Raised beds are a great solution for gardeners with shallow soils, but they don’t come cheap. Cedar is expensive, and many of the store-bought solutions will set you back $100 or more per bed. A raised bed doesn’t need to be made from finished lumber, and making raised beds from raw logs harvested on your own land is the perfect inexpensive raised bed solution.
Beyond saving money, log raised beds also work with the natural soil ecosystem to help buffer moisture levels and promote natural fungal activity in the soil.
Why Build Log Raised Beds?
Vermont gets a good bit of rain in the summer, and often all in big bursts. In the past 48 hours, we’ve had just over 4 inches of rain, beating the monthly average for June in just two days. Rain bursts like that wreak havoc on our shallow soils. Our land has 10-18 inches of topsoil on top of impermeable clay, which means low spots in the soil become ponds and anywhere with a slope washes out in large rain events.
What does this mean for our garden?
Anything that’s not raised in some way sits in standing water for at least a few days each month.
The solution? Raised beds!
In the past few years, just as our garden is trying to get going in early June, we’ve had rain nearly every single day. Last year that left our garden with 1-2 inches of standing water for the entire month. The only thing that can live with that kind of treatment is tomatillos because you just can’t kill those things. (Seriously, we harvested tomatillos with a rake one year from a waist-high hay field where they had grown in from seed and made 12 quarts of green sauce. Indestructible!)
Given our shallow soils and heavy rain events, we decided the best option would be to convert our annual garden to a no-till raised bed system. The problem is, cedar boards for raised beds are very expensive. Cinder blocks are also expensive, and perhaps a bit too permanent. Pressure treated wood lasts, but is toxic.
Given that, it seemed best to use something that is free, but would rot eventually. Softwood logs, specifically hemlock, are abundant on our land. We need to cut them anyway just to get enough sunlight to be able to plant a garden (though we also plant many vegetables that grow in shade in low light areas).
A new log raised bed in our garden is already helping to buffer heavy rain events in the garden just a few days after planting tomato seedlings. The area around the bed had standing water for over a week, but the tomatoes thrived in their new bed.
How Long Do Log Raised Beds Last?
Our initial thought was that log raised beds would last at least 5-7 years, and after they’ve rotted away, they’ll improve our soil with organic matter and can easily be replaced with more hemlock. The beds we built for perennials 6 years ago are still going strong, and now I have no doubt they’ll make it 10-12 years at this rate.
That’s with using softwoods known to break down rapidly. I imagine they’d do better with slow rotting wood types, but those are better saved for fence posts or firewood.
Hemlock has very low BTU’s when burned, roughly half that of hardwood, and due to creosote buildup issues, it can only be burned in external boilers (not in wood stoves). Pine and other softwoods have the same issues. Thus if you need to cut softwood for other reasons, one of the best uses for it is as a raised bed (unless you have your own portable sawmill).
How to Build Log Raised Beds
Next, place your logs in the trench. Leave them as big as you can reasonably carry. If you can find dead wood already downed even better. The mycological community in the wood will help to improve your soil even more.
How to Plant Log Raised Beds
Bark sheets as mulch, covered by leaves on a path between two long log raised beds of strawberry plants.
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Marcia Emery
What about the grubs I see under the bark of drying trees?
Ashley Adamant
If there are grubs in a dying tree, that’s what they’re eating (not your veggies). They’ll likely keep eating it, helping it decompose and releasing nutrients into the soil. I wouldn’t worry about bugs in the tree harming your crops (unless you’re growing trees in the raised beds…)