How long they stay hot
Ash is an excellent insulator, which is exactly the problem. Embers buried in a bed of ash can stay hot enough to ignite for two full days, and in a deep stove that has run all weekend, longer. The surface being cool tells you nothing about what is underneath.
The safe method is a metal ash bucket with a lid, kept outside on a non-combustible surface, well away from the house, the fence, the shed and anything wooden. Plastic bins melt, and every year fire services attend house fires started by ashes in a plastic bin or a cardboard box in a porch.
Wait 48 hours as a minimum, and rake through before you bag anything. If there is any warmth at all, wait longer. Water works if you need it faster, but it turns ash into a heavy, caustic sludge that is unpleasant to handle and heavier to move.
- Assume 48 hours minimum
- 72 hours for a deep stove bed
- Metal container with a lid, not plastic
- Never a cardboard box or paper bag
- Store it away from the house
- Cold to the touch throughout, not on top
Which bin
Cold ash from wood, coal or smokeless fuel goes in the general waste bin, not recycling and not the garden or food caddy. Bag it first — loose ash in a wheelie bin blows everywhere when the lorry tips it and coats everything in the bin.
It is worth double-bagging, because ash is fine, dense and abrasive and a single bag splits easily. Keep the weight sensible too: a bin bag full of ash is much heavier than it looks and bin crews have to lift it.
Barbecue ash follows the same rule but with more urgency, because disposable barbecues in particular hold heat under the tray long after the top feels cold. Douse thoroughly, wait until it is cold throughout, then bag it.
Coal bunker or stove coming out?
Old bunkers, grates and garden debris cleared in one visit across Scotland.
Wood ash in the garden — genuinely useful
Ash from untreated wood is a real garden resource. It contains potassium and calcium, raises pH on acidic soil, and much of Scotland's soil is on the acidic side, so a light dressing is often beneficial rather than merely harmless.
Use it sparingly — a light scattering, worked in, not a heap. It is alkaline, so keep it away from acid-loving plants: rhododendrons, azaleas, blueberries, camellias and heathers will all suffer. It also works as a slug deterrent when dry, though it stops working the moment it rains.
Store it dry before use. Wet ash leaches its potassium away and sets into a solid lump, which is neither useful nor easy to break up.
Coal ash is not the same
Ash from coal and smokeless fuel should not go on the garden or into compost. It contains sulphur and heavy metals in concentrations that are fine in a bin and not fine in soil you grow food in, and it does not have the nutrient value that makes wood ash worth using.
The same applies to ash from anything painted, treated, varnished or manufactured — old fence panels, treated decking, chipboard, MDF and pallets. Burning treated timber is a bad idea in the first place, and the resulting ash concentrates whatever was in it.
If you are clearing a coal bunker, an old stove, or a garden full of ash and burnt debris, that is straightforward for us to take as general waste — see garden rubbish clearance and rubbish removal.
