Richo Cech has some advice about how to cultivate them from seed, by planting in ashes, and a couple of other tricks. traditionalmedicinals.com He gets them to grow in Oregon. I got one to grow in a pot in coastal California, near Santa Cruz, but the season wasn't long
enough for it to flower, and I've had trouble getting them to start up here in the Rockies. But I am not a great gardener. For recovering the native populations, one of my pet theories is that some plants (and animals) that we think of as wild were actually semi-cultivated, and I suspect white sage is one of them. If you live in a white-sagey area, scarifying and spreading seeds under out of the way rocks while hiking would be a very good deed. If you grow some in your garden you will then have a cultivated source of seed. The leaves are too aromatic for cooking, in my opinion, but they would make a good
medicinal sage. I don't know the tradition, though, other than burning.