Yarrow (milfoil) care

Light

Yarrow needs sun on the leaves, not just bright ambient room light. Needs full sun, at least 6 hours daily, for sturdy, upright growth and good flowering. In shade it grows leggy, flops, and flowers sparsely. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Water yarrow when the top 5 cm of soil is dry; every 10-14 days once established. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Highly drought-tolerant once rooted and dislikes wet feet. Water to establish, then only in extended drought. Overwatering and rich soil cause floppy growth and rot.

Soil and pot

Yarrow grows best in lean, free-draining soil. Thrives in poor, dry, sandy or gravelly ground across a wide pH range. Rich, moist or heavy soils produce lax growth and worsen its spreading tendency; sharp drainage is best. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Yarrow sits happiest at around Ambient outdoor humidity humidity and -30 to 30°C (-22 to 86°F). A hardy meadow plant indifferent to humidity. Open spacing and airflow in humid climates reduce powdery mildew, to which it is somewhat prone. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed yarrow sparingly. None to minimal. Yarrow performs best in unimproved soil and rarely needs feeding; fertiliser produces weak, floppy stems. Skip feeding in average ground. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on yarrow in the Growli community. Each is annotated with the most common cause so you know where to start.

• Aggressive rhizomatous spread — Spreads quickly by underground runners and can swamp neighbours; divide regularly or plant where it can roam freely.
• Flopping stems — Tall cultivars splay open in rich soil or shade; grow lean and sunny, or support, and cut back after first flowering for sturdier regrowth.
• Powdery mildew — Grey foliar coating develops in humid, crowded conditions; improve airflow, avoid overhead watering and cut back affected growth.
• Toxic to grazing animals — Contains glycoalkaloids and lactones that cause GI upset and dermatitis in pets and livestock; site away from animal areas.

Propagation

Readily propagated by division of clumps in spring or autumn (the easiest method), by basal cuttings, or from seed surface-sown in spring. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Yarrow is toxic to pets. ASPCA-listed as toxic to dogs, cats and horses. The toxic principles are glycoalkaloids (achillein), monoterpenes and sesquiterpene lactones (achillin); ingestion can cause vomiting, diarrhoea, colic, drooling, anorexia, dermatitis and depression. Keep pets and livestock from grazing it. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Yarrow deep-dive guides

Every aspect of yarrow care, each with its own calibrated guide:

• Yarrow watering schedule
• Yarrow light requirements
• Best soil mix for yarrow
• Yarrow fertilizing guide
• When to repot yarrow
• How to propagate yarrow
• Yarrow growth rate & size
• Yarrow cold hardiness
• Yarrow temperature & humidity
• Is yarrow toxic to cats & dogs?
• Is yarrow toxic to cats?
• Is yarrow toxic to dogs?

Related guides

Yarrow is also known as yarrow, common yarrow, and milfoil.

• Basil care — light, water and common problems
• Herb garden care — light, water and common problems
• Mint care — light, water and common problems
• All 2464 plant care guides in the Growli library