5 Rot-Resistant Woods For Building Raised Garden Beds

Pressure-treated lumber can leach metals into the soil. When building raised garden beds, use one of these five naturally rot-resistant woods instead.

by J. Keeler Johnson
PHOTO: Raised garden beds

Picture the scene: a lovely garden filled with tidy raised beds, each containing a different type of vegetable, herb, flower, etc. Grass and stone pavers line the paths between the beds.

It’s picturesque and beautiful.

But wait … are those beds made with pressure-treated lumber? You might assume the answer is yes, since pressure-treated lumber is more resistant to rot and decay than untreated lumber. This makes it suitable for outdoor construction.

However, treated lumber isn’t completely immune to rot. And over time the materials used to pressure-treat lumber (arsenic, copper, etc.) can leach into the soil and wind up in the food chain. Plant roots are often where these metals become concentrated, so root vegetables like potatoes and carrots are obviously susceptible to leaching.

But even the leaves of plants like lettuce and spinach can be affected.

The good news is, you don’t have to build your garden beds out of pressure-treated lumber. There are many types of wood that are naturally resistant to rot, moisture, and/or insects, making them durable and suitable for use in gardens.

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If you’re looking to steer clear of using treated lumber for your raised garden beds, we have you covered. The following five woods are naturally long-lasting and ideal for building raised garden beds:

1. Cedar

Cedar is widely used in outdoor construction. If you want to shingle your roof in wood, cedar shingles are a fine choice.

In addition to being durable, cedar wood has a lovely appearance and a pleasant aroma. So cedar furniture is a good way to appreciate its qualities. And yes, you can build or buy raised garden beds made from cedar wood.

Read more: Small farms hold a wealth of treasure in on-site woodlots!

2. Osage Orange

The wood of the Osage Orange tree is incredibly hard and therefore durable when used outdoors.

Janka ratings measure the hardness of different wood types. Whereas well-known hardwoods like oaks and maples fall in the 1,200-1,500 range, Osage Orange is up in the 2,000s. Driving nails into Osage Orange wood isn’t easy, but if you’re looking for a tough wood for building raised garden beds, you’ve found it.

3. Black Locust

Black Locust wood has long been valued for fence posts and railway ties because it can resist rotting for decades. Like Osage Orange, it’s very hard wood (harder than maple and oak) well-suited to building raised garden beds.

Read more: Ready to build a raised bed? Here’s how.

4. Redwood

Redwood is yet another quality wood resistant to rot and insect pests. In addition, it’s lovely in appearance with attractive grain, adding a decorative touch to your garden.

If possible, shop for lumber made from the heartwood. This performs better than the sapwood.

5. Teak

Teak isn’t native to North America. It actually grows in the southern and southeastern regions of Asia. But its oily wood is strong and resistant to rot and insects, making it popular for a wide variety of outdoor construction projects.

Of course, these aren’t the only types of wood suitable for building untreated raised garden beds. If you don’t mind replacing the beds on a semi-regular basis, even wood that decays after a few years can be used.

But if you opt to build garden beds from one of these five hardy woods, you’ll be investing in long-lasting lumber without any need to worry about chemical treatments. That sounds like a win-win result!

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