Super Productive and Super Easy
What if there were a way to build a garden bed that was nutrient-rich and super productive, turned kitchen compost to plant food directly, didn’t need special dirt, and could be built out of scrap materials?
This is it: the keyhole garden—perfect for easy use in our increasingly hot and dry climate. A keyhole garden is shaped like a pie with a slice cut out. The wedge gives easy access to the heart of the bed and the compost cage, which is filled regularly with kitchen scraps and garden waste that percolates nutrients directly down to the root zone as it decomposes.
Keyhole gardens are incredibly easy to build. In Africa and elsewhere, many are built from debris, rocks, and sticks. Concrete blocks are also used. Start your own keyhole garden now and let it mellow until planting time.
For a 6-foot diameter garden you will need:
• 100 (8 inch x 8 inch x 16 inch) concrete blocks
• 25 (2 inch x 8 inch x 16 inch) concrete cap blocks
• 10 feet 36-inch chicken wire, 2-inch mesh
• ¾-inch and larger broken rock or inert debris
• Lots of cardboard, newsprint, straw, leaves, small branches, garden cuttings, kitchen scraps
• 2 bags (2 cubic feet each) garden soil or enough to build a 6-inch top dressing
For the optional season extender you will need:
• 3 pieces (½-inch) PVC pipe, 12 feet long
• 6 pieces (4-foot) rebar that will fit inside the PVC
• 2 pieces (10-foot x 30-foot) garden mesh netting
• 20 snap clamps for ½-inch PVC
BUILD THE WALLS
Clear and level ground.
Trace a 6-foot-diameter circle.
Mark the center.
Lay the first course of concrete blocks around the outside of the circle leaving a 32-inch gap for the keyhole entry.
Line the keyhole with blocks toward the center, ending with one block straight across the end.
Now stack blocks four high, alternating courses.
Cover with cap blocks.
BUILD THE COMPOST CAGE
Using the chicken wire, make a double 16-inch-diameter tube.
Wire it together, stand it in the center of the bed, and anchor it with rocks, both inside and out.
FILL THE BED
Cover the entire floor with rock.
Then line the bed and walls with wet cardboard.
Add small branches, leaves, straw, dry plant debris, kitchen waste, and torn newsprint in any order.
Layer in enough to fill the bed, watering after each layer.
Top with a layer of straw.
FILL THE COMPOST CAGE
Add layers of compostable kitchen scraps, leaves, straw, and shredded newsprint. End with a layer of straw to discourage flies.
Pour in a gallon of water. Continue to fill the compost cage regularly.
TIME TO PLANT
Add 6 inches of garden soil sloped away from the center.
Plant, then hand-water seedlings or set up a soaker hose on a timer.
BUILD THE OPTIONAL SEASON EXTENDER
To protect against sunscald, hail, and frost, install the optional season extender.
Drive the six rebar pieces in, equally spaced, around the edge of the bed.
Slip one end of the PVC pipe over one end of the rebar.
Bend the PVC to slip onto the opposing rebar to make an arch.
Repeat with all three pieces of PVC.
Cover the canopy with netting and hold in place with snap clamps.
To learn more, contact local keyhole garden expert Susie Robertson at youcancallmesusie@gmail.com or check out insteading.com/blog/keyhole-garden
