Substrate
Japanese Pumice, 3-6mm, 5L
Imported Japanese pumice, 3-6mm. Washed and sifted. 5L bag.
AU$29.95
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Imported Japanese pumice, washed and sifted to remove dust. Pumice holds air and some water, does not break down in the pot, and adds drainage to any mix. Use it as the inorganic base of a soil mix with akadama and pine bark, or straight for cuttings and trees in recovery. 3-6mm particle size. 5 litre bag.
How much do I need?
Approximate fill, measured as pot length × width × depth. Allow extra for a drainage layer in deeper pots.
What Japanese pumice is
Pumice is a light volcanic rock full of fine pores, so each particle holds air and some water at the same time. It does not break down in the pot, and it is close to neutral, so it adds drainage and structure to any mix without changing how the mix behaves chemically. This is imported Japanese pumice, washed and sifted to 3-6mm.
How it is used in a mix
Pumice is the inorganic partner to akadama or Sakadama: raising its share makes the mix drain faster and run drier. For conifers, blend it with kiryuzuna as the drier half of the mix. With pine bark as the organic part, akadama, pumice and bark make a standard all-purpose bonsai soil.
Straight, for cuttings and recovery
Used on its own, pumice holds enough moisture for new roots while never waterlogging, which makes it the usual choice for striking cuttings and for trees recovering from root damage or heavy root pruning.
How it compares to akadama
Akadama holds more water and nutrients but softens over the years; pumice holds less water and never breaks down. Blending the two sets how wet the root zone runs, and the pumice fraction keeps the mix open as the akadama ages.
Which bag size
This 5 litre bag suits single repots and topping up a blend. If you are mixing soil for several trees, the 10 litre bag is the same pumice in bulk.
How much a repot needs
As a guide, a 20 × 15 × 6 cm pot takes about 2 litres of finished mix and a 30 × 22 × 8 cm pot about 5 litres; the fill table above lists more sizes. Used as a third of a blend, a 5 litre bag makes about 15 litres of mix.
