Hi Arlene.
The lilies where here when we bought the place in 1999. It wasn't until 2000 that we realized they were here. Everything was dead, hadn't been watered in a number of years. We started watering the summer of 1999. Come spring time these lilies were coming up everywhere in that area.
I think the original planting was done in 1950.
They are really tough plants and have survived here down to 0°F, plus heavy rains from winter through most of the spring. July and August is our drought season and they get almost no water.
I think if a person planted a border with about 10 plants it wouldn't take long to fill in and create a nice display. The birds love them, hummers when in bloom and goldfinches when they have gone to seed.