Pots and Summer Heat

I know it’s not planting season yet, but I thought I’d start researching now so I’m ready come early spring.

I inherited five extra-large unglazed planter pots from my parents, which I love the look of. Trouble is, I don’t know what to plant in them.

I go out of town for a few weeks every July and don’t want to need to have someone water my plants every 2 days. This year, I planted Mexican tarragon, Texas milkweed, and Blackfoot daisy and they all seriously struggled in the heat, even with my neighbors watering every 3-4 days. They looked downright sad and didn’t start to look okay or bloom well until October.

Since these are all perennials, I’m going to try moving them to the ground – where they’ll likely fare better – in spring, but what should I plant in these darned pots that won’t require constant watering? Am I limited to succulents only?