I can't specifically answer your question, because I'm just a novice myself, but I have some ideas for you. My first thought is just too hot -- don't expect your Georgia flowers and plants to do well here. They say not to plant anything in June here at all. Heat stress kills 'em.

Start to learn about native desert plants --they're the only ones to do well unless you really want to water, water, water, and baby, baby, baby them. And water is very precious here!

I am learning and have found several good resources. Look on the web for El Paso Master Gardeners and Dona Ana County Master Gardeners. Texas A&M website also has great info.

There are also several good books about southwest and desert gardening. None of them have zinnias.

thank you for the advice. i researched a lot before we moved here and zinnias were on most of the lists of plants that do well in the desert. i just think they're not getting the nutrients they need because i didn't amend the soil before i planted them. that's on the list for anything i plant next year!