Keyhole Garden Bed
A circular raised bed with a notched walkway and a central compost basket. You water and feed the basket, and nutrients leach out to the plants.
Estimated cost
$30 – $70
Estimated time
2 – 3 hours
Lifespan
5–10 years
Soil needed
About 1 cubic yard of layered compostable fill and quality soil
Weight empty
20–40 lbs for the frame
Weight full
1500–2000 lbs
Best for
Vegetables, herbs, and flowers in hot, dry climates
Placement
Full sun. Keep the keyhole opening on the north side in hot climates so the compost tower does not shade the bed.
Boards to Buy
| Boards to Buy | Quantity | What You Use Them For |
|---|---|---|
| Stacked stones, bricks, or wood boards | Enough for a 6 ft circle | Retaining wall |
| Chicken wire or hardware cloth cylinder, 1 ft diameter × 3 ft tall | 1 | Central compost tower |
| Cardboard or newspaper | Several sheets | Sheet mulch base |
| Compost, aged manure, topsoil, straw | 1 cubic yard total | Layered fill |
- ·Optional: small hinged lid for the compost tower
Steps
- 1Mark a 6 ft diameter circle on flat ground.
- 2Build the outer wall about 24–30 inches tall using stone, brick, or wood.
- 3Leave a 2 ft wide notch in the circle for a keyhole walkway pointing toward the center.
- 4Lay cardboard or several layers of newspaper over the entire floor to smother grass and weeds.
- 5Set the wire cylinder in the center to form the compost tower.
- 6Layer fill materials like a lasagna: straw, leaves, compost, topsoil, repeating until near the top.
- 7Water each layer as you build so the bed settles evenly.
- 8Fill the compost tower with kitchen scraps, coffee grounds, eggshells, and garden trimmings.
- 9Top the bed with 3–4 inches of quality soil or compost.
- 10Plant shallow-rooted crops the first season; deeper roots can follow in year two.
Tools needed
- ·Shovel
- ·Wheelbarrow
- ·Tape measure
- ·Work gloves
- ·Utility knife or scissors for cardboard
Common mistakes to avoid
- ·Building the circle too wide to reach the center
- ·Using the wrong materials in the compost tower — avoid meat, dairy, and oils
- ·Not wetting the layers as you build
- ·Planting deep-rooted crops the first season before layers have settled
Maintenance tips
Water through the central compost tower weekly. Add kitchen scraps to the tower each month. Top-dress with compost each spring.
Community builds
See how other gardeners built their keyhole garden bed — and share up to 3 photos of yours.
Sign in to view photos other gardeners have shared.
Sign in to share photos of your build.