Ash in the Winter Compost Pile
Wood ash can be a great addition to the garden. It contains potassium which is a vital nutrient for your garden crops.
Just as it does in humans, potassium regulates plants’ water balance, and has a part in transporting food within the plant and creating sugars and starches. Without enough, vegetables are more vulnerable to drought, frost, pests and diseases.
I generally get 1 pound of ash for every 100 pounds of wood burned.
Ash in the Compost Pile
Wood ashes make a great addition to the compost heap, where they’ll aid fertility. Ashes are alkaline and will raise soil pH. This can affect the bacteria, fungus, and worms at work. It’s better to sprinkle on a layer every so often.
If you compost a lot of acidic material, such as fruit waste, ash will help regulate pH and reduce the need to lime the vegetable plots at a later date.
Ash as a Substitute for Lime
Hardwoods generally produce more ash and contain more nutrients than softwood. I burn 95% Oak and 5% Cherry hardwood.
Ash from a cord of oak weighing approximately 3,600 pounds will provide enough potassium for a garden 60 x 70 feet and should raise the soil pH slightly. That 3,600 pounds of wood makes approximately 36 pounds of ash.
It’s a good idea to test the pH of your soil before adding the ash and three to six months after, to check on its effect. It wouldn’t hurt to check up on the potassium content while you’re at it. There’s no point in adding ash to a soil that’s already high in potassium, as too much can affect the plants’ take-up of other nutrients.
Where Not to Use Wood Ash in the Garden
Being alkaline, wood ash obviously isn’t an ideal addition if your soil already has a pH of 7.5 or greater. There’s no point in spreading it around acid-loving plants such as blueberries or azaleas. Nor is it recommended for areas where you intend to grow potatoes (much though they enjoy potassium) as increased alkalinity can encourage the fungus, potato scab.
Adding Ash Directly to the Soil
Sprinkling ash straight onto the soil deters slugs and snails, but the moment it gets wet, this effect stops.
I generally add ash to the soil in winter, but it can be spread around at other times. Root vegetables such as carrots and parsnips plus peas, beans and fruit all appreciate ash.
- Keep ash dry before use.
- Test your soil before spreading large amounts around.
- Use it in particular around root vegetables, peas and beans, fruit trees and soft fruit bushes.