A few plants deserve special mention because they are widely grown (and loved) as perennials only in the West's mildest climates; in colder regions, gardeners use them as annuals. Following are a few of the most popular, listed by region where they're grown as perennials.
FOR MILD PARTS OF THE NORTHWEST AND CALIFORNIA
Cape fuchsia (Phygelius). Warm-toned tubular flowers in summer and fall; also good for zones H1-H2.
Twinspur (Diascia 'Ruby Field'). Salmon pink blooms June through fall.
Wallflower (Erysimum 'Bowles Mauve'). Nearly continuous bloom in mild climates.
CALIFORNIA'S LOW ELEVATIONS ONLY (EXCEPT DESERT)
Canna. Red 'Firebird' or 'The President'; orange 'Tropicanna' has striped leaves. Cannas are also grown as perennials in zones 6, H1-H2.
Million Bells (Calibrachoa). Profuse, bell-like blooms.
Bacopa (Sutera cordata). Trailing white flowers; June to frost. Perennial in zone H2.
Heliotrope. Scented, deep violet to white flowers come most of the year in warm areas; perennial in zones H1-H2.
Kangaroo paw (Anigozanthos). Deadhead the red, purple, green, or yellow blooms to keep them coming from spring through fall.
Nemesia caerulea 'Blue Bird'. Violet blue blossoms with yellow centers; perennial in zones 14-24, annual elsewhere.