Gardening
in Tucson, Phoenix,
Arizona and California

Gardening in Tucson, Phoenix, Arizona and California

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Growing Rosmarinus officinalis: Rosemary
Aka: Salvia rosmarinus

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Description
Form: Shrub.
Lifespan: Averaging 10 years, these shrubs may live up to 20 years in desert climates when neglected.
Leaf retention: Evergreen.
Growth rate: Slow to moderate.
Mature Size: 1-6' high and wide depending on cultivar. Shape depends on cultivar and can be round to oval to prostrate.
Flowers: Very small, usually pale blue or sometimes white, clustered.
Bloom: Mid winter into spring. Sporadic blooming may occur in summer and fall with rain.
Fruit: A small, dried, brown nutlet containing one seed.
Leaves: Short, narrow, green above and whitish below, aromatic when touched.
Stems: Woody, no thorns.
Roots: This plant forms a deep taproot, making transplant difficult once it is established.
Wildlife: The flowers attract large numbers of bees. The scent of the leaves repels some insects, including cabbage moths, flies and mosquitos. Rosemary is avoided by rabbits and most other browsing animals.
Toxic / Danger: No. However, if this plant or its extracts are consumed in very large quantities, it may cause illness.
Origin: Mediterranean.

Cultivation and Uses
USDA hardiness zones: 7-11.
Heat tolerant: Yes.
Drought tolerant: Yes.
Sun: Full sun.
Planting: Locate this plant in full, all day sun in well-draining soil. It may be planted next to other xeric plants. Rosemary can also be grown in containers with drainage holes in the bottom and no saucer. Unless in a pot, it should be kept away from plants which need frequent water, such as mint, basil, and tomatoes. It will also compete with tomatoes and chilies for nutrients.
Soil: Well drained, dry, low in organic content. This plant tolerates many soil types except clay and is salt tolerant. Slightly acidic soil is preferred but not required. Fertilizer is unnecessary and may shorten the lifespan of the plant. Rosemary is prone to root rot in poorly draining soil.
Water after becoming established: Monthly to never. This plant can go unwatered in its second year, assuming that rain occurs at least once every month or two. With age, it does best on sparse rainfall alone and can go without water for many months.
Mulch: Never. The soil should dry quickly after rain.
First Year Care: In desert conditions, this plant needs to be watered two or three times a week for the first two weeks, then weekly for one month, diminishing to once a month by winter. Some gardeners stop watering after the first two months and let monthly summer rains take over.
Prune: Pruning is unnecessary in the garden. Rosemary can be pruned to any shape (topiary), or snipped for use as a kitchen herb as needed. It blooms automatically without pruning on year-old wood. Blooms increase with age.
Neglect is the best way to maintain this plant. After it is established, it does better without any maintenance except admiring glances.
Litter: Low to none.
Propagation: Rosemary is usually propagated by cuttings. Older stems have nodes that will grow roots where they touch ground. The seed has very low viability, 1-5%.
Pests: Over watered plants are prone to aphids, whiteflies, and the like. Stop watering this plant after its first year in the ground!
Uses: Culinary herb, ornamental, bee garden, erosion control, insect repellent.

Comments
This plant is a member of the Mint family (Lamiaceae). Salvia rosmarinus is a synonym. That name is contentious, with many researchers favoring Salvia rosmarinus as the accepted name, and Rosmarinus officinalis as the synonym.

The best way to shorten the lifespan of this plant is to plant it in poorly-draining soil, fertilize it, or water it more than once a month after it is established. Neglect is the best maintenance tool after the first year in the ground.



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Latest update: April, 2022

The multi-lobed flowers make a great bee landing pad. The filaments and style are curved on this cultivar to deposit and accept pollen from the bee's back.


Two brown nutlets, the result of previous bee visits, can be seen at top left.


A three year old Rosemary plant, near the end of its winter-spring bloom, still attracting many bees.