Achillea

Bloom Time

Yarrow flowers from early summer through early fall, producing flat-topped flower clusters (corymbs) in a wide range of colors. Peak bloom occurs in July and August, with sporadic repeat flowering if plants are deadheaded. The flowers attract butterflies, bees, and beneficial insects in enormous numbers, making yarrow one of the most important pollinator plants for sunny gardens.

Size and Growth Habit

Yarrow typically grows 1 to 3 feet tall with a spreading habit via underground rhizomes. The finely divided, feathery foliage is aromatic when crushed, forming dense basal mats of silver-green to dark green leaves. Flat-topped flower clusters rise above the foliage on stiff, upright stems, creating a quilted effect that is spectacular when viewed en masse across a meadow planting.

Hardiness Zones

Yarrow is exceptionally hardy, thriving in USDA Zones 3 through 9. It tolerates extreme cold, heat, humidity, and drought with equal ease, making it one of the most adaptable and widely naturalized garden perennials in the world.

Light Requirements

Yarrow demands full sun with at least 6 to 8 hours of direct sunlight daily. In partial shade, plants become leggy, flop over, and produce significantly fewer flowers. Full sun also intensifies flower color and produces stronger, self-supporting stems.

Soil and Water Requirements

Yarrow thrives in well-drained, average to poor soil. Rich, fertile, or consistently moist soil causes leggy growth and flopping stems that require staking. Sandy, gravelly, or lean soil produces the most compact, floriferous plants. Once established, yarrow is extremely drought-tolerant and needs supplemental water only during severe, extended dry spells.

Pruning

Deadhead spent flower clusters to encourage repeat blooming through summer and into fall. Cut plants back by one-third after the first flush of flowers to promote a more compact second bloom. Divide clumps every 3 to 4 years to maintain vigor and prevent center die-out.

Summer Care

Summer is yarrow's peak season. Deadhead regularly to extend bloom. In humid climates, ensure good air circulation to prevent powdery mildew. Yarrow is extremely heat and drought tolerant and rarely needs supplemental care during summer months.

Winter Care

Yarrow is fully dormant and cold-hardy in winter across its entire range. No special protection is needed. Cut back dead foliage in late fall or early spring. The dried flower heads provide attractive winter interest if left standing through the cold months.

Companion Plants

Pests and Diseases

• Powdery mildew: The most common issue, especially in humid conditions with poor air circulation. Improve spacing and avoid overhead watering.
• Aphids: Occasionally cluster on stems but are typically managed by natural predators such as ladybugs.
• Stem rot: Caused by poor drainage or overwatering. Ensure well-drained soil at planting time.

Common Varieties

Toxicity

Yarrow is generally considered non-toxic, though the foliage contains compounds that may cause mild skin irritation (contact dermatitis) in sensitive individuals, particularly when handling plants in full sun. Yarrow has a long history of medicinal use but should not be consumed without professional guidance.

Care Difficulty

Yarrow is one of the easiest perennials to grow. It thrives on neglect, tolerating drought, poor soil, and extreme temperatures. The only ongoing tasks are deadheading for repeat bloom and occasional division every few years.