Plant Doctor Archive

What to do with wood ash?

CAN I put wood ash straight from the fireplace and incinerator on my garden? What plants would it help?

THE main nutrient wood ash provides is potassium, which it contains in relatively low amounts compared to compost and most other fertilisers. You can use it straight from the fireplace but it generally has a high pH so spread it sparingly around the garden and avoid using it near acid-loving plants like rhododendrons (right), gardenias and kalmias. Spreading it can be tricky, as it's very fine and tends to blow around in the slightest breeze.

The easiest way of putting wood ash to good use is in the compost heap - spread a layer of ash with grass clippings or vege scraps. This way, the alkaline nature of the ash helps the composting process and, when you turn the compost heap, it mixes in well.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.