Hi Mary. It may be that you won't be able to keep them healthy in your extreme dry heat. You might try one container under a tree. Give it ice cubes in the evening during the summer heat. Just a few. It would cool the soil surface and give small amounts of water to the plants.
Do you have any photos of the ones you lost? I think some are more tolerant of heat than others. Like the arachnoideum types.
What are your winter temperatures like?
