Ornamental · Asteraceae
Yarrow
Achillea millefolium
Pop it in full sun and poor, dry soil, then leave it alone, and yarrow flowers all summer long.
Full sun
USDA 3–9
1–3 ft · 0.3–0.9 m
Overview
Want a flower that is almost impossible to kill? Yarrow is your plant. It holds flat clusters of bloom above soft, fern-like leaves that smell sharp when you crush them, and it brings in butterflies and other pollinators from early summer right into fall. Once it settles in, it laughs off heat, dry spells, and poor soil that would do in fussier plants.
It is a hardy perennial for zones 3 to 9, so it dies back each winter and just comes back on its own every spring. The wild kind runs cream to white, but the named cultivars branch out into red, rose, gold, and salmon. Most of them stay between 1 to 3 feet (30 to 91 cm) tall and spread about the same.
The one thing to keep an eye on? Yarrow likes to wander. It travels around on underground runners and seeds itself, so a neat little clump can turn into a big sprawling patch if you look away too long. Give it some elbow room, divide it every so often, and that wandering habit works in your favor.
Care
The short version: full sun and lean, dry, well-drained soil. Go easy on the water, forget 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 tough and flowers like mad. It will handle a bit of afternoon shade, but any dimmer and the stems stretch out and flop, and you get fewer flowers.
Water
This is a drought-tough plant that likes to dry out between drinks. Water the young ones until they root, then back way off, because soggy soil is the fastest way to rot the crown. Once it is settled, it usually gets by on rain alone.
Soil
Lean, well-drained ground is really the whole trick. Loam, sand, even poor or alkaline soil all work fine, and a pH anywhere from 6.0 to 8.0 is no problem. Rich soil just gives you weak, floppy stems, so do not bother trying to improve it.
Humidity
Outdoor humidity is not something to worry about, so there is no level to fuss over. What actually matters is air moving through the plant, since still, damp air is what kicks off powdery mildew and rust.
Feeding
Feed it basically nothing. Yarrow flowers best and lives longest in nutrient-poor soil, and a shot of fertilizer just gives you lush, weak growth that flops over. Skip it unless your soil is really run down.
Pruning
Deadhead the spent flowers through the season to stretch out the bloom and cut back on self-seeding. Trim any sprawling stems as they pop up, then shear the whole thing once flowering winds down to keep it looking neat.
Size & spacing
Plants get 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 can move around and the clumps do not smother each other.
When to plant
Yarrow just goes with the seasons. Start seed indoors in late winter or sow it outside in spring, set the young plants out once the frost is done, and those flat flower heads will keep the show going 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
Here is the thing: almost every yarrow problem comes back to 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 down below. Catch it early and the fix is usually less, not more.
Base going soft and mushy in wet ground
If a plant turns to mush at the base, that is root and crown rot, and it comes down to soggy soil rather than some bug you can spray away. Yarrow is a lean-and-dry kind of plant, so it just gives up where water hangs around. Move it somewhere sunny that drains well, quit the extra watering once it has settled in, and cut off the slimy crowns before you split the good outer growth to save it.
Fix:
- Move or replant in a well-drained, full-sun site
- Stop supplemental watering once established
- Remove rotted crowns and divide healthy outer growth
Leaves looking dusted with white powder
See a whitish film on the leaves? That is powdery mildew, a fungus that shows up when the air is damp and the plants are jammed together. It hardly ever kills yarrow, but it does make the foliage look a bit worn out. Thin the clump so air can get through, water down at the roots instead of over the top, and keep it in full sun where the soil drains fast.
Fix:
- Improve air circulation by thinning and proper spacing
- Avoid overhead watering
- Site in full sun with good drainage
Stems flopping over into a messy tangle
When the stems keel over under their flower heads, that is lodging, and it usually means the soil is too rich or the spot is too shady and damp. Grow yarrow the tough way, in full sun on lean, dry ground, and you will notice the stems stand up much better. Give it a shear once it finishes blooming and split up any crowded clumps, and the new growth comes back nice and compact.
Fix:
- Grow in full sun and lean, dry soil for sturdier, more compact growth
- Cut back or shear after flowering
- Divide crowded clumps
Little orange spots peppering the foliage
Those raised orange bumps are rust, a fungus that moves in when the leaves stay wet for ages. Pull off the spotted leaves and toss them in the bin so the spores cannot hitch a ride onto healthy growth. Then open the plant up so air moves through, keep the leaves dry, and hang onto that full sun with good drainage.
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 more of a mild caution than a real poison. The leaves and flowers carry alkaloids and volatile oils that can upset a stomach and bug the skin, so keep grazing pets and curious nibblers away from it. And sure, people have used it as a folk remedy forever, but it is not food, and the sap leaves some folks red and itchy.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
If a cat has a nibble, you will probably see some drooling and a queasy tummy, maybe a bit of vomiting or loose stools. It is really just a mild caution and not a scary one, though the skin can get irritated where the sap touches.
Dogs Mild
Dogs that chew the leaves usually drool, throw up, or get diarrhea, and a few go off their dinner and act a little flat. Think of it as a mild caution, since most dogs bounce back on their own.
Horses Mild
A horse that grazes on yarrow might drool, get loose, or show a touch of colic, especially after a big mouthful. It stays on the mild side, but those volatile oils can leave the skin feeling tender.
Rabbits Caution
Yarrow is not a good pick for rabbits, because the same alkaloids and oils that bug other animals hit their delicate tummies pretty hard. Treat it as a caution and keep it out of the hutch.
Livestock Caution
Cattle, sheep, and goats mostly walk right past yarrow since it tastes bitter, but a hungry one that tucks in can end up with the same stomach upset. Worth a caution when the pasture is looking thin.
Birds Caution
There is not much reason to hand yarrow to pet or backyard birds, and the achilleine in it makes it a caution rather than a snack. Keep cut stems and seed heads somewhere they cannot get to.
People Caution
People have used yarrow as a folk remedy forever, but it is not exactly a salad green, and handling it can leave sensitive skin red and itchy. So pop on some gloves before you cut it, and treat eating 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 only comes in cream to white, so most people just grab a named cultivar with brighter color or a neater habit. Here are a few worth a look.
Paprika
This is a low, mat-forming yarrow with dusty-red flowers and yellow eyes that fade to pink and creamy yellow, though it does sprawl and flop more than most.
New Vintage Rose
A tidy, compact rose-pink one that was bred to stand up straighter and behave better than the wild species.
Strawberry Seduction
This one gives you deep strawberry-red blooms with yellow centers that mellow into softer shades as the season goes along.
How to propagate
Making more yarrow is honestly a breeze, whether you split up a clump or grow it from seed.
DivisionEasy
Divide established clumps in spring or fall, every 2 to 3 years. · Divisions root and re-establish within one growing season.
Dividing is the easiest way to get more yarrow, and it keeps the plant from taking over at the same time. Dig up a settled clump in spring or fall every 2 to 3 years, pull off the strong bits from the outside, and pop the pieces in 12 to 18 inches (30 to 45 cm) apart. They root in and get going 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 easy too. Start it indoors 6 to 8 weeks before your last frost, or just scatter it outside in spring, and it comes up quick and flowers in its first or second year. It also self-seeds like crazy, so snip off the old flowers if you would rather not deal with a bunch of surprise seedlings.
Myths
Yarrow needs rich soil and frequent watering and feeding to thrive.
Honestly, it is the total opposite. Yarrow does its best in lean, dry, well-drained ground with full sun, and the more you baby it, the floppier and shorter-lived it gets. Being too nice to yarrow is what does it in, since wet, rich soil brings on the root rot that finishes it off.
Yarrow is a tidy clump that stays where you plant it.
Stay put? Not this one. The wild species creeps out in all directions on runners and seeds itself all over the place, so one plant can turn into a whole patch in a year or two. Just divide it and deadhead it now and then, or grab a sterile named cultivar if you would rather it stay where you put it.