Basalt rock dust for growers
A few handfuls of crushed volcanic rock, spread on the soil. Here is what basalt rock dust is, how growers use it alongside electroculture, and where to buy it in the UK.
What it is
Basalt is a dark, fine-grained volcanic rock. Crushed to a powder, it is sold as rock dust or basalt fines for use on soil and in compost. It contains a range of minerals and trace elements, and because it is ground rock rather than a manufactured fertiliser, it breaks down slowly in the soil over time.
Why growers use it with electroculture
Basalt is often described as paramagnetic, and paramagnetic materials feature in electroculture thinking, which is why you will see the word on our antenna pages. Many growers spread rock dust around an installation to feed the ground itself, working alongside the antenna and the earth connection.
How it is usually used
Suppliers commonly suggest around half a kilo per square metre as a top dressing, which is roughly what a 20 kg bag covers over 40 square metres. It is scattered on the soil surface and raked in lightly, or sprinkled into compost heaps and wormeries. It can go on at any time of year, and many people choose winter so rain can work it in. Always follow the instructions on the bag you buy, and if you are unsure what your ground needs, a simple soil test is a good place to start.
Spreading it safely
Rock dust is very fine, so avoid breathing it in. Wear a dust mask and eye protection when spreading it, choose a still day or dampen it first, and keep children and pets away until it has been watered in.
What to look for when buying
Check what rock it actually is. Some products are sold as "volcanic rock dust" without saying whether they are basalt, so ask the supplier if it matters to you. Also look at where it comes from and how fine it is: the finer the grind, the faster it weathers. For larger areas, local quarries sometimes sell basalt fines in bulk, which can work out cheaper per tonne than garden-centre bags.
Where to buy in the UK
We do not sell rock dust and earn nothing from these links. They are here for convenience, not as endorsements. Prices were checked on 7 October 2026 and will change.
| Mr Fothergill's | REMIN volcanic rock dust, 10 kg bags, around £15 plus delivery. |
| Harrod Horticultural | REMIN volcanic rock dust in 20 kg bags and 1-tonne bags, handy for allotment groups and larger areas. |
| Marshalls Garden | REMIN volcanic rock dust, 10 kg. |
| QuickCrop | Basalt from Scottish quarries in 1 kg bags. This is an Irish shop, so check that it delivers to your address. |
Next steps
New to electroculture? Start with how antennas actually work, watch our installation videos, or see the equipment in the shop.