USDA zones are winter hardiness zones. They are useful for determining which plants will survive your winter, but they are not as helpful for summer survival. Zone 7 runs in a line from NJ across VA and TN to OK and the TX panhandle. But whereas NJ may get up to 50" rain per year, TX zone 7 may get between 16" and 24". Plants advertised as drought tolerant in the east may likely require irrigation in the west.

Talk to your neighbors about what grows well for them. Neighbors will also know when the best time to plant is. Talk to local nursery people (not big box nurseries) for which plants they recommend. Visit a local arboretum or botanical garden. Here is a LINK to find some in your area.