Yarrow in Zone 3B — Great Plains

Yarrow is a workhorse in the Plains garden, offering beauty, drought tolerance, and attracting beneficial insects to your patch. Its feathery foliage and cheerful blooms add a pop of color, and it's surprisingly adaptable to our variable conditions. Plus, it's a fantastic dried flower!

Sure, we face our share of challenges here on the Plains—wind, temperature swings, and the occasional hail. But with a little planning and attention to timing, you can absolutely grow thriving Yarrow within our 118-day growing season.

Starting Yarrow indoors is an option, especially if you want blooms the first year. Otherwise, direct sowing is reliable. If you choose to start indoors, aim for early to late March, about eight weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Provide consistent warmth and plenty of light – a grow light works wonders. Don't forget to water from the bottom to avoid damping off.

Remember that early warmth can be followed by a late cold snap here, so watch the weather closely before transplanting.

Transplant your Yarrow seedlings outdoors in early May through early June, once the risk of hard frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week.

Space your plants 12-18 inches apart in a sunny spot with well-drained soil. Keep an eye out for late frosts, as these can still happen even in early May. If you buy starts for flowers the first year, you'll get a jump start on blooms.

Direct sowing Yarrow is a perfectly viable option, especially if you're not in a rush for flowers the first year. Sow the seeds mid May through late June, after the soil has warmed up.

Prepare the soil by loosening it and removing any weeds. Yarrow isn't picky about soil, but good drainage is key. Scatter the seeds lightly over the surface and gently press them into the soil. Remember to keep the soil consistently moist until seedlings emerge.

Yarrow is incredibly drought-tolerant once established, making it a great choice for our Plains climate where rainfall can be unpredictable. In its first year, however, it needs more consistent moisture.

During the first few weeks after planting or transplanting, water deeply once or twice a week, providing about an inch of water each time. Afterwards, let the soil dry out between waterings. Use the finger test: stick your finger about two inches into the soil. If it's dry, it's time to water.

After the first year, you'll rarely need to water unless we're in a prolonged drought. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our low-to-moderate humidity. Signs of underwatering include wilting leaves, while overwatering can lead to floppy growth and root rot. A light mulch of gravel or shredded bark can help conserve moisture and suppress weeds.

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

In late fall, after the first frost around mid- September, cut the plant back to its basal foliage. Yarrow can be aggressive, so divide the plants every 2-3 years to keep them in check.

You can expect your first Yarrow harvest in late July through late September, about 65 days after planting. The best time to harvest the flowers for drying is when they are fully open and the colors are vibrant.

Cut the stems long, leaving enough foliage on the plant to continue growing. Bundle the stems together and hang them upside down in a cool, dry, and dark place to dry. Harvesting regularly will encourage continued flower production. Keep an eye on the weather as first frost approaches in mid- September; harvest any remaining blooms before then.

Here are the most common problems you might encounter with Yarrow in the Great Plains:

Spreading Aggressively

• What it looks like: Yarrow spreading beyond its intended area, crowding out other plants.
• What causes it: Rhizomatous roots send up new shoots, especially in fertile soil.
• How to fix/prevent it: Plant in a contained area or divide regularly (every 2-3 years) to control spread. Be vigilant about removing unwanted shoots.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: Fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces favor it.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly 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.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings. Insecticidal soap for heavy infestations. Neem oil works systemically.

Great Plains Specific Challenges: The Plains' hot summers can stress Yarrow, making it more susceptible to powdery mildew. Variable rainfall means you need to be vigilant about watering during dry spells, especially in the first year. Wind can also be a factor, so consider planting Yarrow in a sheltered location or providing support if needed.

Yarrow makes a great companion plant for many vegetables and herbs in the Plains garden. It attracts beneficial insects like ladybugs and lacewings, which prey on pests that can damage your crops.

Good companions include tomatoes and peppers, as Yarrow repels tomato hornworms and pepper weevils. It also pairs well with herbs like rosemary and thyme, enhancing their growth and flavor. Strawberries also benefit from Yarrow's presence, as it attracts pollinators. Avoid planting Yarrow near anything that is prone to powdery mildew, as it can spread the disease.