Smolder and Wiser

Umbra on fireplace ashes 6

Dear Umbra,

What should we do with ashes from the fireplace? I've heard that they're great for the garden and I've heard that they may not be so good for the garden. Are they a good replacement for salt on slippery sidewalks?

Janet Allen
Syracuse, N.Y.

Dearest Janet,

Why not make some soap? Here come the holidays, after all. All you'd have to do is run water over the ashes to make potash, boil the potash down into lye, render your old cooking grease, mix it with the lye, not get any chemical burns, let it all cure for a while and then mill it into lovely gift bars. I suppose it would have been best to start saponificating in the summer, and do it all outdoors. You could save your ashes and make your own potash in the spring rains.

Get your ash out to the garden ... or not.

Photo: iStockphoto

If that doesn't appeal, then yes, you can probably put wood ash on your garden. The ashes and nutrients that were in the tree and remain after a fire are beneficial soil amendments (that means: can change the soil in a good way). As with any soil amendment, however, it's important to know what's in the stuff and whether your garden needs the particular nutrients. The chemical makeup of wood ash will depend of course on the tree that was burned, and also on how hot it burned, so there's less exactitude with wood ash than with a commercially prepared soil amendment. But it's free, and you'll be returning it to the soil whence it came.

Wood ash is an alkaline substance, a base. It is often used to lime soils, that is, to raise the pH of acid soil. Potassium is the significant available nutrient, and it is also high in salt. Because of the alkalinity, and the salt, it's not a good idea to chuck the stuff willy-nilly about the yard. You might end up over-salting the soil, choking on the ash, or disappointing/killing acid-loving plants. I've found two clear resources that give ballpark amounts to apply in the garden, and tips on how to apply the ash, one from Oklahoma Extension and the other from Oregon Extension. It's best to get a soil test, of course, so that you know the pH of your soil and whether you're low in potassium. Ash can also be added to compost piles and used very sparingly as a pest deterrent -- read all the specific instructions in these Extension publications.

As for using your ash on slippery sidewalks: I think it works, but with the major drawback of wet ash on your shoes. You alone can decide if you are willing to deal with the resultant mess.

Wishing you a warm home.

Potashly,
Umbra

 

Yours is to wonder why, hers is to answer (or try). Send your green-living questions to Umbra.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

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  1. NHsolarguy Posted 7:58 am
    12 Nov 2007

    using ashesI have a driveway that's about 1/4 mile long through the woods, which often turns into a sheet of ice. Ashes work great! As soon as they hit the ice, they melt right in (doesn't matter if they're hot or cold). I just don't put them too close to the house, so they don't get tracked in.
    Also, if you have pine trees, the ground around them will be acidic. Ashes make great fertilizer there. Or you could mulch your ashes with pine needles and/or horse manure, which is also acidic.
    Mike.

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  2. Beth Terry Posted 5:12 pm
    12 Nov 2007

    fake log ashesAnything you can do with Duraflame ash?  Nowadays it's made from non-petroleum wax, apparently.  But is there any use for it in the garden?

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  3. sallymole Posted 11:46 pm
    12 Nov 2007

    Fireplace AshesI have had great luck putting the fireplace ashes on my compost pile. They help break down the compost really quickly, and mix in well. I must say that I have not had the compost soil-tested, but I think that by the time the ash mixes with the compost and is applied to the garden, it's basic qualities are pretty well broken down.

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  4. miken32 Posted 2:54 am
    13 Nov 2007

    Hmm, fireplaces?Don't fireplaces contribute to ground level smog and release loads of nitrous oxides? Are emissions better with a wood stove as opposed to an open fireplace? And would charcoal ash from the barbecue have the same properties as wood ash from the fireplace?
    I'm thinking the answers to all 3 questions are yes, but don't know.

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  5. rachelv Posted 6:25 am
    14 Nov 2007

    ashes to ashesI agree ashes work great on icy sidewalks as long as you don't use it too close to the house. I am compost queen with a backyard pile for yard waste and a bottomless covered garage can for rotten veggies that might interest local vermin and a basement worm bin for peelings from the kitchen. Ashes would work in all but the worm bin.

    I also use ashes in my covered "chicken poop pail" for my backyard flock (okay only 4 birds but flock sounds better). The ashes kill the strong ammonia "fragrance". The pail is (of course) a re-tasked kitty litter container.

    I have a fireplace insert which burns at 70%-80% efficiency as opposed to regular fireplaces which are only -5% to 5% efficient (that's correct they actually loose heat). Because the wood is burned more completely it is supposed to dramatically reduce the air pollution over regular fireplaces (and produces very little ash compared to a regular fireplace). The insert heats our whole small house for hours with only a few pieces of wood. A wonderful and toasty investment! We scavenge free wood from our local landscape recycling center. Double bonus!

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  6. The Nourisher Posted 12:26 pm
    18 Nov 2007

    Ash water for Nixtamalizing CornNative Americans used ash water to soak corn grains  before grinding for breads. It releases vital vitamin B and proteins. Without doing so they would quickly become ill with deficiency disease pellegra.
    The Hopi obtain the necessary alkali from ashes of various native bushes or wood (typically the juniper tree) Contemporary Maya use the ashes of burnt mussels.

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