Wooden vs metal raised beds: practical differences

Illustration of vegetable raised beds with clear access paths

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Choosing between a wooden and a metal raised bed is rarely about which material is universally better. It is about how each behaves in your garden, how long you expect it to last, and how much maintenance you are willing to take on. Compare the frame construction, dimensions, repair options and total cost for your own site. Neither material removes the need for stable support, suitable soil depth and drainage.

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What the RHS says about timber raised beds

Timber is the most popular material for raised beds and is very versatile. Pressure-treated softwood sleepers are described by the RHS as an attractive and economical alternative to hardwoods like oak, and they will last for many years. Untreated wood, such as recycled pallets or scaffold boards, has a shorter life. Light untreated boards may deteriorate quickly, but lifespan varies with timber species, thickness, soil contact and local conditions; one or two years is not a universal limit. If using a preservative, choose one explicitly suitable for the intended raised-bed use and follow its label. A side lining can separate timber and soil, but cannot make unsuitable or contaminated timber safe; leave drainage unobstructed.

Ready-made timber kits are popular for beginners because they can simply be screwed together and placed in the desired spot. The RHS also notes that saprotrophic fungi can colonise and rot down untreated timber, softening it over time. If you are struggling to control honey fungus in your garden, the RHS suggests steering clear of timber and choosing masonry or recycled plastic instead, because the wood may act as an additional food source for the fungus.

Metal raised bed construction

Compare the metal, coating, panel thickness, edge finishing and bracing of individual kits. Metal avoids timber rot, but corrosion and damaged coatings can affect longevity. Follow the maker’s instructions for fixings, repairs and use on hard surfaces.

Direct practical differences

Durability and maintenance

Timber requires ongoing attention. Untreated boards may need preservative treatment and eventual replacement within a few years. Pressure-treated softwood lasts longer, but the RHS does not give a specific number of years. Metal beds generally need less routine maintenance because they do not rot, but you should inspect the coating regularly and touch up any damage to prevent rust. There is no universal lifespan for metal beds; it depends on the material thickness and coating system.

Soil temperature

Metal conducts heat more readily than timber, so exposed panel surfaces and nearby soil can warm quickly in sun. That does not establish that an entire metal bed will be hotter or give earlier crops. Colour, bed size, soil volume, moisture and shade all matter. For a small exposed bed, plan watering and check conditions near the sunny edge.

Drainage

Both materials need adequate drainage, especially if the bed is built on a hard surface. The RHS advises drilling plenty of holes in the sides of a timber bed on a hard surface. For a metal bed, check whether drainage holes are pre-drilled. If not, you may need to drill them yourself, but only if the manufacturer allows modification; protect cut edges as instructed. Use the chosen kit’s hard-surface installation instructions.

Assembly and weight

Timber kits are usually screwed together with coach screws, and the RHS step-by-step guide describes overlapping joints and vertical battens for taller beds. Metal kits often use bolts, clips or interlocking panels. The assembly method varies by manufacturer, so follow the model-specific instructions. In terms of weight, a metal panel is often lighter than an equivalent thick timber sleeper, but the overall bed weight depends on dimensions and material thickness. Do not assume one is always easier to move.

Safety and edges

Timber can splinter, especially if untreated or weathered. Metal panels can have sharp cut edges or corners, particularly on budget kits. Check the manufacturer’s edge finishing and consider wearing gloves during assembly. Inspect edges, corner caps and fixings before filling and during later maintenance.

Cost

Obtain current delivered prices for comparable internal sizes and depths. Metal raised bed kits vary widely in price depending on material, thickness and coating. There is no reliable general rule that one is cheaper than the other. Compare the total cost including any required lining, preservative or additional fixings.

Deciding factors checklist

Site drainage: If your garden soil is waterlogged, a raised bed helps, but the frame material does not change the need for drainage holes on hard surfaces.
What you grow: The RHS depth guidance applies regardless of material: 30cm is enough for dwarf bulbs, salad leaves and strawberries, while most fruit bushes, shrubs and small trees need 45cm or more.
Accessibility: Both materials can be built to a comfortable working height. The RHS suggests widths under 1.5m so you can reach the centre without standing on the soil.
Longevity expectations: If you want a low-maintenance frame and are willing to monitor for rust, metal may appeal. If you prefer a natural look and accept periodic treatment or replacement, timber is well supported by RHS guidance.
Honey fungus risk: If honey fungus is present, the RHS recommends avoiding timber and choosing masonry or recycled plastic. Changing the frame does not remove honey fungus already present in soil and woody roots.

Pre-purchase checks for both types

For a timber bed, confirm whether the wood is pressure-treated or untreated. For untreated timber, choose a suitable species and thickness and allow for inspection and eventual repair; preservative is not compulsory. The RHS states that new treated wood is fine for edible crops, but you can line with plastic if you want extra caution. For a metal bed, check the material specification: galvanised steel, powder-coated steel or aluminium. Ask about coating thickness, whether drainage holes are included, and how cut edges are finished. Look for a warranty that covers corrosion, and read the manufacturer’s assembly instructions before buying.

No single material wins for every garden. Timber can be straightforward to repair or adapt, but its service life depends on the wood and construction. Metal offers rot resistance and a different aesthetic, but its long-term performance depends heavily on the coating quality and your willingness to inspect for damage. Match the material to your site conditions, budget and maintenance habits rather than chasing a universal best choice.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Pressure-treated timber raised bed kit: A pre-cut timber kit can simplify construction; compare actual thickness, joints and repair options. Confirm the timber is pressure-treated, check board thickness, and ask whether the kit includes fixings and a lining if you plan to grow edible crops. Search Amazon for Pressure-treated timber raised bed kit.
Galvanised steel raised bed kit: Metal offers rot resistance and a different aesthetic, but coating quality is critical for longevity. Verify the steel is galvanised or powder-coated, check whether drainage holes are pre-drilled, inspect edge finishing for sharpness, and ask about the corrosion warranty. Search Amazon for Galvanised steel raised bed kit.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.