Upright and trailing rosemary in Hesperia, Victorville and Apple Valley: cold, water, soil and care.
Get a Free Planting PlanRosemary grows well in the High Desert when it gets full sun, fast-draining soil and a light hand with the hose. The University of Arizona rates it hardy to about 10F once it has hardened off in fall, which covers a normal Victor Valley winter (zone 8b, 15 to 20F on the coldest nights) but leaves it exposed in cold pockets and record freezes. Both the upright shrub and the low prostrate (trailing) form do the job here; pick by the space you need to fill.
Top photo: Photo: Petar43, CC BY-SA 3.0, via Wikimedia Commons
Shrub or groundcover · Salvia rosmarinus (formerly Rosmarinus officinalis) · Also called Rosemary Plant, Rosemary Bush, Prostrate Rosemary, Trailing Rosemary · Native to the Mediterranean region
| Rosemary at a glance in the High Desert | |
|---|---|
| Type and size at maturity | Evergreen shrub. Upright forms grow 3 to 6 ft tall; prostrate (trailing) forms stay 1 to 2 ft tall and spread wider [3] |
| Growth rate | Medium [4] |
| Water once established | Moderate (WUCOLS IV, Region 5: M for both upright and trailing rosemary) [2] |
| Sun | Full sun to partial shade [1] |
| Cold hardiness | About 10F if it hardens off slowly in fall (University of Arizona); USDA zones 8a to 10b (NC State). ‘Arp’ is rated hardier, to about zone 6. Borderline on the coldest High Desert nights [3] |
| Soil | Well-drained. Handles sandy, loamy and rocky soil; does poorly in clay [4] |
| Bloom | Light blue flowers in winter and spring [1] |
| Evergreen or deciduous | Evergreen, aromatic foliage [1] |
| Pets | Non-toxic to dogs, cats and horses (ASPCA) [5] |
| Wildlife | Attracts bees and birds [1] |
| Rabbits and deer | Deer resistant; the strong scent usually keeps browsing animals away [4] |
| Where it fits | Trailing forms over walls, slopes and rock gardens; upright forms as an informal hedge [3] |
Cold is the one thing to watch. University of Arizona Extension says rosemary is hardy to 10F “as long as it has some time to slowly harden off in the fall,” and NC State lists it for USDA zones 8a through 10b. Most of Hesperia, Victorville and Apple Valley sit in zone 8b, where the average coldest night lands between 15 and 20F. That is inside rosemary’s range. The problem nights are the outliers: NOAA records for Victorville go down near 0F, and low spots on a lot collect colder air than the weather station sees.
Summer heat is not the issue. The Victor Valley averages around 97F in July, and rosemary comes from dry Mediterranean hillsides. Wind is more of a nuisance than a threat for an established plant, but young plants set out in March or April can dry out fast in the spring gusts, so check the soil more often the first season. See the High Desert frost dates and growing zones guide for local freeze numbers.
Nurseries sell two growth forms, and they fill very different spots. University of Arizona describes the prostrate form at 1 to 2 feet tall and the upright form at 3 to 6 feet. The SB County Guide to High Desert Landscaping, written with UC Cooperative Extension, lists rosemary as a groundcover about 2 feet high spreading 4 feet or more, and notes that taller varieties reach 6 feet or more.
WUCOLS IV rates both forms Moderate for Region 5, the High and Intermediate Desert, so they take the same drip schedule. In a rockscape, trailing rosemary over a boulder or a low retaining wall softens the rock without much upkeep. Upright plants read better as a background row behind lower plants like red yucca.
Drainage decides whether rosemary lives. NC State says it tolerates most soils except clay, and the most common cause of decline is overwatering. High Desert soils are usually sandy and alkaline, which suits it, but a layer of caliche under the planting hole can hold water like a bathtub. Dig down and punch through any hardpan you hit, or plant on a slight mound. The High Desert soils guide covers how to spot and break caliche.
Plant in fall or in spring after the last frost. Victorville’s median last freeze is around March 18, and one year in ten it runs past April 12. Small 4-inch pots establish fast and cost less.
For water, University of Arizona suggests every 3 to 5 days while the plant establishes, then cutting back once the roots spread. It notes that May and June are the most critical months, and that plants in native soil usually need no fertilizer. With only about 5.57 inches of rain a year in Victorville, plan on drip for the life of the plant, just not much of it. Water deeply and let the soil dry between cycles. The High Desert irrigation guide explains emitter sizing and run times.
Most rosemary that dies in a desert yard is watered to death, not dried out. NC State lists root rot and botrytis as the common diseases and calls overwatering “the common cause of plant decline or death.” University of Arizona adds that heavily irrigated plants turn woody. Signs of too much water on desert plants, per University of Arizona’s Care of Desert-Adapted Plants, include wilted shoot tips, soft or smelly tissue and algae or mushrooms on the soil.
Rosemary that makes it through the first year usually lives a long time, according to University of Arizona.
Plant after the last frost (median March 18 in Victorville). Trim any cold-damaged tips once new growth shows. Keep young plants watered through spring wind.
May and June are the most critical months for irrigation (University of Arizona). Water deeply and let the soil dry between cycles; do not add extra water just because it is hot.
A good planting window. Taper water and skip fertilizer so the plant can harden off before the first freeze.
Water only occasionally in dry spells; evergreen plants need infrequent, deep winter irrigation (University of Arizona). Expect some tip burn after nights in the low teens.
Yes, once established. WUCOLS rates it Moderate for the High and Intermediate Desert, so it still needs occasional deep drip water here. Too much water is a bigger risk than too little.
University of Arizona rates it hardy to about 10F if it hardens off slowly in fall. The variety ‘Arp’ takes much colder weather. Record lows in Victorville go below that, so plant it in a warm spot.
Yes. The ASPCA lists rosemary as non-toxic to dogs, cats and horses.
They are the same low, spreading form sold under different names. It grows 1 to 2 feet tall and spills over walls and slopes, while upright rosemary grows 3 to 6 feet tall.
Fall, or spring after the last frost. Victorville’s median last freeze is around March 18. Plant in well-drained soil and water every few days until it roots in.
We checked every number on this page against the public sources below. If a rule or date changes, the agency page is the final word.
Monarch designs and installs rockscape, drip irrigation and drought-tolerant plantings across the High Desert. We will check sun, wind and soil on your lot and tell you where a plant will do well and where it will struggle.
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