Hydrograins are essential for good drainage, whether they are used in containers for patio plants, roses or petunias. Always spread a 4–5 cm-layer of hydrograins in the bottom of the pot This ensures that excess water is drained away, so that the roots of your plants do not 'drown'.DCM Hydrograins are baked and washed granules of pure clay that are safe for the plants. They are suitable for hydroponics, as cover material or to improve drainage at the bottom of pots. An additional advantage is that it makes large pots less heavy.