Yarrow in Zone 4A — Midwest

Yarrow is a fantastic addition to any Midwest garden. It's super hardy, attracts beneficial insects like crazy, and the dried flowers add a lovely touch to arrangements, especially during those long winter months when you're missing your garden. Plus, it thrives in our fertile soil and handles the summer heat spells like a champ.

Sure, Midwest weather can be a bit unpredictable, and we've all had those springs where you're wondering if winter will ever end. But with a little planning, you can easily fit Yarrow into our 128-day growing season. It's a low-maintenance plant that rewards you with beautiful blooms.

Starting Yarrow indoors is definitely an option, but honestly, with our fertile soil and decent growing season, it's often easier to direct sow or buy starts. If you're set on starting indoors, aim for late February through mid March, about eight weeks before you'd transplant.

Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light – a grow light really helps, especially with our moderate-to-late springs. Don't forget to bottom water to keep the soil consistently moist without soaking the seedlings.

Transplanting Yarrow seedlings outdoors is best done in early to late May, after the risk of frost has passed. Make sure you harden them off first – gradually expose them to outdoor conditions for about a week.

Space the plants 12-18 inches apart in a sunny spot. Keep an eye on the weather forecast around transplant time – a late frost can still sneak up on us in the Midwest, so be ready to cover your seedlings if needed. Since Yarrow is a perennial, consider buying starts if you want flowers the first year.

Direct sowing Yarrow is a pretty straightforward method. Wait until mid May through early July, when the soil has warmed up a bit. Yarrow isn't too picky, but it likes well-drained soil.

Simply scatter the seeds lightly over the soil surface and gently press them in. Keep the soil consistently moist until the seedlings emerge. You'll want to thin them to 12-18 inches apart once they're a few inches tall.

Yarrow is one tough cookie when it comes to watering. Once established, it's very drought-tolerant, which is great for those summer heat spells we get in the Midwest. It actually prefers poor, well-drained soil, so don't overdo it.

During the first few weeks after planting, water regularly to help the roots get established. After that, back off. A good rule of thumb is to check the soil about 2 inches deep – if it's dry, it's time to water. Usually, an inch of water per week, including rainfall, is plenty. Water at the base of the plant to avoid getting the foliage wet, especially with our moderate-to-humid summers.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can lead to floppy growth and root rot. A layer of mulch around the base of the plant can help retain moisture and suppress weeds – just be sure to leave some space around the stem to prevent rot.

Pruning Yarrow is pretty simple. The main thing is to deadhead the spent flowers throughout the season. This encourages a second flush of blooms and keeps the plant looking tidy.

Just snip off the flower heads below the lowest set of leaves. Towards the end of the season, after the first frost around mid- September, cut the plant back to its basal foliage. Since Yarrow can be a bit aggressive, divide the plants every 2-3 years to keep them from taking over your garden.

You can expect your first Yarrow harvest from mid July through late September, depending on when you planted. The best time to harvest the flowers for drying is when they're fully open and the color is at its peak.

Simply cut the stems just above a set of leaves. To encourage continued production, keep harvesting the flowers regularly. As the first frost approaches in mid- September, harvest any remaining flowers you want to dry. Yarrow won't ripen off the vine.

Yarrow is generally a pretty easy plant to grow, but here are a few common problems you might encounter in the Midwest:

Spreading Aggressively

• What it looks like: Yarrow starts popping up everywhere, even where you didn't plant it. It can quickly take over garden beds and crowd out other plants.
• What causes it: Yarrow spreads through rhizomes (underground stems). Our fertile soil in the Midwest provides ideal conditions for it to spread rapidly.
• How to fix/prevent it: Plant Yarrow in containers or raised beds to contain its spread. Divide the plants every 2-3 years to control growth. Be diligent about removing unwanted shoots as they appear.

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: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it (unlike most fungi).
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning out crowded growth. Remove and dispose of affected leaves. Neem oil or potassium bicarbonate sprays can help. A 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. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Knock them off with a strong stream of water. Encourage beneficial insects like ladybugs and lacewings (natural predators). Insecticidal soap can be used for heavy infestations. Avoid excess nitrogen fertilizer (it attracts them).

Midwest Specific Challenges: Our combination of moderate-to-hot heat, moderate-to-humid humidity, and wet-summer rainfall can create favorable conditions for powdery mildew and aphid infestations. The fertile soil encourages aggressive spreading. Regular monitoring and preventative measures are key to keeping your Yarrow healthy and under control.

Yarrow makes a great companion plant in the Midwest garden. It attracts beneficial insects like ladybugs and hoverflies, which prey on pests like aphids and other unwanted critters that can plague our tomatoes and peppers.

Planting Yarrow near herbs can also be beneficial, as it's thought to enhance their essential oil production. Plus, Yarrow is a good neighbor for strawberries, as it can help repel some common strawberry pests. Avoid planting Yarrow near plants in the brassica family (cabbage, broccoli, etc.), as it can sometimes attract cabbage moths.