Yarrow is one of those plants that rewards neglect more than fussing — get the soil right and it'll largely look after itself. The cardinal rule is drainage: yarrow absolutely hates sitting in wet soil and will rot or grow lanky and disease-prone if the ground holds moisture. If your beds are heavy clay, work in grit or coarse sand before planting, and resist the urge to enrich with compost — lean soil keeps the stems upright and the plant compact. Direct sow onto the surface in early spring, pressing seeds lightly into the soil without covering them, as they need light to germinate. Alternatively, start transplants indoors 6–8 weeks before your last frost date and plant out after danger has passed. The most common mistake gardeners make is planting in too much shade or over-watering; both lead to floppy growth and powdery mildew. Divide clumps every 2–3 years in spring to keep the plant vigorous and prevent it from spreading beyond its welcome.
Yarrow has one of the longest medicinal histories of any garden plant — archaeological evidence suggests humans have been using it for at least 60,000 years. Traditionally it was applied directly to wounds to staunch bleeding, earning it folk names like "soldier's woundwort" and "staunchweed." A tea made from the aerial parts (leaves and flowers) is used in herbalism to break fevers by promoting sweating, and as a gentle bitter tonic to support digestion and ease bloating. It has a mild anti-inflammatory action and was historically taken for menstrual cramps. On the culinary side, young yarrow leaves have a pleasantly bitter, slightly peppery flavour — use them sparingly in salads, stir through herb butters, or add a small handful to a frittata the way you'd use other assertive herbs. The flavour is strong, so a little goes a long way. Companion-planting wise, yarrow is a genuine workhorse: it attracts predatory wasps, hoverflies, and ladybirds that keep aphid populations in check nearby, making it a brilliant neighbour for roses, calendula, and chamomile.