Recently I turned our round raised bed into a Lesotho style keyhole garden (minus the wedge) as an experiment in 'arid' gardening, because let's face it with multiple days in a row of 40+ heat here in summer, temperate gardening techniques aren't really adequate.
For those of you who aren't familiar with the concept, Lesotho (in Africa) has a temperature range of 40+ during the day, down to -15 degrees at night. Some years ago the people were in dire straits, as their crops weren't producing and a large proportion of the population was malnourished. That was until they developed the idea of a keyhole bed.
The keyhole bed is a raised circular bed (made of stones, bricks etc) with a wedge cut out for access to it's centre. There, in the middle is a basket which sits through the core of the bed. The bed is built up in layers (like no dig gardens) but the inside is raised so the dirt/straw etc slopes down to the outer edge of the circle. Food scraps, manure, straw, compost etc is placed into the central basket, and grey water is poured into the basket which ensures the bed is gravity fed and moist right to outside, whilst fertilising as the baskets contents break down.
There are a number of great sites on this method. Here a link to one which shows you how a group of school children did it.
I planted some seeds and a few plants in mine, and it's the most exposed garden bed I have - yet seems to be doing really well so far. I'm still top watering though as I haven't managed to fill the basket (chook wire in my case) to the top yet so the gravity fed aspect isn't functional yet.
Just a tip though to any of you thinking of giving it a go....cover each layer of food scraps with sand, clippings or something...as the smell from mine wasn't terrific after a week or so in the sun until I sorted it!
Photos to come in a future post.