Rosemary is a tender, perennial herb with more than 45 cultivars and belongs in the family lamiaceae along with mints. Plants are broken into two categories including upright (Rosmarinus officinalis) and prostrate (Rosmarinus prostrates) or creeping. Rosemary is hardy growing in USDA planting zones 7 through 10, with only the cultivar 'Arp' tolerating the cooler temperatures of planting zone 7. Herbal medicines, food recipes and cosmetics utilize the aromatic herb.
'Tuscan Blue' (Rosmarinus officinalis 'Tuscan Blue') is a tall and erect cultivar of rosemary that is a perennial. It blooms with lavender-blue, tubular-like flowers with a lower lip during winter and springtime. The flowers are bigger than other rosemary cultivars. 'Tuscan Blue' works well as a background plant in herb and flower gardens, in containers, as an accent plant or in small hedges.
'Tuscan Blue' is a large variety of rosemary growing anywhere from 4 to 6 feet in height with a spread of 4 to 5 feet. As all rosemary cultivars, it prefers growing in full sun conditions, not tolerating total shade. It is drought tolerant, but plants should not be allowed to completely dry out or kept in saturated conditions. This evergreen herb is cold hardy to 20 degrees F, and cooler areas should grow the herb in a container for winter protections. The high salt tolerance of 'Tuscan Blue' makes it suitable for coastal plantings.
Arp (Rosemarinus officinalis 'Arp') is the cold hardiest of all rosemary cultivars as it tolerates temperatures to minus10 degrees F. It will require winter protection with a covering of mulch or burlap wrapping when temperatures fall dramatically. 'Arp' is another tall variety of rosemary with an upright habit. Its leaves are gray-green and have a lemon scent. Blue flowers bloom winter through springtime. It is suitable for herb gardens, containers and as a background plant in flower gardens.
This cultivar grows 3 to 5 feet tall and spreads 2 to 3 feet. It prefers growing in full sun conditions in a wide range of well-draining soils. It's drought-tolerant, but do not allow the soil to fully dry out or stay saturated with water. As with most rosemary cultivars, 'Arp' has a high tolerance for salt.
Creeping rosemary (Rosmarinus officinalis 'Prostratus') is larger in its spreading habit than its height. Creeping rosemary has a variety of cultivars. It is a tender, evergreen, perennial herb with smallish, needle-like foliage. Plants bloom in colors of lavender winter throughout springtime. The plant is suitable for use in rock gardens, dry gardens, borders, hanging baskets, slopes or planted inside containers.
Creeping rosemary spreads up to 3 feet and stands 6 to 12 inches tall. It prefers growing in full sun in well-draining soil mediums. It tolerates even the poorest soil conditions. Gardeners should water the herb regularly, not allowing it to become flooded with water or completely dried out. It has a high salt tolerance, making it well suited for planting along coastal areas.