How to Grow and Care for Yarrow Plants

Yarrow is a medium-sized plant in the aster family that is available with a variety of flower colors. It is easily identified by its feathery foliage and flattened flower clusters. Yarrow prefers full sunlight and well-draining soil, and it is used in butterfly gardens, as an edging plant, and in rock gardens.

You can plant yarrow in spring and enjoy it as a long-blooming perennial. Just keep in mind that this species is toxic to pets.

Yarrow Plant Care

Yarrow thrives across much of the United States except in extreme climates such as deserts and high mountains. A tough plant with a tendency to spread by rhizomes, yarrow may even naturalize in your yard.

Yarrow plants have to be staked in some situations, or else you may find the stems flopped down on the ground after high winds. The best time to plant or transplant yarrow is in spring.

Light

Provide yarrow with full sun to keep its form compact, to encourage optimal blooming, and to discourage fungal attacks.

Soil

Good drainage is all yarrow asks for. It will tolerate clay soil better than many plants, but it grows best with good drainage. It flourishes in multiple soil types and isn't a heavy feeder.

Water

Once established, yarrow is drought-tolerant. Because overwatering can promote the fungal diseases to which yarrow is prone, it is better to err on the side of under-watering the plant in all but the driest of conditions.

Temperature and Humidity

As a plant that can thrive across as wide a swath as zones 3 to 9, yarrow is quite tolerant of weather conditions. It is cold-hardy and can take heat well enough to grow in zone 9.

Fertilizer

Yarrow plants don't require great soil fertility. An annual dose of compost in the spring will invigorate the plant but is not necessary. In fact, if you are worried about it spreading out of control, withhold fertilizer from it altogether.

Types of Yarrow

There are several cultivars of yarrow to choose from; all can be grown in zones 3 to 9:

• 'Apple Blossom': Flowers soft pink to pale rose to purple; 2 to 3 feet tall and wide
• 'Cerise Queen': Deep pink flowers; dark green foliage; 2 feet tall, with a similar or somewhat greater spread
• 'Moonshine': Lemon-yellow flowers; silvery leaves; 18 inches tall x 24 inches wide
  
• 'New Vintage Red': Bright red flowers; bright green leaves; 10 to 14 inches tall x 10 to 12 inches wide
  
• 'Paprika': One of the most popular yarrow plants; brick red flowers with yellow centers; 24 inches tall by 30 inches wide
• 'Peachy Seduction': Peach-pink flowers; 23 to 36 inches tall x 18 to 24 inches wide
• 'Red Velvet': Fade-resistant red flowers; 2 to 3 feet tall and wide
• 'Salmon Beauty': Flowers start out salmon-pink and fade to creamy-yellow; 2 to 3 feet tall x 1 to 2 feet wide

Pruning

As the summer wears on, the plant can start to get leggy (especially in hot, humid climates). If this happens, and if you're content that you've enjoyed enough blooms for a while, cut the plant back to a more compact size with pruners.

This reduction in plant height will help avoid excessive flopping and the consequent need for staking. 

Propagating Yarrow

When it comes to propagation, yarrow's tendency to spread (which, in other respects, can be problematic) makes your life easy.

After spreading occurs, simply divide your plants (in spring) and make a transplant to the new area you have chosen. For those who either don't want to wait that long or don't want to bother with division, purchase starts at your local garden center (yarrow is widely available).

How to Grow Yarrow From Seed

You can also grow yarrow from seed. Sow the seed indoors in early spring to get a jump on the season (from sowing time to blooming time will take about three months), or, if you don't mind waiting, sow the seed outdoors after all danger of frost has passed and anticipate flowers in fall.

If you choose to sow the seed indoors, here's what you have to do:

1. Fill a seeding tray with sterile soilless potting mix or seed starter mix. 
2. Sow the seeds on top of the mix. Don't cover them with soil.
3. Make sure the seeds have good contact with the soil by pressing down on them.
4. With a spray bottle of water, mist the mix. The surface of the mix should be moist but not soggy.
5. Put the seeding tray in a warm, sunny window until germination occurs (about two weeks).
6. Harden off the new plants so that they gradually become accustomed to the outdoors.
7. Transplant them to the spot you've selected for them in the garden after danger of frost has passed.
   

How to Get Yarrow to Bloom

If your plant isn't blooming, rest assured that it isn't due to a lack of fertilization. Yarrow isn't a heavy feeder; it may actually bloom better in poor soil. The effect of fertilizing is usually an increase in foliage and an enhanced tendency to spread. If left alone, yarrow should have no trouble blooming.

As soon as you see your yarrow blooming in the summer, get ready to deadhead it as the flowers fade. This will keep the plant blooming longer.

Common Plant Diseases

Yarrow's aromatic leaves discourage animal pests from attacking it for the most part. However, this perennial is susceptible to a few fungal plant diseases.

Stem Rot

Stem rot can manifest itself in spots on the bottom part of a plant's stem. The spots can be black, brown, gray, or red. The end result of this fungal disease is root decay and weakened plants that will first wilt, then die back altogether.

Powdery Mildew

Powdery mildew is that light-colored, powdery covering you often see on the leaves of a number of different kinds of plants.

It usually starts on the undersides of foliage, making it difficult to detect in time to prevent a full-blown invasion. The good news is that it's rarely fatal. In fact, this fungal disease is not serious enough to warrant spraying.