Yarrow in Zone 8B — Southeast

Yarrow is a workhorse in the Zone 8B garden. Its lacy foliage and bright blooms add beauty, and it attracts beneficial insects, helping keep pests in check. Plus, it's fantastic for dried arrangements, giving you garden color to enjoy even through our short winters.

Our long growing season here in the Southeast means you have plenty of time to get yarrow established. While the humidity can be a challenge with some plants, yarrow is surprisingly resilient if you follow a few key watering tips. With our 255-day growing season, you'll be enjoying its blooms for months!

Starting yarrow indoors is definitely an option, but honestly, it's often easier to direct sow or buy established plants, especially here in the Southeast. However, if you're after a specific variety, starting indoors gives you more control.

If you choose to start indoors, sow seeds Late December through mid January, about eight weeks before the last expected frost. Use seed trays with a good seed-starting mix, provide warmth (a heat mat is helpful), and ensure plenty of light with grow lights. Bottom watering will help prevent damping off. Our moderate springs mean you have a little extra time if you get a late start.

Transplanting yarrow is straightforward. Aim to get your seedlings in the ground Late February through late March. Be sure to harden them off for about a week before transplanting. Gradually expose them to outdoor conditions.

Space plants 12-18 inches apart to allow for their clumping growth habit. While our weather can be unpredictable during this time, yarrow is pretty tough, so a light frost shouldn't be a problem. Keep in mind that yarrow is a perennial, so buying starts will give you flowers the first year.

Direct sowing yarrow is a simple and effective way to get it growing in your garden. You can sow seeds directly into the ground Early March through early September. This long window takes advantage of our long growing season.

Prepare the soil by loosening it and removing any weeds. Yarrow isn't picky, but well-drained soil is key. Scatter the seeds lightly over the surface and gently press them into the soil. Keep the soil consistently moist until germination. Space plants 12-18 inches apart, thinning as needed.

Yarrow is a champion when it comes to drought tolerance, making it a great choice for our hot and humid Southeast summers. Once established, it thrives on neglect, which is perfect for busy gardeners. However, getting the watering right, especially early on, is important.

In the Southeast, you'll want to water newly planted yarrow regularly until it's established. After that, let the rain do most of the work. During dry spells, use the "finger test" – stick your finger about two inches into the soil. If it feels dry, it's time to water.

Generally, established yarrow only needs about an inch of water per week, including rainfall. Water at the base of the plant rather than overhead to minimize humidity around the foliage, which can help prevent fungal diseases.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can lead to root rot and floppy growth. A light layer of pine straw mulch can help retain moisture without suffocating the roots, which is helpful given our wet summers.

Pruning yarrow is essential for maintaining its appearance and encouraging continued blooming. The key is to deadhead spent flowers regularly throughout the growing season. This prevents the plant from putting energy into seed production and encourages more blooms.

Simply snip off the flower heads just below the lowest flower. You can do this as soon as the flowers start to fade. Towards the end of the season, after the first frost around mid- November, cut the plant back to its basal foliage.

Yarrow can be aggressive, so every 2-3 years, divide the clumps in the spring to prevent them from taking over your garden. This will also rejuvenate the plant and keep it healthy.

You can expect your first yarrow harvest starting Mid May through late November, depending on when you planted. Yarrow is ready to harvest when the flowers are fully open and vibrant. This is usually about 65 days after planting.

To harvest, simply cut the stems just above a leaf node. This encourages new growth and continued production. Yarrow is excellent for dried flower arrangements, so hang the stems upside down in a cool, dark, and dry place to dry them.

Yarrow will continue to produce blooms throughout our long summer if you keep deadheading. As the first frost approaches in mid- November, harvest any remaining flowers you want to dry.

Yarrow is generally a low-maintenance plant, but here in the Southeast, we do have a few common issues to watch out for: aggressive spreading, powdery mildew, and aphids.

Aggressive Spreading

• What it looks like: Yarrow quickly expands beyond its intended area, crowding out other plants.
• What causes it: Yarrow spreads via rhizomes (underground stems), and it thrives in our long growing season.
• How to fix/prevent it: Plant yarrow in a contained area, such as a raised bed or surrounded by edging. Divide the plant every 2-3 years to control its spread.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes flower heads. Leaves may curl, yellow, and die.
• What causes it: Various fungi thrive in warm days, cool nights, and moderate humidity. Ironically, dry leaf surfaces actually favor it. Our humid summers can exacerbate this.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning to open up the canopy. Remove affected leaves promptly. Neem oil or potassium bicarbonate sprays can help. A milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

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: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: A strong water spray can knock them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap is effective for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer, which attracts them.

Southeast Specific Challenges: Our hot, humid summers and wet-summer rainfall create an environment where powdery mildew can be a recurring issue. Be vigilant about air circulation and consider planting yarrow in a location with good morning sun to help dry the foliage quickly. Also, be prepared to manage its spreading habit, especially in our long growing season.

Yarrow is a great companion plant for many vegetables and herbs in the Southeast garden. Its flowers attract beneficial insects like ladybugs and lacewings, which help control pests.

Good companions:

• Tomatoes and Peppers: Yarrow attracts beneficial insects that prey on tomato hornworms and aphids, common pests in our gardens.
• Herbs: Yarrow enhances the essential oil production of herbs like rosemary and thyme, making them more flavorful and fragrant.
• Strawberries: Yarrow attracts hoverflies, whose larvae feed on aphids that can damage strawberry plants.

Bad companions: Avoid planting yarrow near plants in the Brassica family (cabbage, broccoli, cauliflower). Yarrow attracts cabbage white butterflies, whose larvae can decimate these crops.