Description
Scoria 7mm is the fine grade of porous red volcanic rock, sized for pot top-dressing, small garden beds and detail work where 20mm pieces would look out of proportion. It is also used for decorative ground cover, pathways and fine drainage layers.
Like the 20mm grade it is light for its volume. The red-brown colour is the rock’s natural mineral colour, so there is no dye to fade, though it may dull with dirt and weathering. On pots, a thin top-dressing also helps reduce evaporation from the potting mix surface.
A quarter cubic metre goes a long way at this grade: it covers about six square metres of bed at 40mm, or top-dresses a large number of pots.
Technical Specifications
| Material | Porous red volcanic scoria |
|---|---|
| Size | 7mm |
| Application | Fine decorative cover, drainage |
| Sold as | Loose, by the cubic metre in quarter-m3 steps |
| Collection | Pickup from Keilor East, Melbourne |
Where to Use
- Pot plant top-dressing and container gardening
- Detailed garden bed decorative cover
- Smaller-scale drainage applications
How to Apply
- Prepare the base – clear the area or pot, and lay a weed mat for garden bed use if wanted.
- Spread to an even depth – distribute evenly across the bed or pot surface.
- Grade for drainage – where used in a drainage application, ensure adequate fall.
- Finish the top-dress – for pots, spread a neat, even top-dressing layer around the plant base.
- Top up as needed – replenish over time as material settles or is displaced.
Important Notes
- Natural mineral colour, so there is no dye to fade; it may dull with dirt and weathering.
- Suited to smaller-scale and detailed decorative use given its fine grade.
- Pickup from Keilor East (Melbourne). Sold loose by the cubic metre in quarter-m3 steps; part loads of a quarter, half and three-quarter cubic metre are available.
- Light by volume: roughly 0.8 to 1 tonne per cubic metre, about half the weight of solid crushed rock.
- Crushed stone dust can contain crystalline silica. Keep the material damp when spreading or sweeping, avoid breathing the dust, and wear a P2 mask if it is dry and dusty.
- Further reading: Scoria (Wikipedia).
