Plumbago auriculata (also P. capensis ) Cape plumbago
Hardy, evergreen; blue or white flowers
Next to oleander, cape plumbago could be the most widely planted shrub growing along the banks of Southern California freeways. Its bright sky-blue flowers bloom in clusters among the light-green, airy foliage. Not particular about the soil it lives in, it has low water requirements once it is established (it's listed in El Modeno Gardens' "Water Conservation Guide," available at most nurseries).
But cape plumbago seems to be underused by gardeners, probably because it is a fast, aggressive grower, bounding quickly to 10 or 12 feet and invading and growing up through neighboring shrubs. For large yards, this can be a plus; for smaller areas, cape plumbago should be pruned hard, to any shape, once a year. It's good on slopes and against walls and loves the heat.
A prolific bloomer, cape plumbago flowers year round in frost-free areas. Besides blue, flowers also can be on the gray side of white. At the nursery, look for plants in bloom to make sure you like the color. A drawback: After blooms fade, they do not self-clean, clinging to the plant and turning brown within the foliage.
If planted in the fall, cape plumbago will be established by spring--and then take off. It is sold in 1- and 5-gallon containers.