For what it is worth, I live in Australia and we have extemely hot summers here. Last year I began my food forest (or what is supposed to become one!) by making triangular planters out of tightly bound small straw bales. Fruit trees and native trees were planted above ground in those planters and then I watered the straw, NOT the soil. Much to my surprise I only needed to water once every FOUR WEEKS, whereas the rest of my garden beds slowly deteriorated with watering every 2 to 3 DAYS! It is astonishing how much water a straw bale is able to take up and then slowly disperse; even the hottest days produced no noticeable heating up of the soil within the triangle either so insulation-wise it works a treat as well. All up, I handwatered that area 3 times over summer, the little rain we get over summer also meant that the bales are still in pretty good shape, one year after having put them down. I have also created a more traditional vegie bed but with walls made out of straw and this too required very little watering, not as good as the triangles though. In the past few weeks I have begun an orchard as well, but instead of triangles, the planters are rectangular. In this way I hope to plant 10 fruit trees reasonably close together (5x2 rectangles). Clearly this is very small-scale, but it may give you a few ideas.
Will be interesting to see what this year will bring, but so far it is looking good...
