There is, of course, no one approach that works with all women. The only thing we can do is project ourselves into the situation and speculate how we would feel. Especially if, as you suspect, she's already been through some stuff, she might feel intimidated if you come on too fast. (You also don't want to move too slowly, and let the chance slip by. It's a balancing act.) Start by smiling and waving, tell her your name, and see how she responds to that. If you happen by as she's gardening, you might compliment the job she's doing and ask her a question about her plants.