No, keyhole gardens do not have to be round. The keyhole garden shape that everyone pictures is just the classic version, not a hard rule. What makes a bed a keyhole is the center compost basket and the wedge cut into one side. The curve of the outer wall has nothing to do with it.
My own bed proved that fast. I dug the footing and lined the 6-foot (2-meter) stone wall in the back corner of the yard. I built it waist high so I would not have to bend over the soil. The curved wall kept fighting the straight fence behind it, and the stones would not sit flush. So I squared off that one corner and let the wall meet the fence in a clean line. I set the center basket and the notch in the exact same spots I had planned.
The squared corner changed nothing about how the bed worked. The soil still drank from that basket. Every plant still fed off the compost in the middle. I noticed the harvest from the squared side matched the curved side all season long. The outline bent to fit my fence, and the keyhole garden shape kept doing its job.
Here is the part that matters for your own bed. Every scoop of soil has to sit within arm's reach of the access notch. Every plant has to pull water and food from the central basket. That is the whole point of this design. Hold those two things true, and your outline can bend, square off, or run dead straight. You get the same easy care no matter which one you choose.
A round keyhole garden does this with a smooth circle and a slim wedge cut to the middle. The circle drops the basket dead center, so no spot sits more than 3 feet from your hands. But a circle is not the only way to hit that target. You can reach the heart of a square bed just as well. Keep the sides short and the center stays close.
The central compost basket and the access notch make a keyhole garden work, not the curve of the wall. Keep both in place and any outline holds up.
Modern growers have run with this idea. The team at Gardenary took the circular African keyhole bed and reframed it. They turned it into a square or rectangular raised bed. They kept the feeding basket in the middle and dropped the round wall. You get the same self-watering, self-feeding core in a frame built from straight lumber. That fits most backyards far better than a ring of stacked stone.
So match the keyhole garden shape to the space you actually have. A square or rectangular keyhole garden tucks tight against a wall, a fence, or the edge of a patio. You waste no awkward gaps in the corners that way. Save the round bed for open ground in the middle of your yard. The curve has room to breathe there, and it looks clean from every angle. Let your space pick the shape, and you will get more growing room out of it.
One rule does not bend, whatever outline you pick. Keep your bed narrow enough to reach the center basket without stepping on the soil. Three feet from the notch to the middle is about the limit for most arms. Stay inside that reach when you lay it out. Your keyhole bed will work as a circle, a square, or a long rectangle, and you will never have to crush a single plant to feed the basket.
Read the full article: Keyhole Garden: A Complete Beginner Guide
