Weber charcoal ash in compost?

Steve Rothman

New member
Does anyone know if it's a good idea to add (cooled) ash from Weber brand charcoal to a compost bin or pile? Some places online say generally about charcoal not to use it in compost because of added chemicals that could be bad for the plants. (e.g. But the Weber products says on the bag that it is pure wood, no chemicals added. So it should be ok, no? For a composter and gardener, it seems like such a waste to throw the stuff in the trash, which is what most people say they do. Also, composters usually divide stuff into "browns" (primarily sources of common such as sawdust) and "greens" (primarily sources of nitrogen such as freshly cut grass, left over vegetables and fruits or vegetable / fruit trimming). You have to keep the browns and greens in balance to compost successfully. But there is a seasonality to what's available, e.g. lots of grass (greens) in the summer. I used to go to a lumber yard to get sawdust if I had too much greens. They'd give you a huge bag for a dollar, or if you'd sweep it up from near the saws you could take it for free. But there doesn't seem to a sawmill near me now. So when I have too much greens, I have taken to buying small pellets of compressed sawdust. Buying stuff for the composter seems really silly, given that it's all about recycling natural waste. Wood ash from a fireplace or wood stove is considered a "brown" carbon source, and excellent for composting. So it would be great if I could just start using my used charcoal ash. I use the Weber product anyway when smoking in the Smokey Mountain.

Lynn Dollar

TVWBB All-Star
I was once a composter and gave it up because it became too much work for what I got from it.

I would not use any brand of charcoal ash. Company may say its all natural, but it could still contain fillers or binders. I would not take that chance.

And yes, browns are hard to come by. In the fall of the year, I would cruise the area looking for landscape crews who were baggin up leaves. I would load up the truck with bags. Leaves are great browns for compost , but also great for my garden. By tilling in leaves, I've not added any chemical fertlizer to my garden in years.

I get a big trash can, 40 gallon or more, and then use my weedeater and make a blender out it. Put the leaves in and the weedeater will grind them up to almost a powder. They're much easier to store and the compost a lot faster. Its a lot of work, and dusty grimy work, but its worth it.

Although, this past year. I did not get any leaves. And first week of March we had a severe freeze, down to 6* and lasted for three days, and I did not have any leaves to mulch my onions and I lost all of them. I was too stubborn to go buy a bale of straw.

Leaves, they are a composter and gardener's best friend.

Chris Allingham

Staff member
This is one of those subjects where you'll find an online authority that supports whatever it is you want to do.

In principle, Weber charcoal ash should be usable in gardens. It's only wood char + a binder before burning.

My advice would be to contact your nearest university extension gardening program or local master gardening program and ask their advice. Much of using charcoal ash is dependent on the soil in your area, and they will know more than anyone about your soil. Use too much and you can really screw up your soil pH and cause other problems.


My understanding is that compost heaps can catch fire if you aren't careful.
This is true but I've only seen this happen in one case. At my church, the previous landscaper used to bag the clippings and dump them in a couple of piles next to the woods. One summer, one of the piles smoldered and caught on fire. So this happened only with a pile that constantly received grass clippins.


Compost and hay baled wet can both heat up due to fermentation and decomposition heat. I've seen entire barns burned up due to hay that was baled before it'd cured & dried out enough.

I can't see that ash, unless it was dumped in with hot coals, would run the same risk.

Steve Haack

TVWBB Member
Agreed with above, cold ash shouldn't be any more of a fire risk than dry grass.

And agreed again with Chris, your biggest concern is it'll likely change the pH of your compost pile (which you may want). Burned charcoal can be fairly alkaline.

Lynn Dollar

TVWBB All-Star
My understanding is that compost heaps can catch fire if you aren't careful.
Mine got really warm, but that's a good thing, says the bacteria are working at breaking down the substances.

I suspect a pile could spontaneously combust. Except mine was wet most of the time, I kept it like a sponge. It needs water, heat, bacteria from soil, and the right greens and browns.