I've seen Trillium grandiflorum growing wild here on shady southeast facing banks. They receive practically no direct sun while in growth. Summer gets no rain here for around three months. I've seen sources list Trillium grandiflorum to live in zones 3 to 9. I wonder if you grew it on the "cool" side of the house (North side?) in deep shade and plenty of water it would be happy? One technique you may employ for water retention in a dry climate is a trench bed. A deep trench, around a foot deep, would capture more rainfall (if any) and irrigated water while the sides protect the plants from drying winds. The bed is dug, the dirt taken out forms the walls. I believe it is how they grow things in the driest parts of Africa. I've tried this in our vegetable garden, it works well. Our recent summers have been three months of rainless 100 degree days, putting the technique to the test! Travis Owen Rogue River, OR amateuranthecologist.blogspot.com http://www.pacificbulbsociety.org/