Groundcover
Trailing Rosemary
Salvia rosmarinus 'Prostratus' · Lamiaceae
Also called: Prostrate Rosemary, Creeping Rosemary, Rosmarinus officinalis 'Prostratus'
Trailing Rosemary (Salvia rosmarinus 'Prostratus') is a low-water groundcover well suited to Tucson and the low desert. It grows to 12-24 in H x 4-8 ft W, with a moderate growth rate.
Trailing Rosemary at a glance
- Water use
- Low (established)
- Sun
- Full sun for dense, compact growth; tolerates reflected heat. Grows open and sparse in shade.
- Mature size
- 12-24 in H x 4-8 ft W
- Growth rate
- Moderate
- Bloom
- Pale to medium blue (occasionally lavender-blue)., Mainly late winter through spring, with scattered bloom at other times.
- Cold hardiness
- Cold-hardy to about 15-20°F (USDA zones 8-11); among the more frost-tolerant desert groundcovers, hardy throughout the Tucson basin.
- Soil
- Demands excellent drainage; thrives in lean, rocky, sandy, and alkaline native desert soils. Prone to root rot in heavy or poorly drained, overwatered soils.
- Native range
- Mediterranean region (the species); a prostrate cultivar widely grown in the Southwest, not native to the Sonoran Desert.
- Best used as
- Groundcover, Spilling over walls, raised beds, and containers, Slope and bank cover, Culinary herb (leaves), Erosion control, Xeriscape plantings
- Wildlife
- Aromatic blue flowers attract bees and other pollinators; deer- and rabbit-resistant due to fragrant oils.
- Toxicity
- Non-toxic; the foliage is the familiar culinary rosemary and is safe for people and pets. Large medicinal quantities of the essential oil can be problematic, but landscape exposure is harmless.
How to grow Trailing Rosemary in Tucson & the low desert
Watering
Very drought-tolerant once established — deep soak every 2-3 weeks in summer is plenty; minimal water in winter. Overwatering and poor drainage are the main causes of decline.
Fertilizer & nutrients
Low requirements; generally needs no fertilizer in reasonable soil. A light spring feeding is optional. Avoid overfeeding, which causes weak, floppy growth.
Pruning & care
Tip-prune lightly to shape and keep dense; avoid cutting into old leafless wood, which resprouts poorly. Trim trailing stems to control spread over walls and edges.
Notes
Evergreen, aromatic, low-trailing form of culinary rosemary that cascades attractively over walls and slopes. Tough, fragrant, and very heat- and drought-tolerant in Tucson; dual-purpose as ornamental groundcover and kitchen herb. Botanical name recently reclassified from Rosmarinus officinalis to Salvia rosmarinus. Good drainage is the key to long-term success.
Sources: University of Arizona Cooperative Extension; AMWUA 'Landscape Plants for the Arizona Desert'; Arizona-Sonora Desert Museum; Tucson Botanical Gardens