Cedar and redwood last longest, but pressure-treated lumber costs less and works fine for vegetables

The best wood for a raised bed depends on how long you want it to last and how much you want to spend. Cedar and redwood resist rot naturally and can last 10 to 15 years without treatment. Pressure-treated lumber costs roughly half as much, lasts 15 to 20 years, and is safe for growing food — the arsenic used in older treatments was phased out in 2004. Untreated pine and fir rot within 3 to 5 years. For most gardeners, pressure-treated 2-by-10 or 2-by-12 boards are the practical choice: they're affordable, durable enough to outlast several crop cycles, and widely available at any hardware store.

The wood you choose affects both your upfront cost and how often you'll rebuild. A 4-by-8-foot bed made from cedar costs roughly $150 to $200 in materials; the same bed in pressure-treated lumber runs $60 to $90. If you're building multiple beds or working with a tight budget, pressure-treated makes sense. If you plan to keep the same bed for 15 years and prefer to avoid any chemical treatment, cedar is worth the premium.

Key Takeaways

  • Pressure-treated lumber is safe for vegetable gardens, lasts 15 to 20 years, and costs half what cedar does.
  • Cedar and redwood resist rot naturally and last 10 to 15 years, but cost significantly more per board.
  • Untreated pine and fir are cheap but rot within 3 to 5 years and will need replacement sooner than treated wood.
  • Board thickness matters: 2-by-10 or 2-by-12 boards are standard for raised beds and provide enough depth for most vegetables.
  • Avoid railroad ties and old treated lumber containing arsenic, which was banned for residential use in 2004.

Pressure-treated lumber: the practical middle ground

Pressure-treated wood is lumber infused with copper-based preservatives under pressure, which forces the chemical deep into the wood fibers. Modern pressure-treated lumber has been safe for food gardens since 2004, when the EPA banned chromated copper arsenate (CCA) — the arsenic-based treatment used before that year. Current treatments use copper compounds that don't leach into soil at levels that harm plants or people. The wood is still wood; the treatment just slows decay.

A 2-by-10 pressure-treated board typically costs $8 to $15 per 8-foot length, depending on your region and the retailer. For a standard 4-by-8-foot bed, you'll need two 8-foot boards and two 4-foot boards (cut from an 8-foot board), totaling roughly $40 to $60 in lumber alone. The wood arrives ready to use — no staining, sealing, or waiting required. It will gray over time as the surface weathers, but the structural integrity remains intact for 15 to 20 years.

The main drawback is appearance. Pressure-treated wood has a greenish or yellowish tint when new, which some gardeners find unattractive. It also contains more moisture than untreated wood, so boards may warp slightly during the first season as they dry. Fastening the corners with galvanized or stainless steel bolts (not nails) prevents the wood from pulling apart as it settles.

Cedar and redwood: natural rot resistance at higher cost

Cedar and redwood contain natural oils and compounds that resist decay and insect damage without chemical treatment. These woods are genuinely durable — a cedar bed can last 10 to 15 years with minimal maintenance. They also look better than pressure-treated wood: cedar has a warm, reddish tone that weathers to a silvery gray, and redwood is similar. Many gardeners prefer the appearance enough to justify the cost.

A 2-by-10 cedar board costs $20 to $35 per 8-foot length, roughly double the price of pressure-treated. Redwood is similar or slightly more expensive depending on availability in your region. For the same 4-by-8-foot bed, cedar materials run $80 to $140. Cedar is also lighter and easier to handle than pressure-treated wood, which matters if you're building alone or moving the bed after assembly.

Cedar does require more maintenance than pressure-treated wood. The natural oils that protect it fade over time, especially in direct sun and rain. Many gardeners explore a clear sealant every 2 to 3 years to extend the life and preserve the color. Without sealing, cedar will still last 10 years, but it grays faster and may develop surface cracks. If you skip maintenance, you're not saving money — you're just accepting a shorter lifespan.

Untreated pine and fir: cheap but short-lived

Untreated pine and fir are the cheapest options, costing $4 to $8 per 2-by-10 board. They're straightforward to find and work with, and they look fine when new. The problem is durability: untreated softwoods rot within 3 to 5 years when in contact with soil and moisture. You'll be rebuilding the bed before most gardeners would rebuild a pressure-treated one.

Untreated wood makes sense only if you're testing a raised bed for the first time and want to spend as little as possible upfront. If you plan to keep the bed for more than one season, the cost per year of use is actually higher than pressure-treated lumber. You're also more likely to have boards fail mid-season, which means draining soil, replacing boards, and replanting — a hassle that costs time and money.

Composite and recycled plastic boards: low maintenance, high upfront cost

Composite boards made from wood fibers and plastic don't rot, don't need sealing, and last 25 years or more. They cost $30 to $50 per 8-foot board, making a 4-by-8-foot bed roughly $200 to $300 in materials. They're heavier than wood, which makes assembly harder but also means they won't warp or shift over time. They also don't splinter, which matters if you have children or pets around the bed.

The trade-off is appearance and feel. Composite boards look synthetic and don't age the way wood does. They also absorb and hold heat more than wood, which can warm the soil faster in spring but may dry it out faster in summer. Some gardeners dislike the plastic-like texture and prefer the look of real wood, even if it requires more maintenance.

Wood to avoid and why

Do not use railroad ties, creosote-treated utility poles, or any wood treated before 2004. Railroad ties are soaked in creosote, a coal tar derivative that is toxic to plants and people and leaches into soil over time. Utility poles are often treated with pentachlorophenol (PCP), another toxic preservative. Older pressure-treated wood (pre-2004) contains arsenic, which accumulates in soil and is especially dangerous for children who play in or around the bed.

Avoid wood from demolition sites or unknown sources unless you're certain of its treatment history. Painted or stained wood may contain lead or other harmful compounds. Treated plywood is not suitable for raised beds because the glues break down when wet, and the plies separate. Stick to solid boards, not engineered wood products.

Choosing the right thickness and grade

Raised bed boards are typically 2 inches thick (actual dimension: 1.5 inches) and 8 to 12 inches tall. A 2-by-10 board gives you 9.5 inches of depth, which is enough for most vegetables — lettuce, spinach, and herbs need 6 inches; tomatoes, peppers, and carrots need 8 to 10 inches; potatoes and root crops need 10 to 12 inches. A 2-by-12 gives you 11.5 inches and costs only slightly more, so it's a good choice if you plan to grow deep-rooted plants.

Grade matters less for raised beds than for structural lumber. Standard or utility grade is fine — you don't need select or premium grade. Pressure-treated lumber is graded the same way as untreated wood, so a standard 2-by-10 is a standard 2-by-10 regardless of treatment. Buy from a lumber yard or big-box hardware store where you can inspect the boards for obvious warping or damage before purchase.

Fastening and assembly tips

Use galvanized or stainless steel bolts, screws, or nails — never plain steel, which rusts quickly in wet soil. Galvanized fasteners cost a few dollars more but last as long as the wood. Stainless steel is more expensive but won't stain the wood or corrode. Avoid wood screws designed for drywall; use exterior-grade deck screws or bolts rated for outdoor use.

Assemble the bed on level ground and check the corners with a square before tightening fasteners fully. Pressure-treated wood shrinks as it dries, so tighten bolts again after the first month. Cedar and redwood shrink less, but checking after a few weeks is still a good idea. If you're stacking boards to make a deeper bed, bolt or screw the layers together so they don't shift when you fill it with soil.

Frequently Asked Questions

Is pressure-treated wood safe for growing vegetables?

Yes. Modern pressure-treated lumber (post-2004) uses copper-based preservatives that are safe for food gardens. The arsenic-based treatment (CCA) was banned in 2004. Copper doesn't leach into soil at harmful levels, and studies show no measurable contamination in vegetables grown in pressure-treated beds. If your bed was built before 2004, replace it.

How deep does a raised bed need to be?

Most vegetables need 8 to 10 inches of soil depth. Shallow-rooted plants like lettuce and herbs do fine in 6 inches. Deep-rooted plants like carrots, potatoes, and tomatoes need 10 to 12 inches. A 2-by-10 board (9.5 inches deep) works for most gardens; a 2-by-12 (11.5 inches) is better if you grow a lot of root crops.

Can I use plywood for a raised bed?

No. Plywood is made from thin layers glued together, and the glue breaks down when exposed to constant moisture. The plies separate within a year or two, and the bed falls apart. Use solid boards instead — 2-by-10 or 2-by-12 lumber is the standard choice.

How long will a cedar bed actually last?

Cedar typically lasts 10 to 15 years. The lifespan depends on climate, maintenance, and how much sun and rain the bed gets. In dry climates, cedar lasts longer. In wet climates or full sun, it may need sealing every 2 to 3 years to reach 15 years. Without sealing, expect 8 to 10 years.

Should I line the bottom of the bed with landscape fabric?

Landscape fabric is optional. It slows weed growth from below but also slows drainage and can trap water against the wood, speeding decay. Many gardeners skip it and straightforward pull weeds that grow up through the bottom. If you use fabric, use a permeable type rated for drainage, not a moisture barrier.