Nothing beats California Lilac - Ceanothus for spectacular blue color! Ceanothus are native to California and grow to different heights. Some grow like a groundcover and some make 8 ft tall bushes. They also come in white. But I do love the blue. They are sometimes too drought tolerant for most home gardeners because we water too much. They will rot with too much water. Visit them in Spring at Ranch Santa Ana Botanical Gardens in Claremont to see their amazingness! And find a dry-ish spot in your garden for one.