For pots and terrariums where water collects at the bottom and the roots sit in it. Clay balls make a drainage layer that keeps that water away from the soil, and they're also good for semi-hydro growing and for rooting cuttings. They're clean, don't rot, and can be rinsed and reused for years. 8–16mm. 3L resealable bag.
These are small balls of clay fired in a kiln until they puff up, leaving them porous and light. Each one soaks up some water and lets it go slowly, while the spaces between them stay full of air. Because they're inorganic, they never break down, smell or go sour, which is exactly what you want at the bottom of a closed glass terrarium or in a pot without drainage holes.
How to use
- As a drainage layer: put a layer a few centimetres deep in the bottom of a terrarium or a pot without holes, then add a sheet of mesh or a little moss to stop soil washing down. Our Terrarium Soil Mix goes on top.
- For semi-hydro: rinse the clay balls well, wash every bit of soil from the plant's roots, and pot it into the clay balls with a little water standing in the bottom of the pot. Feed with a fertiliser made for hydroponic or semi-hydro growing. Ordinary soil feeds aren't suited to it.
- For cuttings: root them in a jar of clay balls and water.
- As a top layer: a layer over the soil slows evaporation and keeps the surface drier.
- Rinse before use, and rinse again to reuse when you repot.
At a glance
| What it is | Expanded clay balls (hydro balls) |
| Size | 8–16mm |
| Origin | Belgium |
| pH | About 7.3 (neutral) |
| Water holding | About 31% |
| Lasts | Years; rinse and reuse |
| Volume | 3 litres, resealable bag |
- Can be harmful if eaten. Keep it out of reach of pets and children.