There's a particular satisfaction in a raised bed made from timber that has already had one life. Scaffold boards with old cement splashes, decking boards gone silver in the rain, pallets pulled apart on a Saturday morning — all of it makes a growing space that costs very little and looks far better than a plastic kit. Build it properly, though, and it will outlast most of the shop-bought alternatives.

Why Reclaimed Timber Earns Its Place

Reclaimed boards are usually thicker than the flimsy planed timber sold for garden projects. A scaffold board is typically 38mm thick and 225mm wide, which is a genuinely sturdy edge to lean on and to hold back wet soil. Reclaimed stock is also cheap or free, and using it keeps decent timber out of the skip.

The trade-off is that you rarely know what the wood has been treated with. Old railway sleepers are the classic trap — many were soaked in creosote, which should never go near a vegetable bed. The same goes for chipboard, MDF and anything flaking or soft enough to push a screwdriver into. If it crumbles, it will not hold soil.

Good sources worth checking:

• Scaffold boards — 3.9m long, ideal for a bed 45cm deep when stacked two high.
• Old decking boards — thinner at around 28mm, fine for a low bed with plenty of corner posts.
• Pallet wood — free and plentiful, but thin, so best kept for a shallow 20cm salad bed.
• Skip and salvage timber — always ask before taking, and reject anything painted with unknown old coatings.

Sizing and Siting Before You Cut Anything

Keep the bed to 1.2m wide. That is the width you can reach across from either side without ever standing on the soil, which matters more than most beginners expect. Length is up to you, but work in multiples of your timber so you waste as little as possible.

For depth, think about what you want to grow. Around 20–25cm suits salad leaves, herbs, chard, radishes and most annuals. Go to 40–45cm for carrots, parsnips, beetroot and maincrop potatoes, which need a proper root run.

Position it in full sun — six hours or more in summer — and within easy reach of a tap or water butt carrying a hose. Then prepare the ground: lift the turf, fork over the soil beneath and roughly level it. It does not need to be perfect, but a bed that rocks will eventually twist and pull its fixings loose.

Cutting, Squaring and Screwing Together

Measure twice, mark a square line with a try square, then clamp a straight batten along the line as a saw guide. Support the far end of the board so the cut does not pinch the blade. A handsaw is perfectly adequate; a circular saw is quicker if you have one.

Cut four corner posts from 50mm x 50mm timber, each the full height of the finished bed. Screw your boards to the posts using 75–100mm exterior-grade screws, and always pre-drill near the ends of a board to stop it splitting.

Two rules will save you trouble:

• Stagger the joints — do not let corner joints line up vertically on both courses, or the bed will hinge apart.
• Check for square by measuring both diagonals. When they match, the corners are true.

If your bed runs beyond about 2m, add a mid-length post on the inside to stop the boards bowing outwards under the weight of wet soil.

Lining the Inside Before You Fill

This is the step most people skip, and it is the one that doubles the life of the timber. Staple damp-proof course membrane or heavy-duty geotextile around the inside face, folding it over the top edge. It keeps soil and moisture away from the wood while still letting water drain down through the open base.

If your bed sits on soil, leave the bottom open and let worms do the work. If it stands on paving or gravel, add a 5cm layer of gravel for drainage and drill a few holes along the lower boards.

For filling, a decent mix is roughly 60% topsoil, 30% peat-free multipurpose compost and 10% well-rotted manure or garden compost, with a handful of fish, blood and bone per square metre. A 1.2m x 1.2m bed at 45cm deep takes about 650 litres, so a bulk bag plus a few smaller ones. Add it in layers, watering and firming gently as you go, and stop 2–3cm below the rim so you can water without it running off.

Planting Up and Looking After It

Let the bed settle for a week, then top it up before planting. Salad leaves, herbs, chard, dwarf French beans, beetroot and spring onions all thrive in a first-year raised bed. Never walk on the soil — that is the whole point of the design.

Each spring, add a 5cm layer of compost. Beds settle by a few centimetres a year, so topping up is not optional. Check the screws each autumn and tighten any that have worked loose, and give bare timber a coat of a plant-safe wood oil if it starts looking dry. Looked after like this, a bed built from reclaimed boards in an afternoon will quietly keep producing for eight to twelve years.