I'm planning a small grove of domestic Plums in the understory of three Cedar Elms. Native Texas Persimmon are already there as understory fruits. We had a few native Plums on our land but they seem to have died. In addition to the domestic Plums, I'll be planting as many support species as I can squeeze in there, plus some annual vegetables. I'll be creating a berm and basin for this planting, and building a buried wood bed for the Plums, which I will plant in the Fall or next Winter. Arrows indicate water flow on this very slight slope:
Finished the excavation of the plum hole; I dug down until I hit a rock shelf, about 18 inches max. Filled the hole with wood. The plums themselves will be planted just uphill of the buried wood, but not on it, as I don't want them to settle below the surrounding grade.
Finished fencing the Plum Project, and planted it (except not the plums). Some of the seeds planted: Honeylocust, Palo Verde, Moringa, False Indigo Bush, Mexican Bird of Paradise, Esperanza, Cowpea, Black-eyed Pea, melons, winter squash, tomatoes, peppers, and a mixture of flowering plants and some old things I had in the fridge.
Upon observing this space as the overstory leafs out and grows, I'm thinking it would not be prudent to try to grow more trees here, but instead move down to the shrub layer for fruit. So this thread should be retitled "Understory Fruit Project."