Achillea

Intro/Brief Description

Family: Asteraceae

Genus: Achillea L.

Common Name: Yarrow

The genus was named Achilles from Greek mythology. Achilles' soldiers used yarrow to treat injuries, thus it is also called healall and bloodwort.

Achillea is considered an invasive species in some parts of the United States.

Examples

Achillea tomentosa. Common name - wooly yarrow. Usually a low growing mat averaging 6” in height, though sometimes reaching 12”. This rapidly growing plant can easily become evasive. Pull unwanted seedlings as necessary. Hardy in zones 3-8.

Achillea millefolium. Common name - common yarrow, milfoil. One to two feet tall with groups of small white flowers clustering together.

Achillea filipendulina 'Parker's Variety.' Grows three to four feet tall and spreads two to three feet wide. Hardy to zone 3.

Achillea 'Moonshine' grows one to two feet tall and spreads three-quarters to one foot. It is a hybrid plant with bright yellow flowers. Hardy in zones 3 to 8.

Achillea 'Feuerland' is a hybrid with an interesting bloom. The flowers start out blood red but fade over time to golden yellow. It grows two to three feet tall and spreads out one to two feet.

Special Features

Common yarrow has pretty fern-like foliage. It’s a long-lasting cut flower that is easily dried. It has a mild earthy scent. Achillea is a food source for some moths, butterflies and skippers.

Hardiness

Hardy in USDA zones 3-10.

Growth Habit

Achillea varies from six inches to four feet in height. Some varieties have only one flower stem yet other varieties have many.

Bloom Time

Blooms appear in June and last several weeks before going to seed. You can encourage second blooms deadheading back to the basal leaves. The natural flower colors are are white, shades of pink and lavender, and yellow. Wild Achillea is usually white. Hybrids come in a wide variety of colors and shades. Some bloom in one color at the start and change to another color at the end of the bloom cycle. Blooms appear as flat clusters of many individual flowers.

Propagation

Seeds sown in the spring might produce fall blooms, otherwise, first flowers will appear in early summer of the following year. Divide clumps in the spring every three to four years.

Germination OR Cuttings

Stratification, scarification, temp, light, time and any special care while in seedling stage. If cuttings can be taken or are the only form of propagation please provide the information here. Seeds germinate best when soil temperature is between 65° and 75°. Outdoor seeds need approximately two weeks to germinate. Seeds that are germinated in pots or trays indoor may sprout in as little as five days.

Transplanting

Achillea can be divided and transplanted as mature plants, started from seed and transplanted as seedlings, and grown by direct seeding. When planting or transplanting allow one to two feet between plants. Achillea spreads through self seeding.

Soil

Achillea prefers well-drained moist to dry soil. It doesn’t do well in highly fertile and clay soils.

Irrigation

Achillea is highly drought tolerant. It does not like wet soil. At most, soil should be moist.

Sunlight

Achillea will grow in partial shade but prefers full sun. Plants grown in shed can become leggy and weak, easily blown over in wind. If you’re growing Achillea in shade you might need to stake it to ensure it isn’t destroyed by wind or heavy rains.

Care

Achillea does not light highly fertile soil. When transplanting you can add a little compost to the new hole but it’s unlikely to be necessary or even appreciated.

Pests

Aphids will occasionally attack an already weakened plant but they generally are not a serious threat. Mealy bugs might be a problem in the south but are also not a serious threat.

Disease

Please provide information on the common diseases that afflict this genus.

Bacterial gall can cause a serious problem for Achillea.

Powdery mildew may affect Achillea but it rarely kills the plant.

Rust is a fungal pathogen. If you experience this problem you should clear the garden of all infected plants to help control its spread. Rust spreads through pores. Throw the diseased plants away - do not compost them.

Rhizoctonia and Phytopthora are two kinds of fungus that cause root rot in Achillea. It’s hard to control root rot because by the time symptoms show in the plant, it’s too late. Anti-fungal treatments are seldom effective.

Crown and collar rot are bacterial rots. They take advantage of injury to the plant. This is easily avoided by growing Achillea in well-drained soil only.

Additional Info

Almost every variety of Achillea can be dried. They’re widely used in cottage gardens, as borders and in rock gardens. They’re such a simple plant to grow that you can literally plant it and forget it if you ware not concerned with it spreading. If you deadhead you’ll get a second bloom but if not, it will go to seed, creating another interesting look.

References

Wikipedia,

The Garden Helper Achillea [1]

Plant Profiles, USDA Natural Resource Conservation Service. Achillea millefolium. [2]

Missouri Botanical Garden [3]
Kemper Center for Home Gardening