Adding Wood Ash in Compost: Good or Not?

You can definitely add wood ash to your compost or directly into the soil to benefit the plants as Wood Ash contains a lot of nutrients that benefit the plants but before you do that, it’s important to know the nature of ash and how it affects the plants. Wood ash is also a remedy for excessively acidic soil.

What is Wood Ash?

Wood Ash is a grey remains which is left behind when a wood piece is burnt completely. Just for clarification, we’re here not talking about Charcoal used in grills, we’re specifically talking about wood ash. Charcoal can contain other chemical elements which manipulate their temperature while heating so those chemicals can harm the plants.

You have to make sure that the Wood which is turned into Wood Ash is not painted or treated in any way and is pure naturally occurring wood.

Can you compost Wood Ash?

Yes absolutely! Why not. Wood Ash has been used in composting for a long time and it has shown its benefits. However, there is a certain types of wood ash which are better than others for plants and composting.

Can You Compost Coal Ash?

The answer is really dependent on the Coal you want to compost.

Natural Coal Extracted from Mines: You can not compost this type of coal which is extracted from the earth. It contains toxic elements like Sulphur and other metals which harm the plants.

Coal made after Burning Wood: This type of coal can be used if you are sure that the coal is not processed or contains anything that is unnatural for wood.

Process of Composting Wood Ash

Ash comes in the category of browns as the carbon content in the ash is very high because ash is prepared after the burning of wood. So we usually make sure to have more nitrogen-based things in the compost in which we’ll be mixing ash.

Here are some general guidelines for composting wood ash:

Collect the ash: Collect the wood ash in a metal container with a lid, so that it is easy to transport and store. Only use ash from clean, untreated wood which is chemical-free. Do not use ash from natural coal or charcoal, as they contain chemicals that are harmful to plants. Use ash which you’re sure about if its chemical free and unprocessed.
Store the ash: Store the ash in a dry, covered area away from moisture. This will prevent the ash from getting wet and clumping together, which can make it more difficult to use in your compost.
Add the ash to your compost: Add the ash to your compost in small amounts, mixing it in thoroughly with other compost materials. A good rule of thumb is to use no more than 1/4 inch of ash per compost layer. Or just add 10% of ash to compost. Too much ash can raise the pH of the soil, making it too alkaline for plants to grow.
Monitor the pH: As you add ash to your compost, monitor the pH levels. You can do this by using a pH meter or testing kit. Ideally, the pH of your compost should be between 6.0 and 7.0. If the pH is too high, you can add more organic materials to the compost to lower it.
Use the compost: Once your compost is ready, use it to fertilize your garden or lawn. The wood ash in the compost will help to balance the soil pH and provide important nutrients like potassium, calcium, and magnesium to your plants.

By following these guidelines, you can safely and effectively compost wood ash, and turn it into a valuable resource for your garden.

Benefits of Wood Ash in Compost

Wood ash can provide a number of benefits when added to compost:

Nutrient Source: Wood ash is rich in nutrients such as potassium, calcium, and magnesium, which are important for plant growth and development.
Alkalinity: Wood ash has an alkaline pH, which can help balance acidic soil, making it more suitable for a wide range of plants. But make sure that the plant you wanna grow is not acid-loving if you’re adding wood ash compost to it. We have added a list of plants which like wood ash compost, you’ll read it further in the article.
Pest Control: Wood ash contains compounds that can repel certain pests, such as slugs and snails, when wood ash is added to the soil.
Odor Control: Wood ash can help reduce odors in the compost pile, particularly if the compost is made up of high-nitrogen materials, such as food scraps and too many greens.
Moisture Absorption: Wood ash can help absorb excess moisture in the compost pile, which can help prevent the growth of harmful bacteria and maintain moisture levels.
Compost Structure: Wood ash can help improve the structure of the compost, making it more crumbly and easier to handle and making it better for the plant’s rooting system.

Drawbacks of Wood Ash Compost

While wood ash can provide some benefits to compost, there are also some potential drawbacks to consider:

Alkalinity: As mentioned, wood ash has an alkaline pH, which means that adding too much can increase the soil pH, making it less suitable for acid-loving plants. This can result in nutrient deficiencies and other problems. We have added a list of plants which like acidic environments, you’ll read it further.
Nutrient imbalances: While wood ash is a good source of potassium and calcium, it lacks other important nutrients, such as nitrogen and phosphorus, which are also essential for plant growth. Using too much wood ash in compost can result in nutrient imbalances that can harm plants.
Contamination: If the wood that the ash came from was treated with chemicals or other contaminants, those contaminants can end up in the compost and ultimately the soil, posing a risk to plants and potentially to humans if the plants you’re growing are eatables, so just avoid any wood ash you’re not sure about.
Odor: While wood ash can help reduce compost odors, it can also create its own distinct odor that some people find unpleasant.
Dust: Wood ash is dusty, and can easily enter your body while you’re breathing which can be a problem for people with respiratory issues, such as asthma.
Inconsistent quality: The nutrient content of wood ash can vary depending on the type of wood burned, the temperature at which it was burned, and other factors. This can make it difficult to know exactly what you are adding to your compost and how it will affect your plants. So it’s better to get the ash checked for its nutrients or just add wood ash in very low quantities.

Nutrients in Wood Ash

Calcium
Magnesium
Phosphorus
Manganese
Zinc
Potassium
Chromium
Copper
Nickel

Suitable Plants for wood Ash Compost

Wood ash is a good source of potassium, calcium, and other nutrients that can benefit plants, but Wood Ash is also Alkaline in nature, which means it can raise the pH level of the soil over time. Here are some plants that tend to tolerate or even benefit from the alkalinity of wood ash:

Best-suited plants for wood ash compost

Fruit trees, such as apple, peach, and cherry trees
Tomatoes
Peppers
Melons
Squash and pumpkins
Cucumbers
Asparagus
Rhubarb
Lavender
Lilacs
Grapes
Roses
Carrots
Beets
Spinach

When using wood ash as a soil amendment, it’s important to use it sparingly and to mix it thoroughly with the soil to prevent pH imbalances. It’s also a good idea to avoid using wood ash around acid-loving plants like blueberries, azaleas, and rhododendrons and a few more are given below:

Avoid using Wood Ash Compost With These Plants

Azaleas
Blueberries
Rhododendrons
Hydrangeas
Camellias
Gardenias
Ferns
Heather
Holly
Japanese maple trees
Magnolias
Pine trees
Roses (some varieties)
Sweet potatoes
Wildflowers, such as lupines, bluebells, and buttercups.

Can We Add Wood Ash Directly into the Soil

The answer is YES!

You can add Wood Ash directly into the compost but it’s not wise to dump a lot of wood ash into the soil. If you have tools for pH measurement and your soil is very acidic, then you can add a lot or the required amount of ash into the soil to shift the pH of the soil towards or between 6-7.

What not to do with Wood Ash!

If you’re using nitrogen fertilizer, then do not use wood ashes. It might react and produce ammonia.

Also, do not handle ash without an eye mask and gloves. Do take proper precautions before dealing with any sort of fertilizer or compost.