HARDINESS: Zones 3 to 8
PREFERRED SOIL pH: Adaptable
PREFERRED SOIL TYPE: Average, well-drained
PREFERRED LIGHT: Sun
ATTRIBUTES: Long-lasting pastel or red flowers on ferny plants; for beds, cutting, drying
SEASON OF INTEREST: From early summer to frost, with a lull in flower production in midsummer
FAVORITES: Appleblossom', 'Coronation Gold', 'Fireland', 'Moonshine', 'Summer Pastels', The Pearl'
QUIRKS: Wet soil and mulch may lead to stem or root rot
GOOD NEIGHBORS: Balloon flower, campanula, iris, peony.
WHERE IT GROWS BEST: Sun and well-drained soil of average fertility
POTENTIAL PROBLEMS: Fungal leaf disease or root rot under damp or crowded conditions
RENEWING PLANTS: Individual plants live up to 4 years; divide when clumps cease flowering
CRITTER RESISTANCE: Excellent
SOURCE: Plants, division, seeds
DIMENSIONS: 2-3 ft (0.6-1 m) tall, 1-2 ft (0.3-0.6 m) wide
Yarrow in the Landscape
Stalwart and care-free, yarrow is a boon to any sunny garden with well-drained soil. This drought-tolerant plant has ferny green foliage that adds soft texture to the garden and can remain evergreen in mild winters. The long-lasting blooms, formed in domed clusters, are composed of many small flowers that attract butterflies and beneficial insects.
The most vigorous form, Achillea millefolium, is a spreading plant that sends out runners just below the soil. These develop root buds that break through the soil to form new plants. 'Summer Pastels' produces clouds of
flowers in cream, light yellow, pink, orange, and lilac. These 2 ft (0.6 m) tall plants are ideal to grow beside paved surfaces that heat up in summer or as a blooming groundcover in dry areas that are difficult to water.
Upright-growing A. filipendulina produces rich yellow flower clusters on stiff stems up to 3 ft (1 m) tall. This yarrow tends to stay put, growing in tight clumps that are ideal for the middle or back of borders.
The best varieties are propagated by division rather than seeds, so start with purchased, named plants.Try 'Coronation Gold' in hot-summer areas and 'Moonshine' for silvery gray foliage. Other good choices are pink-flowering 'Appleblossom', brick red 'Fireland', and 'The Pearl', which has abundant little white flowers.
For a continuous show of color, deadhead plants by clipping off the spent blooms. Yarrows bloom longer in cool weather, but you can maximize flowering in hot weather by cutting back the plants to right above the soil in midsummer, after their first flush of flowers fades. They will rebound and provide a repeat performance by fall. The flower heads make superb cut flowers, or you can gather and dry them for use in dried bouquets.
All species are easy to start from seed indoors 4 weeks before the last spring frost or in the garden after frosts pass. The seeds need light to germinate, so sprinkle them on the surface of moistened soil. If growing indoors, place the pots on a windowsill or under fluorescent lights, and keep the soil moist and at room temperature for 10-15 days. After sprouting, seedlings can be grown at temperatures as low as 50°F (10°C).Transplant seedlings into individual pots when they have several sets of mature leaves, and plant outside after the soil warms in spring.
Young yarrow plants require water when first planted, but need little care after they produce new growth. Avoid mulching, which can cause stem rot, as can chronic soil dampness or too much shade. Once spreading types get going, you may need to sever the runners of plants that wander too far.
A. filipendulina benefits from division every 3 years, when the centers of clumps begin to flower poorly. Dividing and thinning plants also improves air circulation, which helps prevent fungal leaf diseases like rust, recognized by rusty spots on leaf undersides. If problems occur, trim off and dispose of infected foliage. Add gritty gravel or compost to heavy clay soil at planting time to discourage root rot. Problem-free, pungently scented yarrow repels both insects and deer.