Yarrow in Zone 5A — Great Plains

Yarrow is a workhorse in a Plains garden. It's not just pretty with its clusters of blooms, but it's incredibly drought-tolerant, attracts beneficial insects, and the dried flowers add a touch of prairie charm to your home through the long winters. Plus, that subtle fragrance is a welcome addition to our sometimes harsh, windswept landscape.

Our extreme weather here can be a challenge, from late spring frosts to the occasional summer hail. But with Yarrow, a little planning goes a long way. Its adaptability makes it a great choice for our 168-day growing season.

Starting Yarrow indoors in our region is definitely an option, but not always necessary. If you're aiming for blooms the very first year, it might be worth it.

Start your seeds indoors from early to late February, about eight weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and keep them warm – a heat mat helps. Bottom watering is key to prevent damping off; set the tray in a shallow dish of water and let the soil soak it up. Remember, spring here can be unpredictable, so be ready to adjust your transplant schedule if we get a late cold snap.

Transplant your Yarrow seedlings outdoors from mid April through early May, once the danger of hard frost has passed. Before you commit them to the garden, harden them off. Give them about a week of gradual exposure to the outdoors, increasing the time each day.

Space them 12-18 inches apart, giving them room to spread. Keep in mind that Yarrow is a perennial, so choose their location carefully. If you're eager for flowers in the first year, you can also buy established starts from a local nursery.

Direct sowing Yarrow is a perfectly viable option for us Plains gardeners. You can sow seeds directly into the garden from late April through late July.

Prepare the soil by loosening it and removing any weeds. Yarrow prefers well-drained soil, so don't worry about amending it too much. Sprinkle the seeds on the surface and gently press them into the soil. Keep the soil consistently moist until the seedlings emerge. Space them 12-18 inches apart once they're established. The downside? You likely won't see blooms until the second year.

Yarrow thrives on neglect when it comes to watering, which makes it perfect for our variable Plains climate. Once established, it's very drought-tolerant. Overwatering is a bigger problem than underwatering in our region.

During the heat of summer, especially if rainfall is scarce, check the soil before watering. Stick your finger about two inches deep; if it's dry, then it's time to water. Give them about an inch of water per week during dry spells. Water at the base of the plant to avoid wetting the foliage, which helps prevent fungal issues in our low-to-moderate humidity.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can cause yellowing leaves and floppy growth. A light layer of mulch, like shredded bark or straw, will help retain moisture and suppress weeds, but don't overdo it – Yarrow prefers well-drained soil.

Deadheading is key to keeping your Yarrow blooming throughout the season. Snip off the spent flowers as soon as they start to fade. This encourages the plant to produce more blooms.

Cut back the flower stalks to the basal foliage, which is the cluster of leaves at the base of the plant, in the fall after the first frost hits around early October. Yarrow can be a bit aggressive, so divide the plants every 2-3 years to keep them from taking over your garden.

You can start harvesting Yarrow flowers from late June through mid October, about 65 days after planting. The best time to harvest is when the flowers are fully open.

Cut the stems just above a leaf node. This encourages the plant to produce more flowers. Yarrow is an excellent dried flower, so hang the stems upside down in a cool, dark, dry place to dry them. Keep harvesting throughout the season to encourage continuous production. Even as the first frost approaches in early October, you can still harvest any remaining blooms for drying.

Here are some common issues you might face with Yarrow in the Great Plains:

Spreading Aggressively

• What it looks like: Yarrow popping up in areas where you didn't plant it, gradually taking over garden beds.
• What causes it: Yarrow spreads through rhizomes (underground stems). Our fertile prairie soil encourages vigorous growth.
• How to fix/prevent it: Plant Yarrow in a contained area, like a raised bed or surrounded by edging. Divide the plants regularly (every 2-3 years) to keep them in check.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves may curl, yellow, and die.
• What causes it: Fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it. The temperature swings we get here can create ideal conditions.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is 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: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap for heavy infestations. Neem oil works systemically.

Great Plains Specific Challenges: Our hot summers and variable rainfall can stress Yarrow, making it more susceptible to powdery mildew if air circulation is poor. While Yarrow is drought-tolerant, prolonged dry spells will still require supplemental watering, especially for newly planted Yarrow. The wind can also be tough on taller Yarrow varieties, so consider staking them or planting them in a sheltered location.

Yarrow is a great companion plant in the Plains garden. It attracts beneficial insects like ladybugs and hoverflies, which prey on pests that can damage other plants.

Good companions include:

• Tomatoes and Peppers: Yarrow attracts beneficial insects that help pollinate and protect these crops from pests.
• Herbs: Many herbs, like rosemary and thyme, benefit from the increased pollination and pest control Yarrow provides.
• Strawberries: Yarrow can help deter pests that attack strawberries.

While there aren't many "bad" companions for Yarrow, avoid planting it too close to plants that prefer very rich, moist soil, as Yarrow thrives in drier conditions.