Most people here will probably say no they are not good for your compost. Most charcole brickets are treated with petro-chemical products to get them to light and burn easily. I don't know how much residue of these nasty things are left in the ashes. I also don't know what the best answer as to what to do with them are since I don't see putting them in the trash as being a good option.

Everything I have read says to put them in the trash can (bagged first). The charcoal companies will tell you to trash them too.

Not a good product to use in your compost pile or garden because of the hazardous materials that are in those briquets.

As mentioned above, the current advice is not to use them. A few who think the cautions are overly conservative do use them in ornamental plantings, but keep them away from food crops.

There have been several discussions of the benefits of charcoal in the garden, the most recent being this one. Hope you find it interesting.

Catherine

Here is a link that might be useful: Discussion of Charcoal

Depends on what kind of charcoal. If it is the type that has additives including lighter fluid, then I wouldn't use it in compost (I do spread it on top of my flower beds, they don't seem to mind. But if it's pure charcoal (which is just burnt wood) then you can use it.

I agree with buford. It depends upon the charcoal. If its natural wood charcoal then its okay to put the ashes in your compost. Check the ingredients and the label.

I have used Kingsford charcoal for a patio hibachi, going through maybe 10 - 15 x 18 lb bags a summer. I just rinse this out, and the water flows off the concrete patio and onto the grass, and it has made no difference what so ever after 10 years of doing so.

This fall, I bought a couple 18 lb bags of Kingsford "mesquite" charcoal to roast chili. The ash from that stuff turned the grass yellow. It has since recovered, but still.

So, charcoal ash varies. If this is from the summer accumulation, its probably salty.

The charcoal I use is regular Kingsford brand I get at Sams Club. It isn't the kind that you can light with a match and I don't use lighter fuel. Maybe I'll just use it on the flower beds.

The most popular charcoal, the brickets, have a lot of stuff added to them to hold them together, not stuff you want in your soil. If you use the charcoal that does look like actual pieces of wood, unprocessed charcoal that might be okay if the fats from what you grill are all burned off.

I have checked with Kingsford but they never went into that kind of detail. That's pretty interesting. In any case I never suspected they used anything that might volatilize and become a problem with hot meat. However, for whatever reason, they specifically do not recommend using their products in the garden. Now, using their product and using the ash from their product are two different things, aren't they? Anyway, here is a couple excerpts from their FAQ.

I've heard of using charcoal to absorb odors. Will your product work for this?
No. Both Kingsford and Match Light briquets contain ingredients other than charcoal to make them efficient cooking fuels. Use "activated charcoal" for deodorizing. This can be obtained at plant nurseries and pet stores.

Can you use this product as compost or fertilizer?
No. Both Kingsford and Match Light briquets contain ingredients other than charcoal to make them efficient cooking fuels. Charcoal briquets do not aid in the breakdown of organic matter.

If they had answered, "yes," to these questions they would sell a lot more of their product. For that reason alone I am going to respect their thoughts on the subject.

Hey guys, unless you have dozens of grills which I'm guessing no one does, were probably talking probably 20 or so briquettes of charcoal and a few scoops of gunk from the bottom . Given the quantity here if there is any question for potential harm just throw it away - done.

david52 (hi, Dave!) wrote & quoted (my emphasis added) on Wed, Nov 7, 07 at 15:34:

I tried to find what kind of binder they used, and found this:

Mineral char (Heat source)
This is a geologically young form of coal with a soft, brown texture. It helps Kingsford burn hotter and longer than a plain charcoal briquette. As with the wood, Kingsford heats this material in an oxygen-controlled environment, eliminating water, nitrogen, and other elements, leaving behindalmost pure carbon.
Mineral carbon (Heat source)
This is anthracite coal, the old, hard, black stuff once commonly used for home heating. It helps Kingsford burn hotter and longer than a plain charcoal briquette. It's already 86-98% pure carbon, but once again, Kingsford processes it in an oxygen-controlled environment, leaving behindalmost pure carbon.
What exactly is coal, you ask? "Nasty stuff," some folks say. Well, coal is a fossil fuel, most of which was formed more than 300 million years ago. To make a really, really long story short: Plants and trees died, sank to the bottom of swampy areas, accumulated into many layers, then geologic processes covered the stuff with sand, clay, and rock, and the combination of heat and pressure converted it into what we call coal.
So, coal is really old plant material that can be processed into almost pure carbon. Charcoal is wood that is burned down into almost pure carbon. Not much difference, in my book. End of coal lesson.

Not much of a difference, no. But there is a difference. And unfortunately, this difference can cause a very serious set of problems if you use coal ash -- not plain charcoal ash -- anywhere in a garden.

Coal ash contains small but harmful amounts of toxic metals, many of which are usually referred to as heavy metals. Including "arsenic, lead, mercury, nickel, vanadium, beryllium, cadmium, barium, chromium, copper, molybdenum, zinc, selenium and radium." (quote from the Wikipedia article on coal, link below.)

Some of these metals and substances leach out of soil. Others don't. Some concentrate in soil, in plants, and then further concentrate (and accumulate) in humans who eat the plants. And while a few of these substances are helpful to plants and humans in very, very small amounts, most of them are not. Even the helpful substances can be harmful beyond trace levels.

Keep in perspective that 1% (or 1/100th of 1%) of lead in coal ash doesn't seem like much. Yet, after 5-10 years of organic reduction through composting and soil processes, 90-95% of the "almost pure carbon" will be gone from the source materials -- recycled into carbon dioxide and other compounds.

Therefore, composting coal ash (not pure wood charcoal ash) and using it in a garden -- effectively concentrates lead, and pollutes your soil with longlasting contaminates which are especially harmful to children.

(FWIW, I learned about this stuff while researching online after discovering people who lived in my old house many years ago had used the ash from a coal-fired furnace as landfill at the formerly-sloping far end of the backyard. I don't grow food in those areas and I don't compost the flowers or the weeds growing there either. Toxic soil levels for lead are measured in hundreds of PPM -- Parts Per Million.)

Composting with or just using plain old wood charcoal ash directly in the garden is not a problem AFAIK, as others here have said. Composting or otherwise using coal ash -- is a problem.

All the best,
-Patrick

Wow. What a lot to learn about charcoal ashes! I would love to take some of the ashes to a lab and have them analyzed. But alas, so little time. They are all white, like lime, but who knows what lurks beneath this evil facade. LOL. I'll spinkle them around the flower beds and pray. Thanks to all.

It looks like this thread has been asleep for a few months, but I was curious. Last summer I used a lot of charcoal ashes and coffee grounds and I killed and or stunted alot of plants. I think it was the ashes. I'll stay away from or rather keep them away from the garden this year.
Greg

If charcoals are so bad for a compost pile, how can they be safe to cook over?

indeed, how can we cook over them?

drtluvr, I would be thinking that the coffee grounds were the culprit rather than the ash.

I just toss my ash on the compost heap along with most everything else. No problems or difficulties to this point.

Wow! How easy it is to digress!!! For some reason, the best information posted here became about burning COAL and the byproducts of COAL ash. Coal is what is used as a heating fuel.

This forum is about using charcoal briquette ash, like what most of us use in BBQs to cook food. I see one person already freaking out about cooking with coal - haha.

As for the charcoal briquette ash, the best info is the listed ingredients of Kingsford. For what it's worth, nothing about them seems harmful (pure Carbon is not coal, and if it's pure, does not contain anything else). As per someone's post, the company does not recommend that you use the BRIQUETTES in compost, but does not seem to say anything about the ashes.

So to summarize, this has still not been answered, and I would probably be safe, rather than sorry, until proven otherwise.

And I agree about the coffee grounds. I have personally killed many plants by accident whenever my erroneous friend reminds me that it's "good fertilizer", every few years, and I forget my past experiences.

If your ashes from your bbq are NATURAL Lump charcoal with no additives - they are great for the garden as well as natural wood from your fireplace. You must make sure that NOTHING you burn is treated with any chemicals. I was raised on the farm and we always used to put the ashes from our wood stove in the garden along with coffee grounds, egg shells and anything else that was NATURAL. I would NOT use briquet ashes to cook and I certainly wouldn't put their ashes in my garden. One NOTE: If you use lighter fluid to start your bbq - you are adding chemicals to your food and fire! DON'T!

jbmaimi, we're talking about coal because it is commonly added to wood charcoal to make briquettes.

madmagic has it right - IMHO as an env. chemist it's the metals in the coal ash, as well as the borax which can be toxic to plants in sufficient quantities.

Granted, a shovelfull now and then is not going to amount to a hill of beans for a long long time.

I'm not worried about the starters and the lighter fluid. That stuff is burned off and whatever residue it does leave at those temperatures will be in the form of sooty hydrocarbons which are no different from the sooty hydrocarbons left by the charcoal!

As far as 'why is it safe too cook over if it's not safe for the garden', it's because we don't eat the ash? :-]

I rented a house with a small back yard. The property manager stated that he placed bark in the 10x10 area that was unpaved that was guaranteed to kill all manner of weeds for at least 18 months. This made it pretty much impossible to grow anything in that area, so I didn't try to plant anything whatsoever.

I enjoy barbecuing very much. I usually use Kingsford Charcoal to grill my steak, lamb, chicken, and whatever else, and I had done so for most of the two years that I lived at the unit with only a few exceptions. I placed the charcoal into a caged compost pit along with weeds plucked from the front yard and vegetable scraps among other consumer bi-products which are acceptable for such purposes as gardening.

After dumping the, alleged, toxic charcoal ash, "waste" into the compost heap, I noticed that it started to leach out into the rest of the yard. I never worried about this since I read that the ash from past volcanoes actually helped to restore the environments they once destroyed. Of course these are two different circumstances , but carbon is a major bi-product of both events.

It took around 6 months then started to notice the weeds that started to grow in the same place that was once toxic to all plant life. They grew uncontrollably in the area.

At this point I think it is fair to say that the weeds owned that yard when I moved. I attribute this fact to carbon's ability to bond to other elements; thus, cleansing our environment.

I wouldn't use Charcoal brick ash in my vegetable garden, but I think that carbon should play a role where toxins are present in the environment. Furthermore; ones ashes from a fire place should be completely safe to use in ones compost heap.

Bark mulch will not kill everything. Even if it's very deep, weed seeds can still sprout within the mulch layer. I am not sure how this area became "toxic to all plant life" unless you are speaking tongue in cheek related to the charcoal ash. I don't think charcoal ash would have that effect, except temporarily from the high pH until it leaches away.

There is not really that much carbon in either charcoal ash or volcanic ash. At least not organic carbon. There might be some carbonates but at high enough temperatures those decompose to CO2 leaving oxides. I don't think carbon had much to do with weeds thriving there.

For those who are concerned about petro products coming in contact with your veggies its a guess that you dont know that kerosine is used to ripen veggies that are picked early and sent to grocery store. just saying. but i have used charcoal ashes from grilling for years. I just toss it in the soil around my friut trees and veggies. My tomatoes are big. Not only are the fruit on them big the plants themselves get huge and they lasted through january before they died off producing fruit until then. So i see no problem with it. I also burn my shredded bills and toss those ashes in my soil. I also use coffee and fruit peels. I have suggested it to others and their gardens have done just as well as mine. I have been sickened by my garden nor has my family or friends. I am actually healthier than i had ever been.

Charcoal brickets are mostly wood waste but they are held together with binders and those that light easily have petroleum products added to make that happen. Like any other burned wood waste these charcoal brickets can have some valuable nutrients, however, the major one is Calcium Carbonate (about 21 percent) and that can have an adverse affect on your soil if not needed.
Most every soil scientist, horticulturist, and ecologist I have ever talked with about using charcoal in the garden suggests caution.
It is ethane, not kerosene, that is used to ripen fruits and vegetables.

If the charcoal is completely burned to ash (no residual unconsumed lumpy bits), then there shouldn't be any residual petroleum byproducts left behind. They would have been either volatilized from the heat or consumed long before the base material burnt to ash.

Ash is basically the inorganic stuff (think minerals) left behind after the organic stuff (think wood, etc), has been consumed. About the only form of carbon you will find in ash is as carbonate. So the real questions that people should be asking is what minerals or mineral elements were in the base material?

Pretty much all lump charcoal is just charred hardwood. But briquettes are a different matter, and vary a lot by manufacturer and specific product. Kingsford's Original (the old style stuff) has traditionally included anthracite coal, borax and limestone along with wood char and sawdust. Coal typically contains a number of heavy metals in very small amounts, but they are there. So basically with a briquette of that type beyond just wood ash you will have residuals from borax, limestone and whatever comes with the coal.

I have added charcoal ash as an additive to plants and have not killed any or seen any adverse effect but after reading this thread I wont be adding it again.

But for anyone who burns wood I have found that ash can make a big difference in the garden. Let me just say this and then you can make your own decision. My sister used to dump her wood ash in one general area in her garden. When I would go over and help her to till that garden I noticed that the soil in the dump area was easier to till and that plants in the dump area grew taller than any other part of the garden. Now I ask her to save me some of her wood ash and I use it as an additive for my plants.

I have added lots of wood ash to lawn areas to help raise the pH a bit and add nutrients back - especially P and K. Wood char I've added as a soil amendment to clay garden soil.

One thing I didn't say clearly last time around about CHARCOAL ash is that the traces of toxic metals in the ash - particularly arsenic - will build up slowly over time, since they don't degrade away. This is not an immediate toxic risk, but rather a long-term, low level exposure. Since coal is concentrated plant matter, it has a higher ash content than lump charcoal made from wood, and thus a higher metals content, which is concentrated in the ash. So that's reason #1 I do not put it on my yard. But based on what I know of the concentrations and the mass of soil in just the top 6", it would probably take years and years to see much of an effect, honestly. (I mean, to raise it to a high enough level that it exceeds health based standards for residential surface soil.)

But...Reason #2 is that borax is often used as a binder, it ends up in the ash, and elevated boron levels in soil can inhibit plant growth. It doesn't take much - as I recall, 5-10 ppm. My background B is already 1-3 ppm. :-o

#3 is the high pH as mentioned previously and this is true regardless of the type of ash. Now if you live in an area of acidic soil, it can probably absorb annual additions of ash in reasonable amounts with no ill effects. Someone with neutral or already alkaline soil should probably not be adding ashes. Or if you have high soluble calcium already.

Quilt, blanket and comforter manufacturers add a label that says "dry clean only" to avoid law suits from folks who do not know how to launder stuff. Maybe, Kingsford is adding this info just to avoid lawsuits.

There are good, valid, reasons not related to avoiding lawsuits for those labels and advising you to not use these products in waysa that could cause you harm.

kimmq is kimmsr

Lump charcoal burned in grill, ashes accumulate, put in compost, compost comes out year later, and I use my compost mostly for ornamentals and lawns, but also for gardening. The fire burns off impurities, locks new chemical bonds into the ash, the ash gets broken down (unbonded) by microbes, rebonded by rain or clay, and this cycle repeats itself. The amount of ashes cannot be much considering most people don't grill everyday and the volume of most compost piles is large, yielding (ashes to compost 1-5% to 95-99%). Then you add this changed material in compost to your garden soil at maybe 5-10%. And Voila! new reactions take place in the garden soil (different microbes & worms & clay-mineral soil structure). Remember - You and your body don't know what to do with arsenic,lead, etc and it can be toxic! But plants know what to do with these things, and tiny trace amounts of lead, cadmium, manganese, etc are good for the soil. You can actually add them if you like with Azomite! I'd consider the charcoal ashes safe, due to the fractional amount being added, and the fact that it transverses at least 5 biofilters before it gets to you.