Pumice

Pumice is a lightweight volcanic stone used in potting mixes to improve drainage, aeration and root health. Its porous structure helps hold some moisture while still creating air space around plant roots, making it useful for succulents, cacti, bonsai and other plants that need a free-draining mix.

Use horticultural pumice when you want to open up a heavy potting mix, reduce waterlogging, or add long-lasting mineral structure. It can be blended with soil, bark, akadama, zeolite or other amendments depending on the plant and watering conditions.

Common uses for pumice in gardening:

  • Succulent and cactus mixes that need sharp drainage
  • Bonsai soil blends that need stable structure and aeration
  • Indoor and potted plants where heavy mixes stay wet too long
  • Custom potting mixes where you want mineral drainage without organic breakdown

As a general guide, start with 10–30% pumice in a potting mix, then adjust for the plant, pot size, climate and how quickly the mix dries. Plants that prefer very free-draining media may use a higher mineral component, while moisture-loving plants usually need less.

Not sure which mineral amendment suits your mix? Pumice is a good choice when drainage, aeration and lightweight structure are the priority. Other amendments may suit different jobs, so choose based on the plant and the growing conditions rather than assuming one product is best for every use.