A raised bed is one of the best ways to start gardening. It has numerous advantages over a conventional flat bed and anyone — even a complete novice — can build one. In this guide we'll walk through the whole process from choosing materials to the first planting.
Why choose a raised bed?
A raised bed solves several problems at once. If your plot has poor, clay-heavy or stony soil, you don't need to laboriously improve it — you fill the bed with your own mix. A height of 40–80 cm means less back strain when working. The soil warms up faster in spring, so you can start the season 2–3 weeks earlier. And if you fill the bed correctly with organic material, it will self-generate nutrients and warmth for several years.
Raised beds are also more resistant to slugs (the edges can be fitted with copper tape), easier to cover with fleece against frost, and look neat and tidy in the garden.
Dimensions and materials
The recommended width is 100–120 cm — you need to be able to reach comfortably to the centre from both sides. Length is flexible, typically 200–400 cm. Height depends on your needs: 30–40 cm is enough for most vegetables; 60–80 cm is appreciated by those who don't want to work bent over.
The most common materials are:
- Timber — the most accessible and easiest to work with. Use larch, oak or black locust, which last 10–15 years without treatment. Spruce lasts 3–5 years. Don't use treated timber (old railway sleepers, pressure-treated wood) — it contains harmful substances that leach into the soil.
- Corten steel — a modern, aesthetically clean solution that lasts for decades. Corten steel gradually develops a rust-coloured patina and requires no maintenance.
- Masonry or gabions — durable but more expensive and labour-intensive to build. Suitable for permanent installations.
Construction
Choose a flat, sunny site. Orient the bed with its long axis running north to south, so both sides receive roughly equal sunlight. Remove the turf where the bed will stand — you can leave it in place, turned upside down, as the first layer of filling.
For a timber bed, planks 3–5 cm thick screwed to corner posts are sufficient. Line the inner walls with pond liner or woven landscape fabric — this protects the timber from soil moisture and extends its life. Non-woven fabric on the base will prevent weed roots from growing up through the bottom, while still allowing water to drain through.
Filling in layers
Correct filling is the key to success. The principle is simple: coarse material at the bottom, finer material at the top. The lower layers gradually decompose, releasing nutrients and generating warmth.
Layer 1 — Drainage and coarse material (20–30 cm)
Place branches, woody prunings, wood chip or old logs at the bottom. This material ensures drainage and generates warmth as it decomposes. Don't use conifer wood in large quantities — it acidifies the soil.
Layer 2 — Organic matter (15–20 cm)
Inverted turves, leaves, grass clippings, old straw. You can also include cardboard (unprinted) — it breaks down and retains moisture.
Layer 3 — Partially decomposed compost (10–15 cm)
Unfinished compost, old potting compost from containers, well-rotted horse manure. This layer provides the main nutrient supply.
Layer 4 — Top quality garden soil (20–30 cm)
Good-quality topsoil mixed with mature compost in a 2:1 ratio. This is the layer you'll be planting into. It must be deep enough that plant roots don't penetrate into the decomposing layers below.
After filling, water the bed thoroughly — the material will settle and you can top it up. Expect the bed to sink by 10–20 cm during the first year. In autumn or the following spring, top up with compost.
What to grow
In the first year the bed is rich in nutrients as the lower layers decompose. Take advantage of this and plant heavy feeders: tomatoes, courgettes, squash, cabbages, cucumbers. In subsequent years move on to less demanding crops: root vegetables, legumes, herbs.
A raised bed dries out faster because it has a larger surface area exposed to the air. Expect to water more intensively, especially in summer. Mulching the surface is essentially essential.
Maintenance
In autumn, clear away plant debris and add a layer of compost. In spring, lightly loosen the top 10 cm with a fork — don't dig deeply, as you'll disturb the layering. Check a timber bed regularly and replace any damaged planks. Renew or replace the inner liner if it begins to deteriorate.
A well-built and maintained raised bed will serve you for many years and reward you with abundant harvests. It's an investment that pays for itself.