As its name suggests, a soilless medium is any sterile medium for growing plants that doesn’t involve soil. There are soilless media made from organic and inorganic materials. These materials are often used with fertilizers, which ensure plants receive all the nutrients they need to thrive.
The History of the Soilless Growing Medium
Growers have experimented with soilless growing media for the last century. In those early days, manure was a key component of the soil alternatives. Some plants thrived with the nutrients of manure, but others died. That’s because manure contains pathogens that can threaten plants.
Understanding this, scientists developed the idea of standardizing soilless media. They also ruled out the use of manure. Today when we talk about soilless media, we always refer to sterile products.
Types of Soilless Media
People interested in growing plants in soilless media have several options. Some people use soilless growing media on their own,Â but they are usually combined with one another for optimum results. Some of the most popular soilless growing media include:
- Sphagnum peat moss: A lightweight material with a coarse texture that holds water well and promotes aeration. Best used with other soilless media, it’s perfect for germinating seeds.
- Coconut coir: The fibrous part of the coconut husk, coconut coir retains moisture while allowing air to pass through. Coconut husks help coconut seeds sprout by protecting them from the elements. Coconut coir works in the same way, helping all new seeds germinate by keeping them safe. It works similarly to sphagnum peat moss, but it is far less messy. As it takes hundreds of years to form peat, it’s also a more sustainable choice. Since it is a natural by-product of coconuts, it is also one of the greenest soilless media on the market.
- Vermiculite: Small balls of aluminum-iron magnesium silicate that aerates other soilless growing media. It also increases nutrient and water retention.
- Perlite: Small balls of volcanic glass that can aerate other soilless growing media. It is often used interchangeably with vermiculite as a rooting medium, although it is more porous so it helps water drain better.
- Growstones: These recycled glass stones combine with calcium carbonate to help them retain air and water. However, their porous nature can make transplanting without root damage challenging.
- Coarse sand: Coarse sand aerates soilless media and improves drainage but doesn’t retain water as some other soilless media do.
- Bark: Bark works in a similar way to coarse sand, boosting drainage and airspace without retaining water. However, since bark particles are larger, they have even greater water retention properties. Bark mixes are a great choice for mature plants which could risk root rot if they get too damp.
- Rock wool: This wool-like substance is a mix of melted basalt blended with chalk and sand, then spun into fibrous threads. It’s very lightweight and retains water well. It works best with mature plants with established root systems. Rock wool is sometimes called stone wool or mineral wool.
Benefits of Soilless Media
Using a soilless growing medium gives you more control over the growing experience than soil. When you use soil, you never know what you’re working with exactly. Soilless mixes are sterile, so they never contain bacteria, disease spores, insect pests, or weed seeds like soils can.
You can also blend different soilless media to get the mix you like. The different soilless media you add impact the water retention, drainage rate, and airspace of your mix. This ensures you can create the perfect growing conditions for your plants. Read up on what they like, then create a soilless medium blend that helps them reach their potential. Alternatively, you can choose a commercial soilless medium, which takes the guesswork out of the process.
Soilless media have a lot more space for air, roots, and water than dense soils like clay soils do. You’ll notice all that space helps roots grow longer and faster in soilless mediums. They also grow more root hairs, which help them absorb the nutrients they need to grow stronger.
Since they have a lot of space for air, roots, and water, soilless media are also lighter than natural soils. That might seem like a small consideration, but it’s certainly a key factor if you like to move your pots around.
Tips for Growing Plants in Soilless Media
Soilless growing media make growing plants easy. However, some handy tips can certainly simplify the process. Keep these tips in mind when you’re growing plants in your favorite soilless growing medium.
Soilless media contain virtually no nutrients, so you’ll need to add your own. You can find many nutrient mixes from your local gardening supplies store.
Soilless media are perfect for growing seeds, but you’ll need to take extra care until they germinate. Make sure your seed is well-covered with your soilless growing medium. Seeds grow best in warm, moist, dark places. You should also keep your seeds away from natural predators. Rodents, birds, ants, and other insects can all attack seeds for their nutrients. If there are pests in your outdoor areas, consider bringing your seeds inside until they sprout.
If you’re working with seedlings or mature plants, make sure your soilless medium totally covers your plant’s roots. Roots exposed to sunlight can burn or grow algae or fungi. Make sure you cover them carefully to keep them safe.
Plant roots absorb nutrients best when they’re in an environment with the right pH level. Optimal pH levels vary from plant family to plant family. Monitor your soilless growing medium’s pH levels carefully and adjust them as you need to keep your plants happy.
Soilless media make growing plants easy so you can spend less time tending them and more time appreciating them. If you feel you’ve always felt you have a black thumb or you just want to garden smarter, a soilless medium is the ideal solution.