Yarrow in Zone 7B — Mid-Atlantic

Yarrow is a fantastic addition to any Mid-Atlantic garden. Its fern-like foliage and clusters of colorful flowers add beauty, and it attracts beneficial insects like ladybugs and lacewings, which help keep pests in check. Plus, it's drought-tolerant, making it perfect for our humid summers and periods of unpredictable rainfall.

Our four distinct seasons and 214-day growing season give you plenty of time to establish Yarrow. Just watch for late frost in spring and prepare for the humidity that can sometimes lead to fungal issues. With a little planning, you can enjoy Yarrow's beauty and benefits from early summer through fall.

Starting Yarrow indoors in the Mid-Atlantic gives you a head start, but it's not always necessary. If you want blooms the first year, starting indoors is a good idea. Otherwise, direct sowing works just fine.

To start seeds indoors, sow them from mid January through early February, about eight weeks before the last expected frost. Use seed trays with a good seed-starting mix and provide warmth and light. Bottom watering helps prevent damping-off, a common problem with seedlings.

Transplanting Yarrow outdoors in the Mid-Atlantic should happen from mid March through mid April, once the danger of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space the plants 12-18 inches apart in a sunny location. Keep an eye on the weather, as we sometimes get temperature swings this time of year. If a late frost is predicted, cover the young plants to protect them. Since Yarrow is a perennial, consider buying starts if you want flowers in the first year.

Direct sowing Yarrow is a straightforward method for Mid-Atlantic gardeners. You can direct sow from early April through mid August. The soil needs to be workable and the temperatures consistently warm enough for germination.

Prepare the soil by loosening it and removing any weeds. Scatter the seeds on the surface and lightly press them into the soil. Keep the soil moist until the seedlings emerge, then thin them to 12-18 inches apart. Direct sowing is easy, but you might not get flowers in the first year.

Yarrow is wonderfully drought-tolerant once established, making it a great choice for our Mid-Atlantic climate with its even rainfall. However, young plants need consistent moisture to get started. The key is to avoid overwatering, which can lead to floppy growth and root rot, especially with our humid summers.

During the first few weeks after planting, water deeply whenever the top inch or two of soil feels dry to the touch – use the finger test! Typically, this means watering about once a week, providing about an inch of water each time. As the plants mature, you can reduce watering frequency.

Water at the base of the plants rather than overhead to minimize the risk of fungal diseases in our humid environment. Signs of underwatering include wilting leaves and dry, brittle stems. Overwatering can cause yellowing leaves and a mushy stem base. A layer of mulch helps retain moisture and suppress weeds, but be sure to keep it away from the plant's base to prevent rot.

Pruning Yarrow is simple and helps keep it looking its best in your Mid-Atlantic garden. Deadheading spent flowers encourages a second flush of blooms and prevents the plant from self-seeding too aggressively. Simply snip off the flower heads as they fade throughout the growing season.

In the fall, after the first frost around early November, cut the plant back to its basal foliage. This helps tidy up the garden and prepares the plant for winter dormancy. Yarrow can be aggressive, so divide the clumps every 2-3 years to keep it in check.

You can expect your first Yarrow harvest in the Mid-Atlantic from early June through early November, about 65 days after planting. Harvest the flowers for drying when they are fully open and their color is vibrant. These make excellent dried flowers, holding their shape and color well.

To harvest, cut the stems just above a leaf node with sharp, clean scissors or pruners. This encourages the plant to produce more flowers. Harvest regularly to promote continuous production throughout the season.

As the first frost approaches in early November, you can harvest any remaining flowers for drying. Even if they aren't perfect, they can still be used in crafts or potpourri. Leaving some flower heads on the plant in the fall provides seeds for birds and other wildlife.

Here are three common problems you might encounter with Yarrow in the Mid-Atlantic:

Aggressive Spreading

• What it looks like: Yarrow spreads via rhizomes, quickly forming dense clumps and potentially overtaking nearby plants.
• What causes it: Our region's reliable rainfall and moderate-to-hot summers provide ideal growing conditions for Yarrow, allowing it to spread rapidly.
• How to fix/prevent it: Plant Yarrow in a contained area or regularly divide the clumps every 2-3 years to control its spread. Remove unwanted seedlings promptly.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes flower heads. Leaves may curl, yellow, and eventually die.
• What causes it: Powdery mildew thrives in our warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning to open up the plant's center. Remove and discard affected leaves. Apply neem oil or potassium bicarbonate sprays. Milk spray (1 part milk to 9 parts water) can also be effective.

Aphids

• What it looks like: Clusters of tiny, soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Aphid populations explode in our warm, humid summers. They are sap-sucking insects that weaken the plant.
• How to fix/prevent it: Knock aphids off with a strong spray of water. Encourage natural predators like ladybugs and lacewings. Use insecticidal soap for heavy infestations, or neem oil for a systemic treatment.

Mid-Atlantic Specific Challenges: The moderate-to-hot heat and humid summers in the Mid-Atlantic can create conditions that favor powdery mildew and aphid infestations in Yarrow. Regular monitoring and proactive measures are essential to keep your plants healthy and thriving.

Yarrow makes a great companion plant for many vegetables and herbs in the Mid-Atlantic garden. It attracts beneficial insects like ladybugs and lacewings, which prey on pests that can damage tomatoes and peppers. Planting Yarrow near these vegetables can help reduce pest pressure naturally.

Yarrow is also a good companion for herbs, as it can improve their essential oil production. Strawberries benefit from Yarrow's presence, as it attracts pollinators and can help deter some pests. Avoid planting Yarrow near plants in the cabbage family, as it can attract cabbage moths.