Grow
Bed types: which one suits your soil, your water and your space
Bed type is not a style choice. It is a function of your soil, your water, your slope and your space — and one of the options was invented in Lesotho for exactly our conditions.
The short answer
Choose a bed type by constraint, not by preference. Good soil and space: in-ground or no-dig. Poor or compacted soil: raised. Water is the constraint: wicking beds. Water and space both constrained: a keyhole garden, developed in Lesotho for arid ground and greywater. No land at all: grow bags and containers.
Almost every gardening guide starts by telling you to build a raised bed. It is good advice roughly a third of the time, and the other two-thirds it is an expensive way to make your problem worse.
A raised bed drains faster and warms sooner. If your problem is heavy clay and cold, that is exactly what you want. If your problem is sandy soil and a dry season — which in inland South Africa it very often is — you have just built something that dries out faster than the ground you were trying to improve.
The keyhole garden, which is ours
This is the one worth knowing about, and almost nobody in South Africa writes about it properly.
The keyhole garden was developed in Lesotho by aid organisations working on food security in arid conditions with very little water. It is a circular raised bed, roughly two metres across, with a wedge cut out to reach the middle — the keyhole — and a basket of compost and waste at the centre.
You feed the basket with kitchen waste and greywater. Nutrients and moisture move outward through the bed. It concentrates water where roots are, it recycles waste on the spot, and it produces a surprising amount from two square metres.
It is Southern African by origin, it is designed for exactly the conditions most of this country has, and the search demand has tripled in a year. That we have to explain it at all is a fair indictment of how much of our gardening advice is imported.
The wicking bed, for a dry season
A wicking bed holds a reservoir of water beneath the growing medium, separated by a geotextile layer. Water moves upward by capillary action as the soil dries. You fill the reservoir rather than watering the surface.
The effect in an inland South African summer is dramatic — watering intervals stretch from daily to weekly, and there is almost no evaporative loss because the water is under the soil rather than on it.
The one thing that must be right is the overflow. Without an overflow at the top of the reservoir, the bed waterlogs, goes anaerobic and sours. It is a single 20 mm hole in the right place and it is the difference between the design working and rotting.
Where to start if you have nothing
Grow bags. `grow bags` returns 320 searches a month here at a keyword difficulty of 4, which tells you how underserved the entry point is.
They are cheap, they need no construction, they can be moved to follow the sun, and if you are renting they go with you. The only real drawback is watering demand — a fabric bag in an inland South African January will need water every single day. Group them, mulch the surface, and stand them where they get morning sun and afternoon shade.