How to Compost Wood Ashes? Tips to Improve Your Soil!

  • By: Melissa
  • Time to read: 6 min.
Affiliate Disclaimer

As an affiliate, we earn from qualifying purchases. We get commissions for purchases made through links in this post.

Wood ashes are alkaline and contain some nutrients that help plants. Adding the right amount to the compost will help in getting a better quality of the compost. Apart from that, it helps to raise the PH of highly acidic soil.

Compost Covered With Ashes

When added to some plants, it can affect them badly while at the same time, it has a good effect on some.

Are there chances that you are wasting something that can help in your garden?

Yes, the wood ashes you have been throwing away helps in composting. But you need to be careful. We all know too much of anything is poisonous, and in this case, too much of using wood ashes or using it on the wrong plants can mess you up.

But how will you know how much to use and on which plants? People who have been gardening for a while know which plants are acidic and need the ashes.

We have done an extensive research to show you how to use and how much you need and what plants. All you have to do is read through the article and learn all the facts you need to know about wood ashes on your compost and the soil.

Can Ashes Be Composted?

Ash is good on compost as it doesn’t contain nitrogen and can’t burn the plants. It is best on the compost pile as it is a source of potassium and lime. It helps in maintaining the neutral nature of the compost. Also, it adds nutrients to the soil.

The decomposing components in the compost can get too acidic in the decomposition process, and the ashes help balance it with its alkaline nature. However, not all wood ashes are good on compost or the garden.

Wood ashes from charcoal from grilling may have chemicals that might be harmful to the plants. Every time you are using the ashes, ensure they are wood ashes to ensure your plants are safe.

How Much Ash Should I Put in My Compost?

Ash is good on the compost heaps, but when used in excess, it can cause some issues. So, what is the right amount to use on the compost?

The best way to rate the wood ashes you use on the compost is to ensure after mixing the compost pile and ashes, you can’t see the ashes’ color.

When spreading the fireplace ashes to the garden soil, directly spread at the rate of 50-70g per square meter.

When spreading, ensure you sieve the ashes to remove that debris and have eye protection. Also, to avoid breathing the ashes, make sure you protect your face using a face mask.

Ashes Over Compost Pile

Use a pH kit to monitor the soil and the compost pile to check the pH to ensure it doesn’t go above 7.5 as that will be bad on the plant and the composting process. Wood ashes will help with the vegetable garden as it will help with clubroot.

Don’t leave wood ash you plan to use on the compost heap or the garden in the rain as ash contains potassium, which helps the flowers and the fruits. Potassium is soluble in water, and so when it rains, it will get dissolved.

When going for wood ash, take the one from young wood as it has concentrated nutrients, unlike the old wood ash.

Should You Add Ash to Compost?

Ash from wood contains calcium, magnesium, and potassium present on the tree or the original wood before burning. When you add the wood ash to a compost pile, you add the brown carbon that removes the green nitrogen responsible for producing grass clippings.

Adding ash to the compost helps a lot, as seen above, but it must be done in moderation. Wood ash is alkaline, and that feature helps in balancing the soil pH. But too much of it can cause an imbalance in the soil and affect some plants.

When ash is used in the garden that loves acid, it destroys them. It’s also good to note that wood ash should never be used with nitrogen fertilizer as it will react and release ammonia gas.

When adding ash to your compost, ensure the weather is calm as you don’t want the ash to get scattered away and end up doing zero work.

When collecting ash to use on your compost, avoid ash from black walnut known as the juglans nigra tree, found in the U.S Department of Agriculture. The environmental protection agency advises against using it as the ash can harm your garden.

Add other components to your compost to ensure it is balanced. According to experts, good compost contains three composts, including brown materials made of leaves, straws, cotton rags, and eggshells. Also, the compost should contain green materials, which include vegetables and raw fruits.

Add the ashes to the brown materials. The ash should be 1/8 of the brown material; this way, you ensure you don’t use too much, affecting the composting process.

Is Fire Pit Ash Good for Gardens?

Fire Pit Filled With Burnt Ash

You can use the fire pit ashes in your garden as long as you are sure all the ashes are from the wood, and no chemicals or stained wood are used.

Ashes from manufactured products like cola and briquettes can contain chemicals that may be harmful to the garden and people.

Also, avoid ashes from fire pits where a burn pile with bones or chemical residue was burnt as the ash will have some contents that may not be good on the crops.

Improve Your Soil Using Wood Ash

Some soil tends to be too acidic at times due to overusing inorganic fertilizer. Now when you use wood ash on such soils, you help in balancing the pH level.

Also, some crops want fewer amounts of acid in the soil, while other types want lots of acidic soils. Most vegetables thrive in soil with a pH of 6.5 to 7. When you add ash to the soil with a pH of less than 6.5, it will help the vegetables.

Wood ash helps a lot when you are using manure from cattle as the manure tends to be acidic and hence end up affecting the soil acidity, but with the right amounts of ash, you get the right amounts of pH on the manure that will help the soil and crops in return.

Fireplace Ashes for Compost

The only time you use your fireplace ash is when you are sure it’s the only wood used and the right wood with no chemicals, stain, or paint. If all the ash used was from wood, you can add on the compost as it helps create better conditions for the composting worms that help in speeding the composting process.

Compost with the right acidity is perfect for mulching vegetables before adding compost that contains ash to your crops in the garden, research, and see if the crops want more acidity or alkalinity to avoid killing the crops.

Where Not to Use Wood Ash

Never add wood ash on acid-loving crops like blueberries, or raspberries, as the ash’s alkalinity nature will affect the crops.

Also, do not apply ash to areas you intend to plant potatoes as the soil’s alkalinity will bring about potatoes scab. Don’t use wood ash on young seedlings, as you will kill them by burning their roots.


Wood ash on compost and the garden is good, but you need to be careful with the amount you add. Too much wood ash will raise the pH, which is not good for some plants, while a lower pH is also not good.

You need to get the right balance to get neutral soil to support all the plants.

Also, don’t add ash direct to the plants. At least mix it with compost or soil to avoid burning and killing the plants.