Drainage Layer Calculator — Pot Drainage Material

Opinions are divided. Modern thinking says drainage layers can create a perched water table. The most important thing is having drainage holes. A thin layer of crocks stops compost washing out.

Keep it thin — 2-3 cm for most pots. Deeper drainage layers waste root space and can actually hold water.

Broken crocks, clean gravel, perlite, or LECA (clay pebbles). Avoid polystyrene as it can float and break up.

Lightweight Expanded Clay Aggregate. Clay balls that are lightweight and retain some moisture. Good for large pots where weight is a concern.

Yes, drainage holes are essential. Without them, water collects at the bottom and roots rot. If using decorative pots without holes, use an inner pot with drainage.