One of the best and toughest ground cover plants for arid regions, Trailing Rosemary does well in nutrient-poor and shallow soils. This plant tolerates great heat and blazing sun as well as cold. Dark green leaves grow to 2 inches long and are rich in aromatic oils. The foliage has a pine-like fragrance. Small, pale blue to white flowers appear along its branches from March to May. The low-growing, trailing form makes an ideal ground cover. The upright form makes a nice shrub or hedge. Rosmarinus officinalis 'prostratus' grows to only about 1 foot high and spreads to 5 feet or wider. In addition to making an excellent ground cover, Trailing Rosemary may be planted in rock gardens, retaining walls or containers.
Plant Trailing Rosemary in the fall in low-desert regions. Plant it in the spring in the high elevation zones. Locate plants in full sun. It does best in rocky, alkaline soil but may fail in heavy, clay soils. This plant is quite drought-tolerant, requiring little water once established. In the low deserts, water established trailing rosemary plants every two to three weeks in the summer and once a month in the winter. Rely on rainfall in high elevation zones. It may yellow slightly if kept too dry. Shearing the top encourages the side branches to spread. Take care not to trim trailing rosemary back beyond the last bit of foliage, or it may not to sprout new growth. Under very humid conditions, fungal diseases can affect the foliage. Minimize infection by planting trailing rosemary in full sun, thinning the foliage to allow air circulation, and watering it in the morning, so the foliage dries quickly.