I live here in florida and we have the same issues with sun and heat, but I do have humidity. I have junipers growing in bonsai soil, but to tell you the truth, they really do better in more of a soil mixture. What I do, is I get a bag of soil that is more for trees and shrubs at one of the stores, it usually has a good amount of pine bark in it. Then I either grab a bag of lava rock, or pea gravel. Lay down a row of the stone in the pot then start filling in a mixture of the two, with a little more soil than rock. Also, you might grab some spagnum moss and put arround the base of the trunk on top of the soil, to help keep the tree moist, especially if repotted. I would water at least every other day,funny thing about junipers is that they will take alot more watering than most plants, but dry out very fast. Keep out of the full sun for a while, will grow fine in partial shade and mist them as much as possible. Their foilage likes a lot of moisture, which sound funny, growing in the desert, but they do...