Will sawdust that has varnish kill my garden?
November 24, 2012 1:21 PM   Subscribe

Will sawdust that has varnish kill my garden? A friend of the family asked if we wanted a large pile of sawdust he had from doing some woodwork. Sawdust makes good mulch. We wanted to accept, but some of the furniture that the sawdust had come from had been varnished and we weren't sure if that would kill our garden and/or poison the plants. Is it dangerous to use this sawdust.
posted by ArthurBarnhouse to Home & Garden (5 answers total)
Are these plants you might eat? That would make me avoid the varnished sawdust.
posted by amtho at 1:37 PM on November 24, 2012

There are different kinds of varnish - some toxic, some not. Do you know what kind of varnish was used?

Also, it might make good mulch but note that sawdust, generally speaking, is quite nitrogen deficient - as it decays it can be quite aggressive about sucking up nitrogen from its surroundings. So you'll need to provide some serious nitrogen boosts to compensate. Chicken gickem (aka poop) is the only thing I know of that has enough nitrogen to combat sawdust.

Lastly, watch out if it's pine sawdust! That's where turpentine comes from - not good for living, growing plants - especially ones you intend to eat.
posted by jammy at 1:59 PM on November 24, 2012

I'd avoid this - varnish often includes ethylbenzene or naphtha (possible carcinogens) that you don't need to deliberately add to your soil. It's also worth asking whether any of the wood used has been treated (e.g. pressure treated), as this may add flame retardants, arsenic, and other toxins.
posted by ryanshepard at 2:05 PM on November 24, 2012 [1 favorite]

Would you burn varnished wood in your fireplace?

Take care with VOCs
posted by Max Power at 2:54 PM on November 24, 2012

VOCs tend to be a problem more indoors, because when things volatilize they end up in the air (and there's a lot of air outdoors to dilute them). If you're eating the plants, I might skip it to be sure there were no problems. But if you're working with decorative plants like flowers it seems really unlikely that a small amount of old varnish would cause any growth or survival problems.
posted by ldthomps at 6:34 PM on November 24, 2012 [1 favorite]

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