How to Use Wood Ash in the Vegetable Garden


Benefits of Wood Ash in the Garden

If you have a fireplace or woodstove, use wood ashes to improve garden soil! Wood ash is full of nutrients that plants need, such as potassium and phosphorus, so it’s great for using on the vegetable garden. But it’s important to know where not to use it, too. In this short video, we show you when, where and how much wood ash to apply to keep your plants in tiptop condition.

Wood ash is particularly useful for fruiting plants.

Ash from hardwoods like oak and beech are best as they contain more nutrients than ashes of softwoods like pine. Avoid using the ash from coal or treated timber, which could be harmful to your soil and plants. 

The nutrients in wood ash are soluble. They must be kept out of the rain so they don’t wash out. Use a container with a close-fitting lid to keep your wood ash dry until you’re ready to use it. 

Composting Wood Ash

Wood ash is alkaline, so it can help to reduce the acidity of a compost heap. This creates better conditions for composting worms and results in compost that is perfect for mulching around vegetables. 

Add thin layers of wood ash to your compost heap no more frequently than every six inches of material.

Using Wood Ash on Garden Soil

Most vegetables need a pH of 6.5 to 7.0. If your soil’s below 6.5, fork or rake wood ash to help raise the pH. You can test your soil using an inexpensive test kit to find out its pH. 

Wood ash is about half as effective as lime in neutralizing acid. As a general rule, scatter about two ounces of ash to every square yard. Do this on a still day in winter and wear gloves to protect your hands. 

Brassicas such as cabbage and Brussels sprouts are best grown in a more alkaline soil. Apply wood ash the winter before planting, or around actively growing plants. 

Wood ash is high in potassium, which helps flowering and fruiting, so it’s ideal to use around most fruit bushes and around fruiting vegetables such as tomatoes. 

Avoid using wood ash around plants that require an acid soil such as blueberries. Don’t let it come into contact with seedlings or use on potato beds, as alkaline soil encourages potato scab.

Wood ash would need to be used in huge quantities to make your soil too alkaline for most other crops, but it would be worth re-testing your soil’s pH every two years to check it doesn’t go above 7.5. 

See MORE ways to use wood ashes in the home and garden.


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About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

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Melanie (not verified)

3 years 7 months ago

I spread the ash from my wood stove on my lawn and it has greatly improved the grass. I also use it in the chicken run where the girls like to dust bathe as it's supposed to also help with mites and such. No mites since I've been using it the last 4 years.

susie (not verified)

3 years 7 months ago

we use a pellet stove, the pellets are soft wood wood that be good in all of what you were talking about

Alvin B Smith (not verified)

4 years 8 months ago

Then why do blueberries always do so well immediately after a forest fire? And, tomatoes are known to prefer acid soils.....

Elaine Carey (not verified)

5 years 6 months ago

I use my ashes from the fireplace every year to put under my bushes and some trees. Since my soil is very acidic from the many pines in the yard, I think the ashes helped with growth and some blooms.

Matthew (not verified)

5 years 6 months ago

Does wood ash have any pest repelling properties? I’d love to find a natural remedy for killing/repelling ants, DE doesn’t seem to work. All the ants have decided to move their nests into all my outdoor (and some indoor!) potted plants. They don’t seem to be harming the plants, but their numbers are getting out of control. Any advice would be appreciated!

Ward (not verified)

2 years 7 months ago

In reply to by Matthew (not verified)

I buy the rubber watering pans from Tractor Supply to put under my large pots. There are several sizes and range from $10 to $15. I keep water in the pans which waters the plants and keeps the ants out.

Lilbit (not verified)

2 years 7 months ago

In reply to by Matthew (not verified)

Buy some borax (Remember “20 Mule Team Borax” detergent our grandmothers bought from the grocery store & used for washing?). Sprinkle it around the house or mix with a little sugar to draw the ants. They will carry the borax back the the nest. It will take several weeks to kill off the nest.

Roger (not verified)

5 years 2 months ago

In reply to by Matthew (not verified)

Ants can be beneficial but if you are having a problem with them use a Boric Acid powder along their trails. They will take it back to the colony and you'll soon see them disappear. It is relatively cheap and not harmful to humans and pets. I picked up several bottles at the dollar store to have on hand when needed.

eddy (not verified)

5 years 6 months ago

very good thank you

Ben (not verified)

5 years 6 months ago

In reply to by eddy (not verified)

Ants perform many of the same soil improving functions as worms do, and can be even more effective and prolific due to their numbers. Their tunnels and chambers aerate and help drain the soil, they break down organic matter into ideally sized particles filled with beneficial microbes from their gut, and they can help moderate soil pests. If they are not fire ants, or getting in your food, or ranching aphids, I'd be thankful for them. Carpenter and other ants also get a bad wrap regarding structure damage, as they only occupy already rotten, wet structurally weakened wood, causing little additional harm, and their trails back and forth to their chambers are giving you an indication of a problem that you may have otherwise not known about until it collapsed from rot.