Soil is the most common growing medium for houseplants, but it is far from the only option. The right medium can make watering easier, reduce pests and help roots get more oxygen. Here is how the main options compare.
Why do plants grow in soil?
Soil gives plants physical support, contains nutrients, keeps conditions such as temperature and moisture consistent, and supplies oxygen to the roots. When you grow without soil, your medium and nutrients need to cover all of these jobs. Concentrated hydroponic nutrients provide a complete profile of macro and micronutrients. Regular soil fertilisers often contain only the macronutrients nitrogen, phosphorus and potassium, which is not enough to feed a plant on its own, especially a seedling.
It naturally contains nutrients such as nitrogen, phosphorus and potassium that you would otherwise have to add.
It holds moisture and keeps roots from drying out.
It is affordable, easy to find and easy to use.
Cons:
It is messy, and its nutrients run out over time.
Overwatering and underwatering are the biggest killers of houseplants, and soil makes it hard to see what is going on.
It is where pests such as fungus gnats usually breed. Insect sticky traps help catch them.
Expanded clay balls (LECA)
A plant sits in a pot of clay balls with holes in the base, inside a second pot holding a little water. Read more in what is expanded clay.
Pros: it oxygenates the roots and helps prevent root rot, the watering system makes it hard to overwater or underwater, and without soil, pests have nowhere to breed.
Cons: it contains no nutrients, so you need to add hydroponic nutrients to the water.
Vermiculite, perlite and rockwool
Vermiculite holds water and air well and works in a similar way to clay balls. Perlite is a light, airy medium that improves drainage and is often mixed with other media. Rockwool is a clean, sterile medium widely used for germinating seeds and growing hydroponically. Shop rockwool and replant supplies.
Choosing a medium
Think about the plant you are growing and what it needs. Microgreens need a medium that drains well, gives root stability and is easy to handle, such as coconut mats. Thyme prefers drier roots, so a less absorbent medium such as perlite may suit it.
Or skip the medium and grow in water
You can grow plants in water with dissolved nutrients and no medium at all. Start with why grow with hydroponics.
