How to Build and Fill a Raised Garden Bed: Step-by-Step Guide

A raised bed is easier on your back, warms up faster in spring than a ground-level bed and, thanks to its slowly rotting filling, often produces much bigger harvests. This guide shows you how to build and fill one properly, from choosing the spot to the first planting.

1. Choose the right location

Vegetables need light. Pick a spot with at least 6 hours of sun per day. Ideally, run the long side north to south so both sides get even light.

Also look for:

• level ground, or the bed will tilt as the filling settles
• water nearby, since raised beds dry out faster than ground beds
• distance from trees, whose roots love to grow up into the nutrient-rich filling

2. The right size

Dimension	Recommendation	Why
Height	80–90 cm	comfortable for most people
Width	max. 120 cm (max. 80 cm against a wall)	you can reach the middle
Length	150–250 cm	stable, enough growing space

For long wooden beds, add a cross brace in the middle so the sides don’t bow outwards under the weight of the filling.

3. Materials: wood, metal or stone?

• Wood (larch, Douglas fir): natural, easy to work, lasts 8–12 years with an inner lining.
• Metal (galvanised or Corten steel): very durable and modern, but heats up more in full sun.
• Stone or gabions: practically everlasting, but laborious and expensive.
• Composite/plastic: low-maintenance but less sustainable.

Avoid pressure-treated timber with chemical preservatives for wooden beds; you’ll be growing food in it.

4. Protect against voles and rot

Before filling:

1. Cut out the turf on the base area (you’ll use it upside down as a layer later).
2. Lay fine wire mesh (aviary wire, about 13 mm mesh) on the ground and bend it a few centimetres up the sides.
3. For wooden beds, line the inside walls with dimpled membrane, dimples facing the wood so air can circulate. Do not cover the bottom.

5. How to fill a raised bed

The secret of a good raised bed is layering. Coarse material at the bottom provides drainage; the rotting layers above supply warmth and nutrients.

Layer (from bottom)	Material	Thickness approx.
1	coarse prunings, branches, twigs	25–30 cm
2	upturned turf, leaves, grass clippings	15–20 cm
3	coarse, half-rotted compost or manure	15–20 cm
4	fine compost	10 cm
5	good garden soil or raised-bed soil	20–30 cm

Tip: Lightly tread down and water each layer. The filling will then sink less later.

If you don’t have your own garden waste, you can fill the bed with soil and compost only. It costs more but sinks less.

6. What to plant in year one

In the first year, the filling releases lots of nutrients, which suits heavy feeders:

• Tomatoes, courgettes, cucumbers, squash
• Brassicas (broccoli, kohlrabi)
• Peppers and aubergines in warm spots

From year two, add medium feeders (carrots, lettuce, chard, beetroot), and from year three, light feeders (herbs, peas, beans, radishes). Spinach and lettuce as an early spring crop suit any year.

Take care in year one with lettuce and spinach: in very rich filling they can accumulate nitrate. Harvest them in the late afternoon when nitrate levels are lower.

7. Care: watering, topping up, mulching

• Watering: raised beds dry out faster. In summer, water deeply in the morning rather than a little every day.
• Mulching: a thin layer of grass clippings or straw retains moisture.
• Topping up: each spring, top up the sunken soil with compost.
• Rebuilding: after about 5–6 years the filling has rotted down; empty the bed completely and layer it again.

Common mistakes

• Building it too wide: you can’t reach the middle.
• No wire mesh: an annoying mistake that is hard to fix later.
• Soil only, no drainage: waterlogging rots roots.
• Planting herbs in year one: Mediterranean herbs prefer lean soil and grow soft and weak in a fresh raised bed.