River sand 0/3 mm - 10 lt pack

What it is and where it comes from

It is a natural inert material. It is formed by the breakdown of rock carried out by rivers, which over time round off the grains and sort them by size along the watercourse. This 10-litre pack contains river sand with a 0/3 mm grain size, therefore a fine fraction, used both in preparing the seed bed for lawns and in blending specific bonsai soils.

How it behaves in the pot

Sand does not hold water. The grain is compact and inert: water wets it and runs straight through, leaving air between one particle and the next. In a mix that tends to close up, this is precisely its job: to open up the drainage channels and prevent irrigation water from sitting at the bottom of the pot.

The second reason it is used is stability. Unlike fired clays, the mineral grain does not break down or turn to paste over the years, so the porosity it provides on repotting day is the same you will find at the next repotting. It should be noted, however, that the 0/3 mm grade also includes the finest fraction: if poorly sieved, the dust settles and works against drainage instead of helping it.

Features

• Material: river sand, natural inert material of fluvial origin
• Grain size: 0/3 mm
• Pack: 10 litres
• Role in the substrate: drainage and root development
• Other uses: seed bed for lawns

Which grade and for which plants

The 0/3 mm is a fine grade, suited to small pots and shallow bowls where a coarse material would leave excessive gaps: shohin, mame, plants in training and seedlings. In medium-sized bonsai it goes into the body of the substrate as a lightening component, not as a base.

It pairs well with bonsai clays and volcanic materials, and is especially helpful for species that will not tolerate waterlogging, from conifers to olives. The same logic applies when using it as sand for potted plants: it serves to open up a soil that is too dense, not to replace it. At the bottom of the pot, if you are after a genuine drainage layer, a coarser grade is a better choice.

How to use it when repotting

First of all, sieving. The 0/3 mm fraction carries dust and very fine particles: passing it through a mesh and rinsing it, if needed, removes what would otherwise seal the pores of the substrate. Many people prefer washed river sand for exactly this reason.

In the pot it is blended with the other components before filling, not layered separately. Once the root ball is in place, work the mix down between the roots with a chopstick, moving from the centre towards the rim, without pressing with your fingers. Then water thoroughly, until the water runs clear from the drainage holes.

Frequently asked questions

Is river sand suitable on its own as a bonsai substrate?

No. It holds neither water nor nutrients, so on its own it would force you to water several times a day. Its place is within a mix, alongside components that store moisture, where it does the job of keeping the substrate open and free-draining.

Doesn't the 0/3 mm grade risk compacting the soil?

If it is not sieved, yes: the dusty part settles into the spaces between the coarser grains and reduces drainage. Once the dust is removed, the 0/3 mm remains a fine grade suited to small pots, where a coarse sand would leave gaps that are too wide between the roots.

How many litres does this pack contain and how many pots will it fill?

The pack holds 10 litres of 0/3 mm river sand. As it is a mix component rather than the main substrate, it goes a long way: it covers the needs of several repottings of small and medium plants, depending on how much you choose to include in your own blend.

What is included

• 1 pack of river sand
• Grain size 0/3 mm
• Capacity 10 litres

If you prefer to measure out the components yourself, you can create your own blend on the made-to-measure soil page.