Finally, the time is here: In the Rockies, go ahead and start those tomatoes!
In other regions of the West, May is a good time to experiment.
In Southern California, try subtropical fruit (like bananas, or cherimoyas); in Northern California, shop for kousa dogwoods; in the Southwest, consider a new prairie switch grass; and in the Northwest try some unusual summer bulbs (like Chinese ground orchids).
All zones should consider growing a tower of flowers. The tower at left is covered in Mandevilla, a subtropical perennial. (See how to make your own tipi trellis.)
Get more info on what to do in your own region of the West: