What’s the Best Wood for Raised Garden Beds?

Raised beds make gardening accessible for everyone, regardless of their location, soil type, and gardening skills. But before you can enjoy the benefits of raised beds, you have to determine which type of bed you’d like to add to your garden. Not only do you have to decide whether you’d like to purchase a premade bed or build a custom garden bed, but you also have to figure out what material fits your goals and budget.

Many gardeners find wood garden beds attractive. They seamlessly fit into natural landscapes and can be customized to just the right size. But before you head to your hardware store and grab the cheapest lumber you can find, know that not all wood is created equal!

Choosing the proper type of wood can make the difference between beds that last ten years and those that rot away after a few growing seasons. Join me to learn five types of wood that work well for raised beds.

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• come in 3 convenient sizes
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The Short Answer

The best wood for raised beds is untreated and naturally rot-resistant. Some types of wood that work well include cedar, redwood, cypress, black locust, and osage orange. These materials last for multiple years without leaching harmful chemicals into the soil.

The Long Answer

Knowing the best type of wood for your raised beds is great, but understanding what makes these types of wood good options is even better. I’ll cover what factors make wood desirable, then cover some of the best types of wood for long-lasting garden beds.

What to Look for When Selecting Wood

Building a wooden raised bed can be expensive. I understand the appeal of grabbing some scrap wood or free pallets to save money. Think about the type of wood and how it was treated before your purchase.

Treated vs. Untreated Wood

While treated wood lasts longer than untreated wood of the same variety, the chemicals used to protect the lumber from fungi and insects may have a negative impact on the environment. The preservatives used to treat wood have changed over time; while manufacturers often used chromated copper arsenate (CCA) to treat residential lumber, this stopped in 2003.

People use numerous materials to treat wood intended for residential use, but alkaline copper quaternary (ACQ) and copper azole (CA) are some of the most commonly used chemicals. The main danger of these substances lies in the high concentration of copper. Although copper is naturally found in the environment, it is toxic in high quantities, especially to children.

With that said, one study reported that regular contact with the boards wouldn’t lead children to become exposed to adverse levels of copper. However, you ultimately have to ask yourself what level of risk you’re comfortable with.

Hardwood vs. Softwood

Hardwoods are deciduous trees like maples, oaks, and locusts, while softwoods are conifers like pines and cedars. There’s no rule saying that hardwoods are better than softwoods or vice versa, but there are some notable differences between the two.

Since hardwoods typically grow slower than softwoods, their lumber is often more expensive. Hardwoods are also more durable than softwoods, but they’re also heavier. While you can use both hardwoods and softwoods for raised garden beds, softwoods are often a better option due to their lower price and lighter weight.

Best Types of Wood

So, what type of wood should you look for when building or purchasing raised beds? If you’d like to avoid treated wood, give these naturally rot-resistant options a try.

Cedar

Although many people use the term cedar like it’s a single plant, multiple species and genera of plants are considered cedars! In the United States, the three most common cedar species are the eastern red cedar (Juniperus virginiana), western red cedar (Thuja plicata), and yellow cedar (Callitropsis nootkatensis). While these species vary in their native range and appearance, they’re all highly resistant to decay and great options for your garden.

One study testing the durability of various tree species found that all three cedar species held up well after five years. Much of this durability is due to the presence of naturally occurring extractives like thujaplicin and plicatic acid, which protect the tree from fungal decay. Since these extractives vary between trees and throughout individual trees, you may find that one cedar board rots faster than another. However, you can expect most untreated cedar to last at least ten years before it starts to decay!

Not only are cedar boards resistant to decay, but they’re also beautiful and fragrant. The boards and mulch emit an unmistakably pine-like fragrance with hints of citrus. And since cedar is relatively lightweight, it’s easy to move and assemble.

Cypress

Native to bogs, swamps, and riverbanks, cypress trees are prized trees in the southern and southeastern United States. The common bald cypress (Taxodium distichum) thrives in silty areas near ponds and rivers throughout much of the East Coast and South. The pond cypress (Taxodium ascendens) grows in slow-moving blackwater rivers and swamps in the southeast US.

Like cedars, cypress trees are naturally resistant to fungal rot and termites. The molecule responsible for this natural resistance is known as cypressene. Since older cypress trees have accumulated more cypressene than younger trees, they’re more rot-resistant and the top choice for raised beds and other applications. However, continued timbering of old-growth forests makes it difficult to find mature trees.

If you live in the southeast United States, you may still be able to find suitable cedar boards for garden beds. Old-growth wood can easily last over a decade, making it an excellent choice for a long-lasting raised bed.

Redwood

When you think of redwood trees, you probably imagine massive trees towering overhead. But these trees also produce a strong wood that’s resistant to rot, insects, and fire damage. Therefore, redwood is an excellent option.

If you opt to use redwood, make sure to look for boards made from old-growth trees. These mature trees are more rot resistant than younger trees, so they’ll lead to longer-lasting raised beds.

Although redwood lumber is more expensive than pine, it’s comparable with other types of rot-resistant wood. It’s often more affordable if you live on the West Coast where redwoods grow.

Black Locust

Most people think of softwoods like cedar and cypress when they imagine rot-resistant timber, but the hardwood black locust (Robinia pseudoacacia) is another excellent choice for outdoor raised beds. This tree grows much more quickly than other hardwoods and possesses excellent rot resistance due to the presence of robinin. That’s why people have used it for years as fence and deck posts.

If you’re milling your own lumber or picking out boards from a lumber yard, keep in mind that only the heartwood of black locust is rot-resistant. The sapwood found near the outside of the tree doesn’t have the same desirable qualities and will rot much quicker.

Black locust wood is heavy, making it more difficult to handle than other types of rot-resistant wood. However, its heaviness correlates with sturdiness and strength.

People sometimes confuse black locust with the honey locust. The latter is in a different genus and lacks the rot resistance of the former. Therefore, make sure you’re using black locust wood and not honey locust wood.

Osage Orange

Also known as the hedgeapple, the osage orange (Maclura pomifera) is a deciduous tree native to much of the south and central United States. The tree isn’t a true orange but produces knobby, green fruits the size of a softball. It’s also known for fast growth and hard, rot-resistant wood.

Although the wood is excellent for raised beds, you may find it difficult to locate long boards. Due to the tree’s fast-growing nature, people often plant a row of trees close together to form a living hedge, leading to trunks that are less than two feet wide. The trees often develop a twisty shape, making it difficult to cut straight boards. So if you find long, straight boards, grab them!

Osage orange wood has a stunning light color that ranges from gold to light orange. Just remember that the hard wood may be difficult to cut at home!