Hugelkultur: how to build a raised bed from logs and woodchip

Hugelkultur (German for "mound culture") means burying wood under soil to make a raised bed. The wood rots slowly, soaking up rain and releasing it in dry spells, and feeding fungi and worms as it goes. A well built bed needs little watering after its first year.

Hardwoods that rot at a steady rate are best: alder, birch, beech, oak, maple, and fruit woods. Half-rotted logs are better than fresh ones. Tree surgeons often have exactly this: rounds too awkward or too punky to sell as firewood.

• Avoid fresh willow and poplar, which can sprout. Dead or seasoned is fine.
• Avoid yew, and walnut, which releases a compound that holds back other plants.
• Conifers work but rot slowly and can make the bed acidic.

1. 1Mark out a bed about 1 to 1.5 m wide, as long as you like. Run it along the contour on a slope.
2. 2Lift the turf and set it aside. Dig down 20 to 30 cm if you can; you can build on the surface too.
3. 3Lay the biggest logs in the base, packed close. Soak them well.
4. 4Fill the gaps with branches and brash, then a thick layer of woodchip.
5. 5Add green material: grass cuttings, manure, kitchen scraps. This gets the rot going.
6. 6Lay the turf back on, grass side down, then 10 to 15 cm of compost and topsoil.
7. 7Mulch the top with woodchip to stop it drying out and eroding.

Tip: A bed settles a lot in the first two years. Build it taller than you want it.

In the first year, the wood is still drawing nitrogen. Hungry crops like brassicas can struggle, so start with squash, courgettes, potatoes and beans, which cope well, and plant the top and the sunny side. From the second year on, most crops do well.