There are so many growing media for hydroponics systems that it can be a little overwhelming when starting out. There are traditional media such as Hydroton and Rockwool and new kinds of media like growstones and smart gravel. Choosing the right one for your needs can make a huge difference in your level of success.
Experimenting with different media is key to finding the optimal one, and each system and plant will have differing needs. To assess some of the differences between different hydroponic growing media, we’ve compiled a list of some of the most common and useful media available and compared their properties.
But to begin with, let’s take a moment to go over what a hydroponic growing medium is and what it does.
Hydroponic Growing Media
Growing media come in all shapes and sizes, with differences in drainage, air retention, weight, pH, and many other factors, all of which can affect your system and the plants you’re trying to grow.
In essence, a hydroponic growing medium is a replacement for soil in a soil-less system. It serves to create healthy root systems and support the body of the plant and gives it something to bind to. It also provides a surface for nutrient exchange and a certain level of moisture and air retention where necessary to create healthy roots and nourish the plants.
Most media support the binding of root masses, and others simply support the stem of the plant itself, but all hydroponics systems require some form of growing medium.
Growing media can have a lot of variability in their properties, making different media useful for different applications. With a multitude of hydroponics systems available, this means it’s important to pick a medium that works in the system you’re using.
Traditionally, economics and performance were the main driving forces to making the decision on a growing medium. However, sustainability and environmental impact now play a key role in the decision-making process.
Best Hydroponic Growing Medium
The best hydroponic growing medium isn’t something you can categorize. Mediums have different properties, and plants and hydro systems have different requirements. Therefore, the ‘best’ will depend on your particular needs.
Deciding on a growth medium cannot precede the decision on a hydroponics system. This is something that will need to be established before you can know which medium is best.
Once you’ve got an idea of your budget, how much drainage, how much maintenance, and other factors you’ll be working within your hydroponics system, you can judge for yourself which medium is the best fit based on your desired properties.
You’ll likely experiment with various growing media over time to find one that’s right for you, but here’s a summary of eight popular hydroponic growing media on the market.
Coco Coir
This natural fiber from coconut husks is very popular as a growing medium. It’s eco-friendly and relatively cheap and can be bought in pet and hydroponics stores. It comes loose, or as compressed bricks that can be expanded by adding them to water.
- Environmentally friendly
- Cheap
- Antifungal properties
- Great moisture retention
- Great drainage
- Good water to air ratio
Perlite
This is a porous white pebble that is inert and pH-neutral. Perlite produces a lot of dust, though, and tends to float, so it can wash away in some systems.
- Good insulator against temperature fluctuations
- Holds air very well
- Good drainage
- Dust can clog your systems
- Can dry out
Expanded Clay
This is one of the oldest and most well-known hydroponic growing mediums out there. They’re porous pebbles that are made by superheating small pieces of clay. They’re heavier than some newer alternatives and require a lot of maintenance, though.
- Good drainage
- Good root support
- Absorbs nutrients well
- Drys out quickly
- Very dusty and requires pre-cleaning
Smart Gravel
Smart Gravel is an inert, dust-free pebble designed to be the most convenient medium on the market. It’s an eco-friendly medium, made entirely from food-grade, non-recyclable plastics that are rescued from the environment. It’s pH neutral, BPA free, lightweight and ready to use right out of the bag.
• Dust-free to keep systems clean
• pH neutral
• Eco-friendly
• Lightweight
• Non-porous, offering the best drainage
• Reusable
• Resistant to algae and pests
• A little more expensive than clay pebbles
Vermiculite
This naturally-occurring mineral is often used to improve aeration and water retention in soil. It can be mixed with other growing media. It’s lightweight and can be easily found in garden centers.
- Sterile
- Good moisture retention
- Neutral pH
- Holds onto nutrients well
- Reusable does not decompose
- Can hold onto too much water
Growstones
These are specially made from recycled glass. They’re an eco-friendly alternative that is growing in popularity.
- Rougher surface allows better root binding
- Irregular-shaped pieces allow a lot of air retention and good drainage
- Porous for nutrient and water retention
- High maintenance, needs to be cleaned before use to remove residues
- High pH, is not good for beginners or aquaponics
Rice Hulls
This is a cheap and eco-friendly medium that’s available in large quantities as a by-product of rice manufacturing. It’s increasing in popularity but is often mixed with other growing media to make it more suitable.
- Cheaper than perlite
- Good drainage
- Environmentally friendly
- Does not decompose quickly
- Need to be sterilized
- Almost no water retention
Pool Noodles
These pool accessories are a surprisingly effective, cheap way to grow plants in hydroponics systems. Cross-sections of pool noodles can support the stem of a plant, allowing the roots to dangle freely into the water.
- Cheapest hydroponics medium
- Easy to use
- Easy to find
- Reusable
- Does not support the roots
- No water retention, only good for some systems
Summary
Your choice of hydroponic growing medium will depend on your system and what you want to grow in it. There are countless options to experiment with, and those are multiplied by the combinations you can make of more than one medium.
We’ve listed a few and highlighted their strengths and weaknesses. Still, ultimately it will be up to you to experiment and find the right medium or combination of media for your growing system. If you’re going for eco-friendly, pick a medium that’s either recycled or an industry by-product. If you’re simply looking for the cheapest, pool noodles win out in that category. Just make sure the medium is suitable for the system you’re using.
Hydroponics is a satisfying and variable way of gardening, and the multiple options for growing media create an exciting diversity that’s fun to explore. With tried and tested options like clay pellets now being tested against modern and more eco-friendly alternatives like Smart Gravel and Growstones, there’s never been a better time to get into hydroponics.
