Ornamental · Asteraceae
Yarrow
Achillea millefolium
Drop it into full sun and poor, dry soil, then stand back and let yarrow flower all summer.
Full sun
USDA 3–9
1–3 ft · 0.3–0.9 m
Overview
Yarrow is one of the most rewarding tough flowers you can grow. It launches flat clusters of bloom above soft, fern-like foliage that smells sharp the second you crush it, and it pulls in butterflies and other pollinators from early summer into fall. Once it roots in, it powers through heat, drought, and poor soil that would flatten fussier plants.
This is a hardy perennial for zones 3 to 9, so it dies back each winter and comes charging back on its own every spring. The wild species runs cream to white, and the named cultivars break out into red, rose, gold, and salmon. Most hit 1 to 3 feet (30 to 91 cm) tall and spread about as wide.
The one thing to plan for is its appetite for ground: yarrow loves to wander. It runs underground on rhizomes and self-sows freely, so a neat clump can spread into a lively patch in a season or two. Give it room, divide it now and then, and that runaway vigor becomes your best tool for filling a bed fast.
Care
The short version: full sun and lean, dry, well-drained soil. Water it sparingly, skip the fertilizer, and divide the clump every few years to keep it vigorous and in bounds.
Light
Give yarrow full sun, six hours a day or more, and it grows sturdy and flowers its heart out. It will take a little afternoon shade, but the stems stretch and flop in anything dimmer, and the blooms thin out.
Water
This is a drought-tough powerhouse that wants to dry out between drinks. Water young plants until they root, then back way off, because soggy soil rots the crown in a hurry. Once established, it usually cruises along on rainfall alone.
Soil
Lean, well-drained ground is the whole secret. Loam, sand, even poor or alkaline soil all suit it, and a pH anywhere from 6.0 to 8.0 works fine. Rich soil just pumps out weak, floppy stems, so resist the urge to improve it.
Humidity
Outdoor humidity is a non-issue, so there is no level to chase. What counts is air moving through the plant, since still, damp air is what fires up powdery mildew and rust.
Feeding
Feed it almost nothing. Yarrow flowers hardest and lives longest in nutrient-poor soil, and a hit of fertilizer just hands you lush, weak growth that flops. Skip it unless your ground is truly bankrupt.
Pruning
Deadhead the spent flowers through the season to stretch the bloom and rein in the self-seeding. Trim sprawling stems as they show up, then shear the whole plant once flowering winds down to keep it crisp.
Size & spacing
Plants shoot to 1 to 3 feet (30 to 91 cm) tall and spread about as wide. Set them 12 to 18 inches (30 to 45 cm) apart so air rips through and the clumps do not smother each other.
When to plant
Yarrow rides the seasons beautifully. Start seed indoors in late winter or sow it outside in spring, drop the young plants out once frost has passed, and those flat flower heads keep the show rolling 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 yarrow problem comes down to one thing: treating it like a thirsty, hungry plant. Too much water, too much shade, or soil that is too rich brings on the rot, mildew, and flopping below. Spot the early signs and the fix is almost always less, not more.
Plants caving in at the base in wet ground
A plant that goes soft at the base has root and crown rot, and it traces straight back to waterlogged soil, not to some disease you can spray off. Yarrow thrives on lean, dry ground, so it throws in the towel wherever water sits. Get it into a bright, fast-draining spot, cut the extra watering the moment it roots, and slice away the mushy crowns so you can divide the strong outer growth and bring it roaring back.
Fix:
- Move or replant in a well-drained, full-sun site
- Stop supplemental watering once established
- Remove rotted crowns and divide healthy outer growth
White powder creeping over the leaves
That dusty white layer is powdery mildew, a fungus that pounces when the air turns damp and the plants pack in too tight. It almost never takes yarrow down, but it does knock the shine off the foliage. Thin the clump to get air whipping through, aim your water at the roots, and keep the plant blazing in full sun with quick drainage, and it snaps right back.
Fix:
- Improve air circulation by thinning and proper spacing
- Avoid overhead watering
- Site in full sun with good drainage
Bloom stems toppling into a tangled mat
Stems that keel over under their flower heads are lodging, and it usually means the soil is too rich or the corner too shady and wet. Grow yarrow lean and hard, in full sun on dry ground, and watch those stems shoot up strong and stay there. Shear it back once the flowers finish and split the crowded clumps, and it rebounds tight, compact, and ready to go again.
Fix:
- Grow in full sun and lean, dry soil for sturdier, more compact growth
- Cut back or shear after flowering
- Divide crowded clumps
Orange pustules speckling the foliage
Those raised orange specks are rust, a fungus that grabs hold when the leaves stay wet for long stretches. Snap off the infected foliage and bag it fast so the spores cannot jump to fresh growth. Then throw the plant open for airflow, keep the leaves dry, and hold it out in full sun with sharp drainage, and it shrugs the whole thing off.
Fix:
- Remove and dispose of infected foliage
- Improve air circulation and avoid wetting foliage
- Maintain full sun and good drainage
Toxicity
Around animals yarrow is a mild caution, not a serious poison. The leaves and flowers carry alkaloids and volatile oils that can upset a stomach and irritate skin, so keep grazing pets and curious nibblers away from it. People have long used 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 grabs a bite of yarrow tends to drool and go queasy, sometimes with vomiting or loose stools. Chalk it up as a mild caution rather than a real scare, though the sap can also fire up the skin where it lands.
Dogs Mild
Dogs that chew the leaves usually drool, throw up, or get diarrhea, and a few go off their food and turn dull. Keep it filed as a mild caution, since most dogs shake it off without any help.
Horses Mild
A horse that grazes yarrow might drool, scour, or show a bit of colic, especially after a hearty mouthful. The reaction stays at the mild end, though the volatile oils can leave the skin tender.
Rabbits Caution
The alkaloids and oils that rattle other animals make yarrow a bad bet for rabbits and their touchy guts. Flag it as a caution and keep it clear out of the hutch.
Livestock Caution
Cattle, sheep, and goats mostly steer around yarrow for its bitter kick, but a hungry animal that piles in can catch the same stomach upset. Worth a caution where the pasture runs thin.
Birds Caution
There is no good reason to hand yarrow to pet or backyard birds, and the achilleine it packs makes it a caution rather than a treat. Keep cut stems and seed heads well out of their reach.
People Caution
People have leaned on yarrow as a folk remedy for ages, but it is no salad green, and handling it can leave sensitive skin red and itchy. Pull on gloves before you cut it, 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 runs cream to white, so most growers grab a named cultivar with brighter color or a tidier habit. Here are a few well worth chasing down.
Paprika
A spreading, mat-forming yarrow packed with dusty-red flowers and yellow eyes that fade to pink and creamy yellow, though it sprawls and lodges more than most.
New Vintage Rose
A compact rose-pink pick bred to stand up straighter and hold a tidier shape than the free-running wild species.
Strawberry Seduction
A knockout with deep strawberry-red blooms and yellow centers that mellow into softer shades as the season rolls on.
How to propagate
Yarrow multiplies almost too eagerly, whether you split a settled clump or grow it up 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 fastest way to churn out more yarrow, and it reins the plant in at the same time. Dig up a settled clump in spring or fall every 2 to 3 years, break off the vigorous outer growth, and plant the pieces 12 to 18 inches (30 to 45 cm) apart. They dig in and take off 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 is a blast too. Fire it up indoors 6 to 8 weeks before your last frost, or scatter it straight outdoors in spring, and it bolts up fast to flower in its first or second year. It self-seeds with real gusto, so deadhead the spent blooms if you would rather not chase down a crowd of volunteers.
Myths
Yarrow needs rich soil and frequent watering and feeding to thrive.
Flip that on its head. Yarrow throws its best flowers in lean, dry, well-drained ground under full sun, and the more you spoil it, the floppier and shorter-lived it turns. Baby it and you lose it, since wet, rich soil breeds the root rot that finishes the plant.
Yarrow is a tidy clump that stays where you plant it.
Not a chance, and that is half the fun. The wild species charges out in every direction on rhizomes and self-sows freely, so one plant can fill a whole patch in a season or two. Divide it and deadhead it to steer that energy, or grab a sterile named cultivar if you want it to hold its ground.