I know it's a lot of trouble, but those plants should be exposed to their new situation very gradually. Expose them for and hour or two early and then put them inside by a window. Then after a day or two, increase the time outside. Continue that for a while until the plants are outdoors all day. Houston can be a tricky climate for cacti and succulents. The humidity keeps the soil from drying out properly, I think. I'd be really careful with water, especially until the plant has adjusted. Those columns store water, so they'll manage okay for a bit until you see how it goes. They are both attractive specimans so I hope they adjust well.
