Q Can I use wood ash from my woodburner in my garden?
A Ash contains a small amount of potash. This tends to be highest when burning young, sappy growth, which is less likely to be used in a wood-burning stove. To protect its nutrient content, keep ash dry.
Ash has a similar action to lime – it raises the soil pH slightly, so it shouldn't be used around acid-loving (ericaceous) plants like rhododendrons and camellias. You can either add it to the compost heap in fine layers, so it mixes with other materials or sprinkle over the soil surface around fruit plants, fruiting veg, such as beans, and flowering plants, and fork it in.
Ash from coal fires however, shouldn't be used in the garden as it's toxic.