Building a Raised Bed: The Complete Construction Guide
From cutting the timber to correct layered filling – how to build your wooden raised bed
Disclaimer
This guide has been prepared with great care. Nevertheless, we accept no warranty for the accuracy, completeness or currency of its contents. You follow this guide at your own risk – any liability for personal injury, property damage or financial loss arising in connection with its use is excluded. The contents do not replace professional advice for your individual situation. Always observe the manufacturer instructions of your tools and materials as well as applicable local regulations (e.g. building codes, neighbour law, utility line enquiries before digging). Work on electrical, gas or water lines and on load-bearing structures must only be carried out by qualified professionals.
From cutting the timber to correct layered filling – how to build your wooden raised bed
A raised bed is one of the most rewarding DIY projects in the garden: it can be built in a weekend, needs no foundation and, thanks to the decomposition process inside, provides excellent growing conditions from the first season. The classic construction from wooden planks is achievable even for beginners with basic tools. A working height of 70–90 cm and a width of 100–120 cm has proven ideal – that way you can comfortably reach the middle from both sides.
Tools
- Cordless drill/driver
- Saw (circular or mitre saw)
- Spirit level
- Folding rule and pencil
- Staple gun for the liner
- Spade
Materials
- Wooden planks e.g. larch or Douglas fir (approx. 30–40 mm thick)
- Squared timber 7×7 cm for the corner posts
- Stainless or galvanised screws
- Vole mesh (fine wire mesh)
- Dimpled or pond liner for the inner walls
- Filling: branches, green cuttings, leaves, compost, planting soil
Step by Step
Choose and prepare the location
Ideal is a level, sunny spot oriented north-south. Remove the turf on the footprint and level the ground. The raised bed later sits directly on open soil – so soil organisms can migrate in and water can drain away.
Cut the timber
Cut planks and corner posts to size or have this done at the DIY store. For a bed of 200×100×80 cm you need four corner posts of 80 cm and, depending on plank width, 10–14 planks. Break the cut edges with sandpaper.
Assemble the frame
First screw together the two short side walls: fasten planks flush to two corner posts, working at right angles with the spirit level. Then the long planks connect the two side panels into a rectangle. Use two screws per connection; pre-drilling prevents splitting.
Install vole mesh and liner
Line the entire base of the bed with vole mesh and staple it to the bottom planks – otherwise rodents will enjoy your root harvest. Staple dimpled liner to the inner walls (dimples towards the wood). The liner keeps soil moisture away from the timber and considerably extends its life. Important: line only the walls, not the base – water must drain away.
Fill in layers
The classic raised bed is filled in 4–5 layers from coarse to fine: at the bottom 20–30 cm of coarse tree and shrub cuttings for drainage, then inverted turf or green cuttings, then semi-mature compost or leaves, and finally 20–30 cm of quality planting soil. The decomposition of the lower layers generates warmth and nutrients – a turbo for your vegetables.
Plant and maintain
In the first year, the bed is especially nutrient-rich – ideal for heavy feeders like tomatoes, courgettes or cabbage. As the filling settles by 10–20 cm over the first season, simply top up with compost and soil the following year.
Safety First
- Wear safety glasses and hearing protection when sawing and sanding; secure workpieces properly.
- Ensure safe guidance when cutting with a circular saw – if in doubt, use the DIY store cutting service.
- Do not saw pressure-treated timber without a dust mask; do not burn offcuts, dispose of them properly.
- When removing turf, watch out for buried lines (irrigation, power cables for garden lighting).
Mistakes You Should Avoid
Sealing the base with liner
Lining the base of the bed with foil creates waterlogging – the filling rots instead of composting. Only the side walls get liner; the base stays open (with vole mesh).
Filling only with potting soil
A raised bed filled entirely with bought soil gives away its biggest advantage: the decomposition warmth and nutrient release of the layered structure. It also becomes unnecessarily expensive.
Building too wide
At more than 120–130 cm width you can no longer comfortably reach the middle – and end up stepping on the soil after all. 100–120 cm with access from both sides is the proven dimension.
Common Questions
Which wood is best for a raised bed?
Larch and Douglas fir are the standard: naturally durable, usable untreated and affordable. Spruce is cheaper but lasts noticeably shorter even when coated. Many deliberately avoid pressure-treated timber right next to vegetables – with a dimpled liner as separation it is acceptable.
How long does a wooden raised bed last?
Built from larch or Douglas fir with an inner liner, 10–15 years are realistic. Without liner and from spruce it can be as little as 5 years. The key is that the timber has no permanent contact with moist soil.
What goes in the bottom of a raised bed?
The bottom layer consists of coarse tree and shrub cuttings – it provides aeration and drainage. Above that come green cuttings or inverted turf, then compost or leaves, and planting soil on top.
Do I need a foundation for the raised bed?
No. A raised bed sits on open, level garden soil. Only on patios or sealed surfaces do you need a closed base tray with drainage – but then the classic layered filling does not work.
When is the best time to build a raised bed?
Autumn is ideal: leaves and shrub cuttings are available as filling material, and the filling can settle over winter. The bed is then ready for the spring planting season.
When is a professional worth it?
Would you like several raised beds, an edging of natural stone or corten steel, or should the raised bed be part of a complete garden redesign with paths, borders and irrigation? Then we are happy to plan it with you – from ground modelling and masonry raised beds to automatic drip irrigation. We also handle heavy earthworks and the delivery of large quantities of substrate with our machinery.
