How to build a raised bed

Have you ever planted a vegetable bed full of fresh salad, only to find it stripped bare by slugs overnight? Then we’ve got a reliable tip for you. Unlike conventional methods of keeping slugs at bay, which only work to a limited extent, a raised bed offers a secure way to protect your plants.

Contents:

Tools and materials required

The substructure

The box frame

Assembly

Tools

Materials

4 wooden posts, approx. 50 mm diameter and 900 mm length
1 base panel (spruce or plywood), 1.5 m long × 50 cm wide × 16 mm thick
2 long side panels (spruce or plywood), 2 × 1.5 m long × 25 cm wide × 19 mm thick
2 short side panels (spruce or plywood), 2 × (50 cm + 2× panel thickness) long × 25 cm wide × 19 mm thick
Square timber, e.g. 25 × 25 mm, total 4.6 linear metres
4 large plastic flower pots
1 small plastic flower pot
Insulating foil, 2.2 m long × 1.2 m wide
Stainless steel or galvanised screws, e.g. 3.5 × 40 mm
Drawing pins

The Substructure

To begin, you will need wooden posts with a diameter of approximately 50 mm. The most suitable materials are timber species that are relatively resistant to decay yet remain affordable, such as spruce or Douglas fir. Pressure-treated posts are also a very good option. We do not recommend using hardwood offcuts such as beech or apple wood, as these tend to rot within a few months in direct ground contact.

You will need four posts, each approximately 900 mm long and pointed at one end. A point can be easily formed using a hatchet, such as a forest axe or joiner’s hatchet, by making angled cuts. It is best to place a board underneath to avoid damaging the cutting edge on the ground.

For cutting the posts to length, use a coarse Japanese saw such as the Silky Tsurugi 285, or, if you prefer a European alternative, a standard handsaw.

The overall height of the bed is calculated at 950 mm but can be adjusted individually depending on body height.

These posts are driven into the ground at a distance of approximately 10 cm from each corner of the base panel. To achieve the target height of 950 mm with 900 mm posts, around 200 mm must be driven into the soil. A sledgehammer is best suited for this task. If you are working in stony soil, pre-drilling or loosening the ground with a ground breaker can be very helpful.

Bulding the box frame

For this step you will need spruce boards; plywood is also a suitable alternative. The size of the box can be chosen individually. In this example, we are working with a length of 1.5 m and a width of 0.5 m. The height of the box should be around 25 cm.

We start with a base panel made from weather-resistant glued spruce. Alternatively, you can use plywood, which does not absorb moisture as easily and is therefore less prone to rot than materials such as MDF or chipboard. The base panel measures 1500 mm in length and 500 mm in width.

First, you will need a small, sturdy plastic flower pot. In the base panel, cut a hole close to one corner using a jigsaw, matching the diameter of the pot without its rim. If you do not have a jigsaw, simply drill a series of holes along the outline and finish the cut with a rasp.

Square timber strips (25 × 25 mm) are then screwed flush to the underside of the base panel along the outer edges. These act as fixing battens for attaching the side panels.

For fastening, stainless steel screws are recommended, as they are corrosion-resistant and significantly more durable than standard screws.

The long side boards, previously cut to length, are then screwed end-on to the base panel through the prepared square timber battens. For additional stability at the corners, an extra length of square timber can be fitted to these side boards.

Next, measure the width and cut the second set of side boards to size before screwing them in place.

The entire upper frame is then placed onto the four base posts and aligned using a spirit level.

Adjustments are straightforward: any post that sits too high can simply be driven further into the ground. To ensure proper drainage, a slight slope is required, so the posts should be aligned accordingly.

Before assembling the raised bed completely, the four flower pots are placed upside down over the posts. Make sure they are positioned at an even distance from the posts. The pots are then fixed in place with a screw. This acts as our slug barrier.

Assembly

The box can now be fixed to the posts from the inside using four long screws. It is essential to pre-drill through the base panel and the flower pots beforehand, otherwise the pots may crack when the screws are driven in.

Next, line the interior with a heavy-duty waterproof sheet, such as insulating foil. This protects the panels and timber from moisture and prevents premature rotting. Do not use nails or staples on the inside; instead, simply hold the foil in place with soil once the bed is filled, as any punctures would allow water to reach the base panel.

To protect against rainwater and irrigation water, the excess foil is folded over at the edges and fixed on the outside using drawing pins. The previously cut opening is then reopened with a knife, and the flower pot is inserted or alternatively bonded in place with silicone. This completes the drainage outlet.

Finally, fill the bed with garden soil, and you are ready to plant your salad.

With a raised bed, you protect your back—and you no longer have to share your lettuce with hungry slugs.