A natural, coarse-grade pumice that supports healthy root systems in larger pots and more mature plants. This pumice size is ideal for growers who require increased drainage and airflow while still maintaining nutrient-holding capability.

These pumice rocks for plants have pores that naturally absorb and slowly release water and nutrients, helping create optimal growing conditions in bonsai, succulents, and cactus gardens.

Features

• Coarse particle size: 420mm
• Excellent for drainage and aeration
• Retains water and nutrients in micro-pores
• Fully washed and screened no dust or fines
• Sustainably sourced from a land-based site near Lake Taupo, NZ
• Naturally sterile, pH-neutral, and chemically inert
• Suitable for hydroponics, raised beds, pots, and dry-loving plants

Why You Should Buy

This coarser grade of pumice is especially well-suited to larger plants, including older bonsai and large succulents, which benefit from increased airflow around roots. Unlike soil additives that compact over time, this pumice maintains its structure long-term. Its superior drainage minimizes the risk of overwatering, while the porous surface helps hold just enough moisture and nutrients for gradual release, supporting stronger, more resilient plants.

Common Applications

• Bonsai cultivation with a need for heavier drainage
• Cactus and succulent soil mixes
• Soil amendment for large pots or garden beds
• Hydroponic growing as part of an inert medium
• Soil conditioning in no-till gardening

FAQs

Whats the difference between this and the 17mm grade?
The 420mm grade has larger particles, offering even greater drainage and airflow, making it ideal for larger root systems or plants in bigger containers.

Is it pre-washed?
Yes, it’s washed and screened to remove dust and fines, ensuring it wont compact or concrete in your soil mix.

Can I mix this with organic potting soil?
Absolutely. It can be mixed directly with soil to improve structure and oxygenation.

Will this break down over time?
No, pumice is a long-lasting mineral aggregate that keeps its shape and function.

Can it be used in hydroponic systems?
Yes, its inert and pH neutral, making it perfect for hydroponic applications or as a base media layer.