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Scientific: Rosmarinus officinalis (Synonym: Salvia rosmarinus)
Common: rosemary, romero
Family: Labiatae
Origin: Mediterranean region

Taxonomic confusion: Recently, the Royal Horticultural Society (RHS) has proposed that the scientific name of rosemary be changed to Salvia rosmarinus based on molecular phylogenetic research. Thus, Rosmarinus is no longer a genus, but rather is a monophyletic species within the genus Salvia. Though the RHS has adopted this new scientific name, until the Integrated Taxonomic Information System (ITIS) or the WFO Plant List recognize it as the accepted name, I will identify Salvia rosmarinus as a worthy synonym.

Pronounciation: Rose-MAR-i-nus of-fi-ci-NAL-is

Hardiness zones:
Sunset 4-24
USDA 8 (treat as summer annual in cooler zones)-11 (best in semi arid Mediterranean climates).

Landscape Use: Ground cover, rock garden, elevated planters, accent, herb garden, border, informal hedge, even containerized Christmas trees!

Form & Character: Rosemary form depends on varietal phenotype from rigid and upright to graceful, cascading, spreading and prostrate, aromatic, Mediterranean tough, yet refined looking.

Growth Habit: Evergreen, woody, narrowleaf perennial shrub, slow to moderately fast from 2-to 8-feet tall depending on cultivar and soil conditions, watering, fertility, etc. Prostrate forms spread quickly.

Foliage/Texture: Sessile (no petiole), viscid (sticky), linear leaves to 1/2-inch long on a viscid (sticky) stem, dark green above, white pubescent below; medium fine texture.

Flowers & Fruits: Small, axillary, light blue flowers formed in massed clusters; fruits inconspicuous.

Seasonal Color: Light blue flowers in January to March.

Temperature: As a Mediterranean plant that is biologically active when the weather is seasonally cool, rosemary looks much better during winter, and struggles from July to September during the extreme desert summer heat without some protection.

Light: Full sun

Soil: In Phoenix, rosemary MUST have well-drained soil, especially in desert regions during summer. In desert areas, rosemary is generally a poor performer in heavy, flat, poorly drained clay soils and grows best in gravelly and sandy to loam soils. Along the central and southern California coast however, rosemary thrives in heavy clay soils.

Watering: Generally rosemary need only infrequent deep irrigations. In Phoenix, great care should be given to water appropriately during the summer, especially if soil has a high clay content and drains slowly. Why? Because rosemary is a Mediterranean plant that is biologically active during the cooler winter months with a quiescent habit (slow to no growth) during the summer. Because of this rosemary roots are prone to root rot during the summer if soils are frequently irrigated.

Pruning: Depends on use, but in any case never extensively prune rosemary to the point of removing all foliage. If "whacked and chopped", rosemary plants will rarely recover. Prune prostrate forms from underneath removing deadwood. Upright forms can be pruned lightly in many different ways including light shearing into a conical-shaped Christmas tree.

Special pruning note: Solitary upright forms of rosemary make the perfect landscape plant specimen for the 'Horticultural clods of Phoenix' (aka 'Hort clods') to hone their skills.

Propagation: Cuttings in a relatively porous propagation rooting substrate.

Disease and Pests: Spittle bug (looks like spit on a stick) infects succulent stems of plants in spring if the plants are located in spots that recieve modest amounts of shade (causing spindly growth). Root rot if soil poorly drained!

Additional comments: Upright and prostrate forms such as the cultivar 'Tuscan Blue', are used in herb gardens. For landscape use, there are several low growing cultivars. 'Prostratus' is a prostrate cultivar to 8-feet wide by 2- to 3-feet tall. `Irene' on the other hand is a cultivar introduced in 1996 in central California and grows only 12- to 24-inches tall, great as edging plant. For use as a landscape ground cover, plant prostrate rosemary cultivars at 24 to 36 inches on center.

A philosophical moment: What is rosemary? It is said that rosemary got its name from the Virgin Mary. Rosemary is also an old French term for incense. Because Rosemary was easily harvested from the wild in and around ancient Mediterranean cultures (think ancient Roman, Greek, Spartan, and Trojan dudes), it was an incense used by the poor or lower classes as a substitute for the more expensive frankincense or myrrh-based incense of the rich folks. Rosemary extract is rich in numerous compounds that cause biological effects.

The final note: Rosemary flowers strongly attract bees!