Ornamental · Asteraceae
Yarrow
Achillea millefolium
Set it in full sun and poor, dry soil, then let it be, and yarrow carries a border all summer.
Full sun
USDA 3–9
1–3 ft · 0.3–0.9 m
Overview
Yarrow brings an easy, meadow-inspired mood to a sunny garden. Flat clusters of bloom hover over soft, fern-like foliage that scents the air when brushed in passing, and the flowers keep company with butterflies and other pollinators from early summer into fall. Once it takes to a spot, it holds up through heat, dry spells, and thin soil, asking almost nothing of a busy weekend.
This is a hardy perennial for zones 3 to 9, a plant that retreats each winter and returns to the border on its own every spring. The wild form reads cream to white for a soft, naturalistic look, while named cultivars open the palette to red, rose, gold, and salmon for a warmer scheme. Most settle between 1 to 3 feet (30 to 91 cm) tall with a matching spread, a comfortable mid-border height.
The one habit to plan around is its wandering nature. Yarrow drifts on underground runners and seeds itself into new ground, so a neat clump can loosen into a broad sweep if the border goes unwatched. Give it space, divide it now and then, and that easy spread becomes a design asset for filling a sunny bed.
Care
The short version: full sun and lean, dry, well-drained soil suit it best. Water it lightly, leave off the fertilizer, and divide the clump every few years to keep the planting vigorous and in bounds.
Light
Give yarrow full sun, six hours a day or more, and it stands sturdy and flowers freely, the look a sunny border wants. It will accept a little afternoon shade, but the stems stretch and lean in anything dimmer and the flowering thins.
Water
This is a drought-easy plant that prefers to dry out between drinks. Water young plants until they root, then ease right off, because soggy soil is the quickest route to a rotted crown. Once settled, it usually lives on rainfall alone.
Soil
Lean, well-drained ground is the whole secret to keeping it handsome. Loam, sand, even poor or alkaline soil all suit it, across a pH of 6.0 to 8.0. Rich soil only breeds weak, floppy stems, so leave the border unimproved.
Humidity
Outdoor humidity asks nothing of you, so there is no level to manage. What counts is air moving through the planting, since still, damp air is what invites powdery mildew and rust.
Feeding
Feed it almost nothing and it thanks you. Yarrow flowers best and lasts longest in nutrient-poor soil, and fertilizer only brings lush, weak growth that flops in the bed. Skip it unless the ground is truly spent.
Pruning
Deadhead the spent flowers through the season to stretch the bloom and quiet the self-seeding. Trim sprawling stems as they appear, then shear the whole clump once flowering fades to keep the planting composed.
Size & spacing
Plants reach 1 to 3 feet (30 to 91 cm) tall with a matching spread, an easy mid-border scale. Set them 12 to 18 inches (30 to 45 cm) apart so air moves through and the clumps read as a clean sweep rather than a crush.
When to plant
Yarrow keeps a relaxed calendar. Start seed indoors in late winter or sow it outdoors in spring, set young plants into the bed once frost has passed, and the flat flower heads carry the border from June into September.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Start seed indoors 6 to 8 weeks before the last spring frost.
- Plant: Transplant after danger of frost has passed in spring, spacing plants 12 to 18 in apart.
- Harvest: Blooms June to September, with flat-topped flower clusters from early summer into fall.
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Nearly every trouble with yarrow traces back to one thing: treating a lean-country plant as though it wanted pampering. Too much water, too much shade, or soil that is too rich brings on the rot, mildew, and flopping below. Read the early signs and the answer is almost always to do less.
A planting failing at the base in wet ground
When a planting sinks and softens at the base, the culprit is root and crown rot, a reaction to soil that holds water rather than a disease to be treated. Yarrow belongs in a lean, sun-baked border, not a low, thirsty corner of the garden. Resettle it in a bright, sharply drained bed, taper off the watering once it takes, and clear the spoiled crowns before dividing the healthy edges for a fresh start.
Fix:
- Move or replant in a well-drained, full-sun site
- Stop supplemental watering once established
- Remove rotted crowns and divide healthy outer growth
A chalky white cast dulling the foliage
A soft white haze across the leaves is powdery mildew, a fungus that arrives when the air sits still and damp and the border grows too full. It rarely threatens the plant, but it takes the polish off an otherwise handsome clump. Open the planting for a little breathing space, direct water to the roots, and keep it in full sun where the ground drains cleanly.
Fix:
- Improve air circulation by thinning and proper spacing
- Avoid overhead watering
- Site in full sun with good drainage
Bloom stems slumping into a loose tangle
Stems that lean and slump under their flower heads are lodging, the usual reward for soil that is too generous or a corner that is too shaded and damp. Grow yarrow a little tougher, in full sun on lean, dry ground, and it carries itself with far more poise. A shear after the flowers pass and a division of the crowded clumps keep the planting trim and upright for the season ahead.
Fix:
- Grow in full sun and lean, dry soil for sturdier, more compact growth
- Cut back or shear after flowering
- Divide crowded clumps
Rusty flecks marking the foliage
Raised orange to brown flecks along the leaves are rust, a fungus that settles in wherever foliage stays wet for long stretches. Clip away the marked leaves and discard them so the spores find no foothold on the rest of the planting. Give the clump more air, keep the leaves dry, and hold it in full sun with clean drainage to keep it looking its best.
Fix:
- Remove and dispose of infected foliage
- Improve air circulation and avoid wetting foliage
- Maintain full sun and good drainage
Toxicity
Yarrow is a mild caution around animals rather than a serious poison. Its leaves and flowers hold alkaloids and volatile oils that can upset a stomach and irritate skin, so place it thoughtfully and keep grazing pets and curious nibblers away. People have long turned to it as a folk remedy, but it is not food, and the sap leaves some hands red and itchy.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A cat that samples yarrow tends to drool and turn queasy, with a little vomiting or a loose stool or two. The plant reads as a mild caution rather than a real hazard, though the sap can leave the skin irritated where it lands.
Dogs Mild
Dogs that chew the leaves usually drool, bring their food back up, or run loose, and the occasional one loses interest in dinner and seems subdued. Keep it a mild caution, since most settle again without any fuss.
Horses Mild
A horse grazing yarrow may drool, scour, or show a hint of colic, more so after a generous mouthful. The effect stays at the mild end, though the volatile oils can leave the skin a touch tender.
Rabbits Caution
The alkaloids and oils that unsettle other animals make yarrow a poor companion for rabbits and their delicate digestion. Treat it as a caution and keep it well clear of the hutch.
Livestock Caution
Cattle, sheep, and goats usually pass yarrow by for its bitterness, yet a hungry animal grazing it in quantity can pick up the same upset. It is worth a caution where the pasture runs thin.
Birds Caution
There is little sense in offering yarrow to pet or backyard birds, and the achilleine it carries makes it a caution rather than a treat. Keep cut stems and seed heads out of their reach.
People Caution
Yarrow has a long life in the folk medicine cabinet, but it is no salad leaf, and handling it can leave sensitive skin red and itchy. Slip on gloves for cutting, and treat any eating of the plant as a caution.
Sesquiterpene lactones and volatile oils can cause contact dermatitis in sensitive people; consider gloves when handling or cutting plants.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
The wild species spreads hard and reads only cream to white, so most gardeners reach for a named cultivar with richer color or a tidier shape to suit a designed border. A few are worth knowing.
Paprika
A low, mat-forming yarrow whose dusty-red flowers with yellow eyes soften to pink and creamy yellow with age, best given room since it sprawls and lodges more than most.
New Vintage Rose
A refined, compact rose-pink selection bred to stand upright and hold a tidier shape than the wild species.
Strawberry Seduction
A striking choice carrying deep strawberry-red blooms with yellow centers that mellow to gentler shades across the season.
How to propagate
Yarrow multiplies with ease, whether you divide a settled clump or raise a fresh drift from seed.
DivisionEasy
Divide established clumps in spring or fall, every 2 to 3 years. · Divisions root and re-establish within one growing season.
Division is the graceful way to multiply yarrow and to keep a border in balance at the same time. Lift a settled clump in spring or fall every 2 to 3 years, part the vigorous outer growth from the tired center, and set the pieces 12 to 18 inches (30 to 45 cm) apart. They root in and find their place within a single growing season.
SeedEasy
Sow indoors 6 to 8 weeks before last frost or direct sow in spring. · Germinates readily; flowers the first or second season.
Seed offers an easy path to a broad sweep of bloom. Sow indoors 6 to 8 weeks before your last frost, or scatter it straight into the bed in spring, and it rises quickly to flower in its first or second year. It self-seeds with real freedom, so deadhead the spent heads whenever a composed, uncrowded planting is the goal.
Myths
Yarrow needs rich soil and frequent watering and feeding to thrive.
The reverse is true, and it makes yarrow a gift for a low-maintenance border. It looks its best in lean, dry, well-drained ground under full sun, and every extra kindness leaves it floppier and shorter-lived. Restraint is the whole art here, since rich, wet soil invites the root rot that ends the planting.
Yarrow is a tidy clump that stays where you plant it.
In truth it is a roamer. It travels outward on rhizomes and sows itself freely, so a single clump can widen into a drift within a season or two. A regular division and deadhead keeps the picture composed, or choose a sterile named cultivar when a border wants a plant that stays exactly where it is placed.