How to tell? We call the Sunset WESTERN GARDEN BOOK our 'bible'.Look for it in the store where you buy your plants. Some stores even keep a counter copy for reference, and believe me, if I come across a plant I don't know, that's where I will be looking.The WESTERN GARDEN BOOK is loaded with great how-to's as well as a complete index to plants and their care.
Other alternatives are to simply google it, if you happen to have a smartphone. Or, download a Q reader app and many of the plants are including digital information right on the label.A Q reader is an application for your smartphone that takes a picture of those funny-looking UPC like codes...you've seen them, they look like a square box with little boxes inside. The reader will decode the information that is stored in that graphic, and some will even take you to the website about that plant.