Mediterranean natives; hardy to 15°F/–9°C. Grown with borderline success in Zones 4 and 5. In their favored dry-summer climate, they are carefree shrubs bearing a profusion of showy flowers for a month or more from spring into early summer; may also bloom sporadically at other times. In some rockroses, leaves are coated with a perfumed resin; others have foliage covered with gray wool. When plants are out of bloom, their soft green, silver, or grayish foliage and mounded form add subtle color and texture to the landscape.
Sun loving, fast growing, tolerant of aridity. Accept poor soil, cold ocean winds, salt spray, desert heat. Often planted in fire-hazard areas. Good erosion-control cover for dry banks. Useful in big rock gardens, in rough areas along drives, in wild plantings. Taller kinds make attractive informal hedges. Give plants well-drained soil if they will be watered. When locating in an area that won’t be irrigated, take particular care not to plant root-bound plants; cut circling roots and spread out the mass so roots can grow down to lower soil levels.
Most rockroses resent hard pruning. To keep plants vigorous and neat, periodically cut out a few old stems. Tip-pinch young plants to thicken growth, or give a light overall summer shearing to new growth and stems that have not become woody. If plants become woody and sparse after several years, it is often easiest to replace them.
Compact growth to 3–5 ft. tall with equal spread. Fragrant leaves are dark green above and lighter beneath; 3-in.-wide flowers are white with a dark crimson spot at each petal base. ‘Blanche’ grows to 8–12 ft. tall and 6–8 ft. wide, and bears 4-in. pure white blossoms. C. l. petiolatus ‘Bennett’s White’ has 3–4-in. flowers resembling those of Matilija poppy (Romneya coulteri), with wavy, crepe paper–textured petals around a large cluster of yellow stamens. Good hedge or background shrub for dry areas.
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