Build a hügelkultur bed — step by step

A hügelkultur bed is more than a heaped-up mound of soil. It's a mini compost reactor: inside it, wood rots, releases nutrients for years and stores water like a sponge. Built in 1–2 days, productive for 3–5 years without fertilising.

Why a hügelkultur bed?

• Water store. The buried wood soaks up water like a sponge — even in dry summers the root zone stays moist.
• Long-term feeding. Decaying wood and organic material release nutrients for 3–5 years. You don't have to feed anything in.
• Earlier warming. The mound shape gives more sun-facing surface, and rotting heat builds up inside — the harvest starts 1–2 weeks earlier than in a ground-level bed.
• Easy on the back. 23.6 in–39.4 in high — comfortable to work without bending.
• Planting area +30 %. The slopes are plantable too — more yield per square metre of footprint.

What you need

For a classic 13.1 × 3.9 ft hügelkultur bed (the standard size in the Garden Planner):

• Wood — old branches, log sections, root stumps. About 264 gal. Important: no walnut, no fresh oak (too many tannins), no black locust. Beech, birch, fruit wood, poplar, willow work well.
• Shrub prunings — leafy branches, fresh shoots. 132 gal.
• Leaves and straw — autumn leaves, leftover straw bales. 132 gal.
• Half-ripe compost — 79 gal.
• Topsoil — about 132 gal as a top layer.
• Tools — spade, wheelbarrow, maybe loppers.

Choosing the spot

• Sunny (6+ hours of direct sun)
• Long axis north–south — both slopes get even light over the course of the day
• Not directly under trees — root competition
• On a slope: mound across the slope, not along it (prevents erosion)
• Water access nearby — for the first season's watering-in

Build — layer by layer

Layer 1: root layer (bottom)

Cut out the turf where the bed will go (flipped over later as the top layer). Dig down 7.9 in. Set the excavated soil aside — it goes back on as the top layer.

Layer 2: wood core (19.7 in)

Lay thick pieces of wood lengthways (north–south) into the trench, a dense layer. Pack smaller branches in between — fill the hollows. This wood will store water and release nutrients for years.

Layer 3: shrub prunings + leaves (7.9 in)

Loose shrub prunings on top, lightly compress with your feet. Water it in well — important, otherwise air pockets form that later lead to settling.

Layer 4: turf flipped over (3.9 in)

The turf cut out at the start — flipped over (grass side down) onto the shrub prunings. That way no grass barrier forms and the grass rots down as well.

Layer 5: half-ripe compost (5.9 in)

Activates the rotting process. Important: half-ripe, not finished — the micro-organisms should keep working.

Layer 6: topsoil (5.9 in)

Top layer: sieved topsoil. Mixed with a little ripe compost if you have it. This is the planting zone.

Finished mound height after settling: about 31.5 in. In the first season the mound drops by ~7.9 in — that's normal. The following spring, top it up with 3.9 in of compost + topsoil.

First season: what to grow?

In the first year the mound is low in nitrogen — the rotting wood binds nitrogen. So no Heavy feeder like tomatoes, cabbage, squash. Instead:

• Potatoes (they break up the soil at the same time)
• Beans and peas (they fix nitrogen)
• Lettuce, spinach (light feeders)
• Herbs

From years 2 and 3 the mound is at its peak — anything goes. From years 5–7 it settles noticeably, and you rebuild it or carry on using it as a strawberry/herb mound.

Maintenance

• First season: water regularly — the wood has to soak up to capacity first
• Mulch with straw or wood chips (2.0 in) — holds moisture, cools in summer
• In autumn: green manure (Phacelia, lupins) to protect the soil over winter
• Every spring, 2.0 in of compost on top — compensates for the settling

The hügelkultur bed shares its build logic with the raised bed (a standing hügelkultur in a box) and lives off the compost that kick-starts the rot in the core. In the Garden Planner hügelkultur beds are the default form — 13.1 × 3.9 ft, ideal for crop rotation by Model B.