The first time I came across Westringia fruiticosa, or coast rosemary, was when I used to work for a wholesale nursery in Sonoma County. My discovery was not in the nursery, however. A retirement community across the highway had planted this low maintenance species at the main entrance, creating a long, oblong hedge down the middle of the street. It caught my eye, which happens often to this plant geek. I think I marveled at its informal and soft form, a contrast to the community's affection for topiary balls and flying saucers. Whomever made the call for something that blended so well into the natural landscape earned a gold star from moi! That was a while ago. Today and with irony, the median is planted with intermittent spots of common rosemary and a row of all too ubiquitous crape myrtles. Pretty, but these two species can be found at every other commercial landscape. Gone but not forgotten are the beloved Westringia.
With the sun in one's eyes and a bit of squinting, this native Australian coast rosemary can be easily confused with the Mediterranean species popularized among cooks. Both are drought tolerant, have small gray to gray-green leaves, and tiny flowers, but that might be as far as the comparison can go. One obvious difference is the use and fragrance of culinary rosemary, which cannot be said for coast rosemary. So, do not try it as part of a dry rub for your BBQ! W. fruiticosa has white flowers, whereas the herb, Rosmarinus officinalis, has pale blue flowers. Of course, there are always exceptions: W.f. 'Wynyabbie Gem' has light lavender flowers, lending to its mistaken identity, and R.o. 'Lady in White', having white flowers, will add confusion to the untrained eye. Interestingly, both Westringia and Rosmarinus belong to the mint family, Lamiaceae, which are known for their resistance to deer.
If their color and texture can confuse our understanding of their unique qualities, form can provide a little more distinction. Most R. officinalis will have erect stems and a somewhat irregular form; ground cover species are the exception that have a tendency to grow more prostrate, hence the name R. officinalis prostratus. By contrast, W. fruiticosa is a naturally rounded, woody shrub, lending itself to its symmetrical form with minimal pruning...a good choice where maintenance is a concern.
Landscape Architect, Jeff Wortham, provides this solid overview, even if the video quality is a little low.
Wortham continues to present good pruning practices that does not require machinery.
Cultivars
'Wynayabbie Gem': Pale lavender flowers
'Morning Light': More compact with leaves edged in white
'NFL25': Also known as W.f. Mundi, could be used similar to prostrate rosemary, growing to 2' tall with a 4'-6' spread and white flowers.
'Smokey': Similar in size but has a tendency to be more upright than round.
'WES04': Also known as W.f. Grey Box or dwarf coast rosemary. Grey Box suggests a reference to its compact form resembling dwarf boxwood, colloquially known as "box." About 2' x 2' with white flowers.
facts
Botanical Name: Westringia fruiticosa
Westringia: Honoree, physician & botanist, Johan Petrus Westring
Fruiticosa: Shrubby or bushy
Common Name: Coast rosemary (this is not a rosemary)
Family Name: Lamiaceae
Origin: Australia
design considerations
Positioning: Middle ground to background
Garden Themes: Coastal, Mediterranean, Drought, Commercial
Uses: Formal or informal hedge, border, mass, foundation, slopes, accent
identifying characteristics
Type: Evergreen shrub
Form: Dense mound
Texture: Fine
Size: 6' tall x 10' wide (usually clipped as smaller hedge or mound)
Outstanding Feature(s): Flower, foliage
Stem: Light gray to tan
Leaf:
Type: Simple
Arrangement: Whorls
Shape: Lanceolate
Margin: Entire
Color: Dark gray-green above, white underside
Surface: Glabrous and hairy above, hairy petiole and underside
Flower: Spring to all year. Flowers small, single, five petaled, axillary, white or white with purple to brown spots
Fruit: Segmented, woody, brown
cultural requirements, tolerances & problems
Sunset Zones: 8, 9, 14-24
USDA Zones: 8-11
Light: Full Sun
WUCOLS SF Bay Area Hydro Zone: Low
Soil:
Texture: Sand, rocky
Moisture Retention: Well-drained
pH: Alkaline
Tolerances: Deer, drought, coastal wind
Problems:
Branch Strength: Medium
Insects: No observed insects at time of posting.
Disease: Root rot, chlorosis
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Flora & Fauna Web. "Westringia fruticosa (Willd.) Druce." Singapore National Parks. Accessed on February 10, 2023, from https://www.nparks.gov.sg/florafaunaweb/flora/4/8/4897.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on October 20, 2021, from https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.
Waterwise Garden Planner for Southern California. "Coast rosemary." Chino Basin Water Conservation District. Accessed on February 10, 2023, from https://waterwisegardenplanner.org/plants/westringia-fruticosa/.
Photos:
Flowers and Foliage: "Westringia Fruticosa" by Georgios Liakopoulos is licensed under Creative Commons - ShareAlike 3.0 Unported (CC BY-SA 3.0).
Flowers Detail: "Westringia fruticosa #1" by James Gaither is licensed under Creative Commons - 2.0 Generic (CC BY 2.0).
Shrub: "Coastal Rosemary (Westringia fruticosa)" by Danielle Langlois is licensed under Creative Commons - ShareAlike 3.0 Unported (CC BY-SA 3.0).