Garden boxes are awesome. They can also be expensive. Last year I spent hours evaluating lumber options for our garden boxes. Pressure treated was, of course, out. Cedar was a good bet. Also redwood. However, those came at a cost of nearly three times as good old douglas fir boards.
In the end, we went with doug fir. It cost under $100, and we figured that even in our humid location here in the Pacific Northwest we should get maybe five years use out of them, and replacing them was still less expensive than using the more expensive lumber.
But I really, really hate redoing my work.
Then just today it hit me. The most beautiful, genius plan ever. I was in the middle of burning a project when this bit of inspiration came. Wood burning, or sho sugi ban, it is an ancient Japanese form of wood preservation. Charring the wood renders it weather resistant, bug resistant, and believe it or not, even fire resistant.
It’s also quite fun.
By charring the garden boxes we should get maybe up to 80 years of use out of our boards instead of 5. Admittedly, that may be a high estimate, because our boards were burned after the garden has been in place for a year and are, obviously, full of dirt.
Burning your garden boxes
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I cannot recommend this method for existing gardens, simply because it is not very safe to burn in place, and because it is not possible to get down past the dirt. That said, that is exactly what I did. We live in a place the Japanese once failed to burn to the ground simply because winters are so darn wet here. (Really.) The garden was surrounded by a thick coat of algae when I burned the boxes. Still, I don’t recommend it because it would make me really sad to hear someone burned their home to the ground. So, just to restate, this is a what we did rather than a you should do.
I do most of my wood burning projects on the driveway with a water hose right on hand. It’s good practice. You’ll find it is surprisingly difficult to actually start the wood burning, but there’s nothing to be lost by caution.
We use a torch attached to a propane tank. We picked it up for $30 at Harbor Freight. I believe it is the same as this one on Amazon. The idea is to burn the wood until you get a good, deep char – until it develops the look of alligator skin.
That’s really it. You can brush it down to knock off the soot. I did not bother with a finish on mine. Finishing with a natural oil looks great, but, well, that’s a lot of oil.
Here’s how those boxes look now. It’s February, so the garden isn’t so pretty as it was in that first photo. Come spring it will be bursting with greens and looking like a million bucks. Which is great, because it cost a whole lot less.
Seriously, everything is still looking very…winter around here. It’s been raining for days and I went and grabbed these photos the moment it cleared. That’s not burn marks on the fence, it’s mud splatter from the power washing we started on our algae covered patio.
Is it Spring yet?!
Follow along for the next few decades and I’ll let you know how these boxes are holding up!