Can You Compost Ashes? (If Yes, Then How and When?)

Those cozy winters when all you want to do is sit with a cup of coffee in your hand near a fireplace or have a get-together with friends around a bonfire, two things that you’re left with after both events are contentment and some wood ash.

Large amounts of wood ash are produced the same way, and you must wonder whether you can put those ashes into some use. And those who have a green thumb might ponder if wood ash can be composted. So, buckle up! We’ll bring all the answers to you here.

Yes, you can compost wood ash as long as it is from untreated wood. It is a brown compost material that raises soil pH and contains 12 of 15 essential nutrients. Sprinkle wood ash while adding new material to the compost pile and ensure it doesn’t make up more than 5% of the compost.

Well, that’s a lot of information in a concise form, and you must keep some things in mind before putting ashes into the compost pile. But before that, let’s understand what wood ash is.

What is Wood Ash?

Wood Ash on Ground

Wood ash is the powdery substance obtained from burning wood. Ash is the gray-colored tiny powder, and charcoal is the black remnant. They are burnt incompletely, and together they constitute wood ash.

So, ashes are the solid residues of fire. But how should you compost these unburnt remains? Let’s find out!

How to Compost Ashes?

Composting ashes is not a difficult task to achieve. But you should do it carefully. It can be said that ashes are good brown material for the compost, but you should add them in a regulated manner.

You can compost ashes through Hot Composting and Cold Composting.

1. Composting Ashes through Hot Composting

Wood Ash for Plants

Wood ash can be composted via hot composting through a compost heap or a hot compost bin. Here is a step-by-step procedure to compost wood ash.

Step 1: Reduce the Size of Greens and Browns

Take the Nitrogen-rich and Carbon-rich materials and chop them into small pieces. Reducing the size accelerates the decomposition process.

Step 2: Add Chopped Brown Material to the Compost Pile

Add the Carbon-heavy browns to the bin or start the pile. Materials rich in Carbon are dead leaves, twigs, pine needles, newspaper, etc. These materials add bulk to the compost and improve structure.

Step 3: Add Green Material

Add a layer of Nitrogen-containing material like grass clippings, green leaves, tea bags, hair, kitchen scraps including fruit peels, used eggshells or shrimp shells, bread, coffee grounds, etc. Green Materials are responsible for the heating up of the pile.

Step 4: Add Ashes

Sprinkle a small amount of wood ash on the compost pile.

Step 5: Add Water

Sprinkle some water or add it in small amounts to maintain the moisture level of the compost.

Step 6: Repeat the Process

Continue layering alternately with greens and browns, along with the addition of ashes. Keep on adding ashes till the pile is active.

Step 7: Turn the Pile After 2 Weeks

Give your compost pile turnings every two weeks to facilitate aeration.

And you’re all good to go! Your compost will be ready in about six weeks by hot composting. This method is a relatively faster process but requires a bit of maintenance. For a less-maintenance method, go for cold composting. 

2. Composting Wood Ashes through Cold Composting

Adding Wood Ash in Compost

Cold composting usually takes longer and requires patience, but the good thing is that you won’t have to observe your compost pile now and then. Below is a step-by-step guide for composting wood ash through the cold composting method.

Step 1: Add a Layer of Brown Material

Add the brown material to the compost pile. Adding brown organic material will increase its Carbon content.

Step 2: Add a Layer of Green Material

Add a layer of Nitrogen-heavy green organic material.

Step 3: Add Ashes

Add the ashes to the compost pile in a small amount in fall or late summer to allow them to compost before the growing season.

Step 4: Add Water

The addition of water is a must to increase the moisture level.

And that’s it! All you need is a little patience, and your compost will be ready in about six months to a year with all the benefits of ashes.

Sprinkle ashes to the amount that it makes only 5% of the compost. 

So, whenever you have a lot of ashes left at your fireplace, don’t fret. Just add them to the compost pile by following the above methods. For more information about different types of composting methods, join us here.

Benefits of Composting Ashes

Applying Wood Ash on Soil

There are many benefits of adding ashes to compost. And understanding the pros will encourage you to save those ashes from the wood stove or fireplace for your plants instead of discarding them.

  • Eco-Friendly Way of Disposing: Composting ashes is an environment-friendly way of disposing of the ashes that otherwise would’ve ended up in landfills.
  • Improves Composition: Wood ashes are a good source of Potassium, Calcium, Phosphorus, and Magnesium. They also contain Iron, Manganese, Boron, Copper, Zinc, Molybdenum, and Sulfur. All of these improve the quality of the soil and make it more suitable for plants.
  • Raises pH: Adding ashes to compost will increase the alkalinity of the soil.

Areas with heavy rainfall tend to have more acidic soil. Therefore, adding ashes to the compost and applying it to the acid soil will benefit the maximum by making it alkaline. It is a superb substitute for lime.

  • Soil Amendment: It is an excellent alternative to lime that is added to correct soil acidity.
  • Repels pests: Applying compost containing ashes to the soil will deter pests from attacking like snails, slugs, etc.
  • Increase Nutrient Holding Capacity: Composting ashes improves the soil’s nutrient holding capacity by increasing the particles’ surface area.

With these myriad advantages, who wouldn’t compost ashes?

And as for the disadvantages, there aren’t many, except that excessive usage will hinder plant growth and development. 

Tips for Composting Ashes

Soil PH Meter Checking the Soil PH Value

These tips will help you compost ashes efficiently and easily to help your plants thrive.

  • Don’t Mix Ashes with Nitrogenous Fertilizers: You should not use wood ash with Nitrogen fertilizer like ammonium sulfate, ammonium nitrate, and urea with ashes. Adding these two together will lead to the production of ammonia gas.
  • Perform Soil pH Test: It is recommended to test your soil’s pH before adding composted ashes to them. This will help avoid excessive alkalinity in the soil.
  • Don’t Burn Wood Especially: Don’t burn wood for the sole purpose of having ashes. This will harm the environment more than doing good to your compost.
  • Add Small Doses of Ash: Avoid adding heaps of ash to the pile. Instead, sprinkle them and add them between the layers of green organic matter and brown organic matter.
  • Let the Ash Cool Down: Allow the wood ashes to cool down before adding them to compost, as hot ash can pose the risk of fire to the beneficial microbiota in the soil.

Precautions While Composting Ashes

Keeping specific points in mind will not only give high-quality compost but also will help you avoid problems associated with composting them. Therefore, taking note of them is essential!

  • Wear Personal Protective Equipment (PPE) like gloves, mask, etc., to avoid skin irritation and inhaling ashes.
  • Don’t add the compost made of ashes to acidic soils or acid-loving plants like blueberries, Azaleas, or newly planted seeds and seedlings.
  • Avoid using excessive amounts of composted wood ash as it will turn the soil alkaline and increase the quantity of heavy metals in the soil. This will also inhibit plant growth.
  • Don’t use ash from barbeque grills, plywoods, painted woods, pressure-heated woods, or charcoal ashes.
  • Avoid using ash if the weather is windy.
  • Avoid using ash from a black walnut tree.

So adding ashes to your compost is not a big deal. Just follow the steps of composting, take precautions, and follow tips to have the best compost out of ashes for your plants and garden!

Can I use ash from paper in compost?

Yes, you can compost ash from paper, ash from straws, and ash from untreated wood in compost.

Can I compost ash from cigarettes or cigars?

No, it is not recommended to compost ashes from cigarettes or cigars.

Can I use composted ash for the vegetable garden?

Yes, you can use ash in compost for the vegetable garden. However, it is recommended not to apply ash to edible plants.

How can I apply ash to my garden except by composting?

Other ways to apply ash to the garden except composting are top dressing and incorporation into the root zone.

What is the best time to add wood ash to the garden?

The best time to add wood ash to the garden is autumn.

Can we add lump charcoal to compost?

NYoushouldn’t add lump charcoal, charcoal briquette, or ash from the charcoal grill to the compost.

Therefore, you can now save those fireplace ash and add them to your garden soil through compost. It is an excellent way of recycling wood ash instead of discarding them in landfills. Just remember not to use that bbq ash, coal ash, charcoal ash, or ash from treated wood or stained wood, and you’re good to go!

Mulch is another organic material that can be used to make healthy compost. However, people are skeptical about using dyed mulch. If you are unsure, too, then without further ado, hop to our guide on composting dyed mulch to learn some exciting information!

  1. Wood Ash: Using in the Garden – The Royal Horticulture Society
  2. Practices for Wood Ash as Agricultural Soil Amendment – University of Georgia Extention