It may seem like spring planting is a long way off, but if you’ve been thinking about trying a raised bed kit this year, now is a great time to determine which type will work best for you.
Why might you want a raised garden bed? They offer many advantages. Raised beds keep grass paths from spreading into planting beds, prevent soil compaction from stray footsteps, improve drainage, prevent erosion, and can extend the growing season. Filling raised beds with quality soil is also cheaper and less backbreaking than amending your entire garden to improve soil texture.
As DIY carpentry goes, building raised beds is a fairly simple project, but if you’re not particularly handy, it can still be intimidating. Fortunately, there are many kits that make installing raised beds easy for even the clumsiest of green thumbs. Which raised bed kit is the best for your garden and the planet?
First of all, raised beds are not the same as planters. Unlike containers, raised beds are open on the bottom, allowing roots to extend into the ground. The best raised bed for your garden depends on several factors, including aesthetics, ergonomics, and construction material. The material used for a raised bed can affect aesthetics and ergonomics, and it’s the biggest factor in environmental impact. Raised beds are most commonly made of natural wood, composite, plastic, or metal. Each of these materials has costs and benefits, and there may not be a clear-cut environmental winner for all circumstances.
Although they may be made from recycled plastic and are technically recyclable, we will not evaluate raised beds made of HDPE, because so few communities are able to recycle plastic in practice and because of the role plastics play in ocean pollution.
Naturally rot-resistant woods like cedar and black locust are the best woods to use for garden beds. Redwood is an excellent choice if you can find a sustainable source. Since the EPA banned the sale of wood treated with chromated copper arsenate (CCA) for residential use, alkaline copper quat (ACQ) and copper azole (CA-B) have become the standard treatment. However, organic standards preclude pressure-treated wood of any kind.
Oregon-based Naturalyards cedar raised beds are held together by rust-free aluminum pins and crossbars, requiring no tools for assembly. The SFI-certified wood is saturated with a nontoxic sealant that protects the boards from rot. It does not include UV protectors, so the cedar will fade naturally to silver-gray. Naturalyards raised beds come in rectangular, hexagonal, octagonal, and L- and U-shapes, with optional trim, trellising, and custom sizing.
- Greenes Fence Company – Cedar
Based in Ohio with manufacturing and distribution centers throughout the U.S., Greenes Fence Company makes untreated cedar raised beds assembled by sliding planks into grooves in the posts. Among the least expensive raised bed kits, their simple modular design allows for stacking or combining into more complicated L or U shapes.
- Gardener’s Supply Company – Cedar
Gardener’s Supply Company’s 15-inch deep cedar beds are made with SFI-certified, untreated Western red cedar planks screwed to aluminum corners with plastic caps. All are three feet wide and available in several lengths.
Most composite is a blend of wood fiber and UV-protected, recycled polypropylene. Because composites are made from waste materials and do not rot, they have been hailed as a sustainable alternative to natural wood. However, because they are made from two different waste materials that cannot be separated, wood/plastic composite lumber is not recyclable.
- Gardener’s Supply Company – Sienna Composite
Textured to resemble wood, Gardener’s Supply Company’s composite boards are made from 38% post-consumer recycled plastic and 62% sustainable hardwood fibers, with corner brackets made from ABS plastic resin. Although made from recycled materials and expected to last decades, you can’t recycle composite boards.
- Durable GreenBed
This Oregon-based company makes raised bed kits out of Faswall, a unique woodchip/Portland cement composite with at least 60% recycled content. All-natural, biodegradable, and nontoxic, these beds are available in several different sizes and configurations, including tiers, rectangles, and L shapes. They are tall enough to sit on. A potential bonus is that the rough texture of the walls may deter slugs.
Galvanized steel is recyclable and rust-resistant, lasting from 30 to 70 years. However, the galvanized coating contains zinc and chromium, which may leach into soil over time. These essential micronutrients are toxic in higher amounts. Galvanized containers are generally recognized as safe because high levels of zinc or chromium would kill plants before they could grow to be eaten; however, a definitive answer to the question of whether galvanized steel is appropriate for food crops is not available.
- Greenes Fence Company – Metal
Available in only one size, this bed assembles without tools by sliding together with a keyhole locking mechanism. Made from pre-galvanized powder-coated steel and available in four different colors.
- Gardener’s Supply Company – Modular
With nine possible configurations, this Australia-made galvanized steel, Aluzinc-coated raised bed offers a 15-inch planting depth. The clip-on PVC strip on top of the rolled edges is not sustainable but improves safety. The Aluzinc powder coating is supposed to extend the planter’s life up to six times longer than regular galvanized steel.
To download our printable comparison chart, click the image below.
Originally published on January 7, 2019, this article was updated in January 2022.