Many California natives are exclusively indigenous to California or the West Coast, but Achillea millefolium has broadened its reach to most of the Northern Hemisphere. This plant gets around! Known as common yarrow, its fine-textured leaves appear as delicate as fern fronds, but the plant is hardier than one thinks. Drought resistant, it spreads from underground stems and reseeds; according to several souces, this herbaceous perennial could be considered invasive. Common yarrow and its cultivars have showy flowers ranging from white to shades of yellow, orange, pink, and red. While attractive in the nurseries, especially when in full bloom, the plant behaves differently in the landscape. This difference should be well understood before specifying it on a project.
Primarily, A. millefolium does not remain a compact little specimen as it becomes established. Rather, those underground stems mentioned earlier will spread the plant in all directions, popping up close and far, expanding its territory. This means that the species can look great in a container for awhile, but eventually it will show its preference to run free. This may sound ominous, but common yarrow is not bamboo. When not in bloom, the plant itself is only a few inches tall to a foot (it can reach 3' when in bloom), and its spreading is irregular, forming both erect clumps and meandering mats in the landscape. Other plants can grow through it, so it may appear to be weedy and unkempt. However, all of this means common yarrow lends itself to a unique landscape use, which is as part of a meadow mix. Blended with other native species, meadows are the new answer to replacing useless lawns (as opposed to useful play, event, and sport lawns). These designed meadows offer opportunities to created species diversity, habitat, and floral tapestries in the landscape. Did I mention common yarrow flowers are showy? What's not to love?
Its look in late autumn, that's what's not to love for those who demand green all year round. A. millefolium and its perennial kind will go dormant or look shabby as early as fall (if water is an issue). Winter may also be barren, or it will come alive when winter rains occur. With the right combination, winter blooming species can be added to a meadow thus creating more active designs, so it is up to the designer to do their research. Undoubtedly, there are other outstanding examples, but the McConnell Arboretum & Botanical Garden at Turtle Bay Exploration Park, Redding, has a wonderfully designed meadow that should be seen through the seasons to understand how meadows perform. Or wander through Mother Nature's meadows and see if you can spot common yarrow in bloom.
Other cultivars:
'Florachye1' Milly Rock™ (yellow)
'Paprika' (Red)
'Sonoma Coast' (white)
facts
Botanical Name: Achillea millefolium
Achillea: Honoree, mythological warrior Achilles, who used yarrow extract to heel wounds.
Millefoium: Having many leaves (or leaflets). For this species, the leaves have a fine texture.
Common Name: Common yarrow; milfoil
Family Name: Asteraceae
Origin: Native; Northern Hemisphere
design considerations
Positioning: Foreground, under foot (infrequently), allowed to move freely
Garden Themes: Native/Mediterranean/dry, cottage/informal, pollinator, wildflower, rain
Uses: Meadow/prairie, habitat, container, cut flower (fresh or dried), mass, border, edging, ground cover, lawn substitute (with limitations), green stormwater infrastructure (elevated slopes and uplands only)
identifying characteristics
Type: Herbaceous perennial
Form: Mat, basal, erect clump
Texture: Fine
Size: 12" tall and spreading, but to 3' tall when in bloom
Outstanding Feature(s): Flower
Stem: Gray, gray-green, silver; underground rhizomes
Leaf:
Type: Pinnately compound (tetraploid, with leaflets arranged three dimensionally)
Arrangement: Alternate
Shape: Oblong
Margin: Entire
Color: Gray-green, light green, silver
Surface: Feathery
Flower: Summer to Autumn. Showy, dense compound corymbs, white to off-white (cultivars vary from white to shades of yellow, orange, pink, or red)
Fruit: Autumn. Tiny achenes, readily viable
cultural requirements, tolerances & problems
Sunset Zones: A1-A3; 1-24
USDA Zones: 3-9
Light: Full sun
WUCOLS SF Bay Area Hydro Zone: Low (non-cultivar species; Medium for cultivars)
Soil:
Texture: Sand, loam, clay
Moisture Retention: Well-drained
pH: Highly acidic to highly alkaline
Tolerances: Drought
Problems: May become invasive
Branch Strength: N/A
Insects:
Disease: Stem rot, powdery mildew, rust,
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Calscape. "Common Yarrow." California Native Plant Society, Sacramento. Accessed on August 17, 2021, from https://calscape.org/Achillea-millefolium-(Common-Yarrow).
Fire Effects Database System. "Achillea millefolium." United States Department of Agriculture, Washington D.C. Accessed on August 17, 2021, from https://www.fs.fed.us/database/feis/plants/forb/achmil/all.html.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Achillea millefolium." Missouri Botanical Garden, St. Louis. Accessed on August 17, 2021, from http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=277129.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on August 17, 2021, from https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.
Photos:
Leaf Detail: "Achillea millefolium 3" by Thayne Tuason is licensed under Wikimedia Commons.
Single plant: "Yarrow Achillea millefolium plant" by Dcrjsr is licensed under Wikimedia Commons.
Common yarrow in meadow mix by TELCS.
Feature photo and nursery plants - Achillea millefolium 'Sonoma Coast' by TELCS.
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