When to Plant Yarrow: Seed Starting, Spacing, Dividing and Keeping Achillea Upright

Common yarrow (Achillea millefolium) is a ferny-leaved perennial with flat flower clusters, native to temperate Europe, Asia and North America (NC State). It grows 1 to 3 feet tall, blooms in summer and is hardy in zones 3a to 9b (NC State). The wild form is white; garden cultivars such as 'Paprika', 'Cerise Queen' and 'Strawberry Seduction' come in reds, pinks and yellows (NC State). Fernleaf yarrow (A. filipendulina), native to central and southwestern Asia, has yellow heads and grows 3 to 4 feet tall (NC State).

When to plant yarrow

Use our planting calendar to count back from your last frost. The sources differ on lead time, 6 to 8 weeks (Mississippi State) versus 8 to 10 weeks (Outsidepride, Almanac); our reading is that 8 weeks suits most people, since Outsidepride says yarrow can bloom its first year from an early start. Mississippi State germinates seed at 65 to 72°F with even moisture and high light, and expects seedlings in 10 to 14 days. Harden seedlings off for 7 to 10 days before planting out (Outsidepride).

How to plant yarrow

Mississippi State recommends raised beds and drip irrigation in the Southeast, because long wet spells raise the risk of crown and root diseases. The Almanac loosens the soil 12 to 15 inches deep and mixes in 2 to 4 inches of compost, but warns that overly rich soil makes stems floppy.

Watering, feeding and deadheading

• Water only in dry spells. Clemson calls established yarrow extremely drought resistant; the Almanac waters only when rain falls short of an inch a week.
• Feed very little. Mississippi State says yarrow needs only modest fertility and extra nitrogen gives weak stems that fall over; NC State warns against over-feeding and over-watering fernleaf yarrow. Outsidepride and the Almanac use compost instead, the Almanac a thin layer each spring.
• Deadhead to prolong bloom and limit spread by seed (NC State). Clemson and the Almanac deadhead in midsummer to extend bloom or get a second flush.
• Divide every 2 to 3 years (Clemson, Mississippi State, Outsidepride) or 3 to 5 years (Almanac) to keep clumps vigorous and in bounds.
• Wear gloves. NC State advises gloves to prevent contact dermatitis, tags yarrow as a problem plant for cats and dogs and suggests not planting it where pets roam.

Yarrow in containers

NC State lists containers among the uses for fernleaf yarrow and notes the shorter 'Altgold' at about 2 feet. Our reading is to use a gritty, free-draining mix and a pot with plenty of drainage holes, since every source ties yarrow's problems to wet soil, and to skip fertilizer (GardenPal reasoning).

Fall and winter

• Cold is rarely the problem. Yarrow is hardy to zone 3 (NC State); Mississippi State and Clemson link losses to soil that stays wet, so good drainage matters more than mulch (our reading).
• Fall dividing is an option. The Almanac divides in early spring or fall, but Iowa State's default is early spring.
• Seed heads. Leaving seed heads lets common yarrow self-sow, which NC State says can make it weedy, so our reading is to cut them unless you want it to spread.

Pests and problems

Yarrow's main problems come from wet, rich soil. NC State calls stem rot and powdery mildew rare on common yarrow but warns of root rot in too-wet soil; Clemson says yarrow is short-lived in wet sites because of root rot and powdery mildew, and NC State adds rust on fernleaf yarrow. Mississippi State lists aphids, mealybugs, thrips and spittlebugs as the main pests, and notes that tight spacing reduces air flow and raises disease risk. Flopping usually means too much fertilizer or water (Mississippi State, NC State); Clemson says the Galaxy hybrids resist lodging. NC State and Clemson call yarrow deer resistant, and NC State adds rabbits.

Yarrow around the vegetable garden

Yarrow is one of the daisy-family flowers we list in flowers that attract beneficial insects. Clemson and the Wildflower Center cite the Xerces Society, which recognizes it as having special value to native bees and supporting conservation biological control (the predatory and parasitoid insects that eat pests, as Clemson puts it). Clemson adds that it feeds lady beetles and butterflies. Its small, flat flower heads suit small beneficial insects (GardenPal reasoning). Because it likes lean, dry soil and spreads, plant it along a sunny, unwatered edge of the plot, not in rich, irrigated beds (our reading). Good neighbors include coreopsis, lavender, salvia and black-eyed Susans. Clemson's companion list includes butterfly milkweed and smooth penstemon.

Frequently asked questions

When should I plant yarrow?

In spring or early summer after the last frost (Almanac, Mississippi State). Start seed indoors 6 to 10 weeks before that date.

Should I cover yarrow seeds?

No. Press them lightly onto the mix, because light aids germination (Mississippi State, Outsidepride). Expect sprouts in 10 to 14 days at 65 to 72°F (Mississippi State).

How far apart should I plant yarrow?

12 to 18 inches (Clemson). Mississippi State gives 9 to 18 inches and the Almanac 1 to 2 feet.

Why is my yarrow flopping over?

Usually too much nitrogen, water or shade (Mississippi State, Clemson). Grow it lean in full sun and go easy on feeding.

Does yarrow spread?

Common yarrow spreads aggressively by rhizomes and seed (NC State). Sterile cultivars such as 'Petra' (Clemson) and non-reseeding 'Coronation Gold' (NC State) stay put better.

When should I divide yarrow?

In early spring as new growth appears (Iowa State), every 2 to 3 years (Clemson, Mississippi State).