Drought tolerant edibles
Hey everybody, I'm new to Gardenweb and I'm beginning my first job and I want to make this 60 ft x 12 ft hill (at a 3:1 slope) as drought tolerant as possible while still using as many edible or medicinal species as possible. Mexican Elderberries, Yuccas, Joshua Trees are the natives around here... Lots of Manzanita and Sagebrush, even white sage. Winters can get down to about 20 as the extreme... average low about 25... Summers can get 110. Rain can range anywhere from 2" to 16".
I want to create a rich organic sponge in the soil with plenty of mulch to hold water, and eventually want to make the hill free of any irrigation. I'm either going to do swales or terraces on the hill in order to hold water and nutrients...
So I have several questions... How long would most of the drought tolerant desert species need to be irrigated until they are established enough to go it alone, keeping in mind I am trying to establish the sponge effect? Does anyone have any good drought tolerant edibles that would fit this scenario? Any tips would be greatly appreciated. Thank you!