Garden-worthy plants show up at public gardens long before they reach the nurseries. Plectranthus ciliatus, shown at left, the star of the shade border at the University of California at Irvine Arboretum for the last several years, is a prime example. Its most obvious asset is its flowers--in a gorgeous goes-with-everything shade--which appear over an 8- to 10-week period in fall.

But P. ciliatus has many other virtues, says the arboretum's nursery manager, Laura Lyons. It tolerates most soils, has no disease or pest problems, and has no requirements other than regular watering and light feeding. Its foliage, with "lots of substance and attractive purple undersides," is exceptional, she says. Staffers at the arboretum prune the plant annually to keep it at about 3 1/2 feet wide and 18 inches high.

If you want it, though, you'll have to come to the Arboretum's Fall Perennial Sale to get it. Despite its sterling character, P. ciliatus is still rare in the nursery trade. The Huntington Botanical Gardens will also sell the plant at its big four-day fall plant sale, October 12 to 15; see Events for details. 10-3, October 21-22; $2. UC Irvine Arboretum (on Campus St., south of Jamboree Rd.), Irvine; (949) 824-5833.