Carolyn,, ordinarily you would be right but she said it started dying within a few days after she bought it and right now,, Texas is not that hot !! Only 60`s to upper 70`s lower 80`s ! Even we can`t kill a plant that fast !
Two of my favorite posters, Carolyn and Mart, are giving great advice on this topic. As an experiment, I took my oven thermometer out and placed it against the house bricks, and at 3 this afternoon it registered 98 degrees, with the air (ambient) temperature at 80. Perhaps 98 isn't enough to cook a plant, but it would do a good job on me! Mart's point about the soil is a good one. I've purchased six packs of plants at Lowe's or Home Depot, brought them home and thought I didn't need to water since the top soil was damp. When I lifted one of the plants out of its cell to check the roots, I found the soil to be completely dry under the top 1/4" or less. I do hope your topiary survives and gives you years of pleasure. If not, you have learned and can use that when caring for your next plant. Please don't give up on growing greenery--there are few pleasures better than seeing something thrive under your care!
http://www.costafarms.com/plants/eugenia-topiary But this is a tropical from Australia !! I don`t think our temps would even make a dent !! However lack of water can cause this problem quickly !!