite is sterile and won’t transmit disease unless your plants get diseased through the gardening process. However, unlike the different types of growing mediums mentioned earlier, perlite is a limited resource. This means that eventually there could be a shortage, though as of now the world doesn’t use it fast enough. Perlite’s irregularly shaped pebbles can also prevent roots from getting water and nutrients, either by physically blocking the roots or through getting stuck in your hydroponic system.
Like Rockwool, you should be careful when handling perlite, as it can get dusty, and the dust is not healthy to be inhaled. If your system has fish in it, do not use perlite. If the dust is unhealthy for you to inhale, it’s just as unhealthy if not unhealthier for a fish to take it in as well.
A growing medium often seen in combination with perlite is vermiculite, another baked, rocklike mineral. Vermiculite retains water extremely well. It does, however, degrade rather quickly and will need to be replaced faster than other options before it clogs your system.
Another type of hydroponic growing medium is simply wood fiber. Wood fiber is good for beginners as it is easily accessible and cheap. However, it’s biodegradable and might not be sterile when you use it. Untreated wood is susceptible to rot and needs to be watched carefully when in constant proximity to water. Treated wood might have dangerous chemicals for your plants and for you or anyone that consumes fruit from the plants.
Rocks, Gravel, and Sand
There are plenty of growing mediums for your plants, and when you’re on a budget, aquarium gravel might be your go-to choice. It’s cheap and easily accessible and appropriate for fish, meaning it is likely already sterile. Brick shavings are similar to gravel but may not have the proper pH level for your plants. Brick also tends to clog up hydroponic systems and will require regular cleaning. Neither gravel nor brick shards may work with every system because of its drainage characteristics, so make sure you check before you use it.
Pumice rocks are another popular choice for hydroponic gardens. Pumice retains oxygen very well and is very lightweight. Pumice is also relatively easy to find. Just make sure not to get pumice stones that are too small, or they might get washed away.
Another very common, easy-to-find growing medium is sand. Sand won’t hold water or nutrients very well, meaning as soon as you have a nutrient deficiency, you will know. While it is the easiest to find, it’s very heavy and could easily block your hydroponic system.
At FloraFlex, we stock both coco coir and Rockwool for your gardening needs. As with any of the growing mediums required for hydroponic gardens, remember to supply your plants with the nutrients they would normally get from the soil. These nutrients can be supplied by organic fertilizer that you add to the water.