The USA is separated into zones for planting. I am in zone 4+ and my flowers that are perennial will come through a harsh winter, since I am near the Canadian border. http://planthardiness.ars.usda.gov/PHZMWeb/
they love sun, but will grow in full shade, and they will certainly grow in California, They have been living in MN near the border of Canada, and come back through a harsh winter!