Choose the Best Wood for Building Raised Garden Beds
Raised garden beds enable gardeners to grow vegetables, herbs, flowers, and other plants in structured boxes placed atop soil. The confinement allows for proper drainage and depth for healthy root systems. It also helps concentrate compost and nutrients while protecting plants from pests.
When it comes to building a raised bed, few considerations are as important as selecting suitable wood. The right wood provides adequate strength and greatly influences longevity before needing repair or reconstruction. Therefore, properly weighing various types of woods merits careful attention.
Main Wood Type Options
Pine
Pine offers an very affordable and readily availabile wood for raised beds. Since it costs less than cedar and redwood, it is popular choice among home gardeners, especially those building their first raised beds. Pine's softness also makes it relatively easy to work with using basic tools.
In terms of durability, untreated pine usually survives between 5-7 years before beginning to rot. Opting for pine certified by the Forest Stewardship Council (FSC) gives reassurance the wood was responsibly sourced. Most importantly, using untreated pine avoids exposure to the toxins found in pressure-treated lumber.
Cedar
Western red cedar deserves its popularity among raised bed builders. Available in planks, boards, and timbers, it combines visual appeal with natural resistance to moisture, decay, and insect damage. Containing oils that act as preservatives, high-quality cedar can endure for 15 years or longer. This makes it a common choice for vegetable gardens.
Eastern white cedar, while not as decay-resistant as its western counterpart, shares an attractive appearance and provides reasonable durability. Just be sure to use heartwood (the innermost part of the tree) rather than sapwood cuts to enhance longevity.
Redwood
In regions where it thrives, coast redwood makes an exceptional wood for raised beds. Redwood contains tannins and oils giving it natural resistance to moisture, rot, and insects. With proper care, it can last over 20 years without replacement. Redwood also weathers to a beautiful silver-gray over time.
That said, redwood costs more than pine or cedar--especially for pieces thick enough for sturdy raised beds. And despite its strengths, it may develop small surface cracks over years of exposure.
Other Durable & Eco-Friendly Options
While pine, cedar, and redwood constitute the most popular woods for raised beds, other types bring unique strengths.
Cypress
Bald cypress thrives in hot, humid climates and makes an excellent wood for raised beds where decay poses problems. Even partially buried in soil, cypress demonstrates strong rot and insect resistance. Its fine, interwoven grain gives balustrades and borders a handsome aesthetic. Just note that cypress is heavier than softwoods like pine and cedar.
Hemlock
Occurring throughout North America, hemlock offers natural rot-resistance, strength, and beauty. With care, it endures exposure well for 5+ years before replacement becomes necessary. As an added plus, hemlock demonstrates natural insect-repelling properties.
Teak
In tropical environments, teak reigns supreme as an enduring hardwood. Containing oils that help it stand up to weather, bugs, and fungal decay, teak can easily last 30+ years as a raised bed. And it looks beautiful as it ages. Just expect to pay a premium price for this premium wood.
Alternatives to Wood
While various woods have clear strengths for raised garden beds, some alternatives merit consideration:
Galvanized Steel
For a modern, no-rot option, galvanized steel makes an intriguing choice. Powder-coated steel withstands weathering and provides a cleaner, more uniform appearance than wood over time. Steel raised beds also tend to cost less while allowing for simple reconfiguration.
Concrete
Concrete yields strong, level, long-lasting raised beds. They hold up extremely well to exposure and provide excellent drainage. You can even cast attractive designs or textures using concrete. Just keep in mind that concrete tends to crack over time and can leach lime into very acidic soils.
Plastic Lumber
For a lightweight and portable option, plastic lumber offers intriguing benefits. Recycled plastic beds eliminate concerns of splintering and decay. They also avoid wood preservative leaching. Just make sure UV-protection exists to prevent sun damage.
Key Considerations
Beyond choosing a type of wood or material, several other factors influence raised bed options:
Treated vs. Untreated Wood
Conventional wisdom suggests avoiding treated woods for raised veggie gardens. Substances like copper chromium arsenate (CCA) or copper azole can leach into soils. Opt for untreated cedar, redwood, cypress or use preservatives specifically approved for garden use instead.
Heartwood vs. Sapwood
For naturally rot-resistant woods like cedar and redwood, heartwood outperforms sapwood. Cut from the innermost part of the tree, heartwood contains aging compounds that boost decay resistance. Sapwood cuts taken from outer tree layers remain more porous and prone to rot.
Ensuring Proper Drainage
No matter what wood gets used, ensuring adequate drainage prevents premature bed failure. Line bottoms with hardware cloth to prevent rodent issues. Adding layers of gravel or stones also aids drainage while reducing capillary action of moisture.
Matching Wood to Climate
Building a raised bed with pine in the cool, arid mountain West proves far different than using it in muggy Mississippi. Factor in humidity, average rainfall and other climate considerations. Teak and cedar fair better in soaked environments than dry regions for instance.
When it comes to the best wood for raised garden beds, pine, cedar and redwood stand atop the rest. Yet don't automatically rule out plentiful native species either. Just be sure to use untreated, rot-resistant woods to enable the longest usefulness before bed reconstruction becomes necessary. This allows home gardeners to enjoy planting and harvesting bounty for many seasons to come.