There are some people who consider the common yarrow plant to be a weed and nuisance. Others cherish its beauty and the wonderful biodiversity it brings to the garden. Regardless of whether you loathe or love yarrow, it is undoubtedly a plant that needs to be appreciated and better understood.
Common yarrow is native to the northern hemisphere where it grows abundantly in fields, meadows, and on disturbed soils. It establishes readily in favorable conditions and let’s just say that’s basically everywhere!
If yarrow’s reputation as an invasive weed deters you from growing it in your garden, then you may be pleased to learn that yarrow, Achillea millefolium, has many ornamental cultivated varieties such as ‘Red Velvet’, ‘Cerise Queen’ and ‘Paprika’ yarrow. All look fabulous in garden flower borders, adding splashes of vibrant color and structure.
So why grow yarrow? Apart from being a pretty addition to any flower garden, the leaves and flowers are edible and can be used fresh or dried in lots of culinary dishes and medicinal remedies. Yarrow is also an accumulator of minerals and nutrients from soils using its deep roots and producing foliage that makes an excellent fertilizer.
The large flat flower heads make a perfect landing platform for predatory and pollinating insects. Yarrow is often seen growing in orchards to attract pollinating bees in spring and to improve soil fertility when mowed and left as a mulch.
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Quick Care Guide
|Common Name||Yarrow, common yarrow, nosebleed, soldier’s woundwort, milfoil|
|Scientific Name||Achillea millefolium|
|Height & Spread||24×24 inches (60x60cms)|
|Light||Full sun to partial shade|
|Soil||Loam, sandy, silty, clay|
|Water||Water when the soil is dry|
|Pests & Diseases||Aphids and powdery mildew|
All About Yarrow
The botanical name for common yarrow is Achillea millefolium. Common names include yarrow, nosebleed plant, and soldier’s woundwort, the latter two names reflecting the plant’s medicinal properties. Achillea millefolium are native plants to most northern hemisphere countries and are especially common in North America.
You may be surprised to learn that yarrow is a member of the daisy family, Asteraceae, and not the umbellifer family despite the appearance of the flower. Look closely at the flat clusters of flowers and you will see that each individual bloom is a miniature daisy. The flowers are formed in compound corymbs producing what looks like one large flat flower head when in fact it is a cluster of many individual corymbs made up of lots of individual tightly bunched flowers. Achillea millefolium mostly has white flowers but can vary with light yellow petals and yellow centers.
Yarrow forms dense clumps of basal leaves growing to 6-12 inches (15-30cms) in length and are deep-green, feathery, and aromatic. The name ‘millefolium’ comes from the Latin meaning, ‘thousand leaf’, reflecting the feathery foliage.
Branching spikes of white flowers reaching around 24inches (60cms) in height, develop in summer and last through to fall. The leaves produced on the stems are much smaller and less abundant.
Common yarrow spreads easily via its thousands of tiny seeds and vigorous rhizomatic roots. Seeds are easily carried on the wind to new locations where they can remain viable for up to nine years before germinating. The rhizomes spread rapidly underground and will propagate easily from the smallest broken piece so be careful when you are digging them up.
As a semi-evergreen perennial, the old growth will die back in winter leaving the basal leaves to tough it out over winter. Common yarrow is an extremely hardy plant tolerating temperatures well below freezing. Plants will bulk up in early spring ready for a new flower display. Most plants will produce two flushes of blooms if you remove the early flowering spikes before the seeds begin to ripen.
Yarrow is perfect for growing in a cottage style, wildlife, or herb garden. It can also be maintained as part of a lawn or ground cover, adapting well to repeat mowing. Leaves are edible but slightly bitter so it’s best to eat them when they are young. The plant has been used throughout history for its medicinal properties to treat minor wounds, sore muscles, and stomach cramping. It is also used in the beauty industry as an astringent in body washes and shampoos.
There is no denying the architectural beauty of this plant in the flower border and the multitude of insects it attracts to your garden. The large flat flowers attract bees, wasps, butterflies, and beetles that will pollinate your crops, feed on pests like aphids and mealybugs as well as provide food for birds and small mammals.
Store-bought plants or transplants grown from seed can be planted outdoors in spring after the last frost. Choose a bright sunny location with well-drained soil either in the ground, a raised bed, or a very large container. Growing yarrow in containers and raised beds will prevent them from becoming invasive but they will require division every couple of years if plants become overcrowded. Yarrow will outgrow small containers quickly reducing the general health of the plant.
To grow yarrow, simply place the plants or transplants into the soil at the same depth they were in the pot or module tray. Planting too deep will cause the crown to rot and too shallow will cause it to dry out. Space plants 12-24 inches (30–60cms) apart and keep the soil moist but not wet until established.
Yarrow is generally self-sufficient. In the right growing conditions, they are pretty much indestructible and very easy to grow.
Sun and Temperature
Yarrow grows best in full sun but can tolerate light shade. Too much shade and the stems may become leggy, weak, and require staking. Yarrow can tolerate temperatures down to -13°F (-25°C) as well as warm weather and prolonged periods of drought. Once temperatures rise above 86°F (30°C) plants may begin to suffer heat damage.
USDA hardiness zones 3-7 are best suited to grow yarrow. Old stems and foliage will die back naturally in fall leaving just the basal leaves which protect the crown and roots over winter. No additional protection is needed.
Water and Humidity
As a drought-tolerant plant, yarrow can go several weeks without irrigation. You can wait until the soil is completely dry before watering. However, to maintain your yarrow in healthy, tip-top condition it’s best to keep the soil slightly moist. Water using soaker hoses managed on a timer or water by hand with a watering can or hose with the water directed at the soil.
Yarrow does not like to have their roots permanently wet, so check soil moisture levels if plants are showing signs of stress. Watering is not necessary over winter.
Yarrow is not fussy when it comes to soil type. It grows well in sandy, silty, loam, and clay soil as long as they are well-drained. Avoid overly rich soils as they encourage fast leggy growth that can’t sustain the weight of the flower heads. The optimum pH for yarrow is 6 to 8.5.
Fertilizing yarrow can result in weak, spindly growth. Yarrow prefers well-drained, poor soil, accumulating minerals and nutrients from deep within soils and storing them in the leaves. Leaves can also be harvested and used to make liquid fertilizer or as mulch.
Cut the first flowering stems back in early summer to encourage a second bloom in late summer/early fall and again in late fall as part of a general garden tidy-up. Removing seed heads before they ripen will also reduce the risk of self-seeding.
If left to their own devices, yarrow can quickly encroach on other plants in the garden becoming invasive and difficult to manage. To avoid this, lift and divide yarrow every few years to control their size and reduce spread.
Start seeds off indoors in spring, 6-8 weeks before the last frost, or in early fall for planting out the following spring. Sow seeds into module trays filled with moist, free-draining potting compost and cover lightly with sieved compost or vermiculite. Place trays somewhere sunny and warm to germinate. When all risk of frost has passed, space your transplants 12-24 inches (30–60cms) apart in a sunny location in well-drained soil.
Yarrow seed germination can be slow and sporadic. An easier alternative is to start off with shop-bought plants or divisions in late spring. Space plants 12-24 inches (30–60cms) and water in well.
You can take your own divisions from mature yarrow in fall or spring. Carefully dig around the perimeter of your plant and tease it out of the ground. Using either a sharp knife or two forks back to back inserted through the center of the plant, cut the crown into as many divisions as you require, making sure each division has plenty of roots.
Yarrow grows well in most environments and suffers from very few pests and diseases. The main problem when growing yarrow is managing its vigorous growth and its potential to become invasive. Here are a few tips to help you deal with any issues that may arise.
There are a few actions you can take to keep yarrow under control. These include deadheading spent flowers to prevent self-seeding; regularly dividing plants to keep size in check or growing yarrow in a raised bed or very large container to limit the spread.
Wilting or lack of vigor can be an indication that the soil is too wet. Yarrow does not like to grow in wet conditions which can lead to stem or root rot. Reduce watering to allow the soil to dry out or transplant into soil with improved drainage.
A weak, spindly plant may be the result of soil that is too fertile or a plant that does not have enough sunlight. To resolve, move plants to a full sun location and hold off on the fertilizer.
The young shoots of yarrow can be attacked by aphids (Aphidoidea), small pests that feed on the sap of new growth. Companion planting with marigolds or calendula will help deter aphids and encourage beneficial insects into the garden to feed on them. Alternatively, spray with an organic insecticidal soap or neem oil. Squishing aphids with fingers or a quick blast of water can also help to reduce numbers.
Yarrow is susceptible to powdery mildew if it becomes congested or overshadowed. It grows as thick dust on leaves, inhibiting photosynthesis and hindering growth. Maintain good garden hygiene, removing infected foliage to prevent the disease from spreading and reinfection in subsequent years. Provide adequate sunlight and good air circulation and divide large clumps if they become overcrowded. Treat affected plants with organic fungicides such as sulfur or potassium bicarbonate, prior to or on first sight of disease.
Frequently Asked Questions
Q: Does yarrow like sun or shade?
A: Yarrow prefers to grow in full sun but can tolerate light shade growing conditions.
Q: Is yarrow poisonous to humans?
A: The leaves of Achillea millefolium are edible and have many culinary and medicinal uses.
Q: Do yarrow plants spread?
A: Yarrow plants spread by underground rhizomes and self-seeding. In optimum growing conditions yarrow can become quite invasive.