Yarrow in Zone 9A — Florida

Yarrow is a fantastic addition to any Florida garden. Its feathery foliage and clusters of cheerful flowers bring beauty and attract beneficial insects, which are always welcome in our yards. Plus, you can dry the flowers for arrangements, adding a touch of your garden's bounty to your home.

Our Florida gardening calendar is different, and while the summer can be a bit slow due to the heat and humidity, yarrow is surprisingly resilient. With our long growing season of 327 days, you have plenty of time to get it established and enjoy its benefits, especially planting in fall and harvesting in winter.

Starting yarrow indoors isn’t essential here in Zone 9A, but it can give you a head start, especially if you're after blooms in the first year. Starting indoors is most useful for ensuring you get the exact variety you want.

If you choose to start indoors, sow your seeds from mid November through early December, about 8 weeks before you'd like to transplant. Use seed trays with a good seed-starting mix and keep them warm and consistently moist. Bottom watering can help prevent damping-off, a common problem with seedlings. Remember that our spring is reversed – starting early gives you a jump before the heat of summer arrives.

Transplanting yarrow is best done from mid January through mid February. This gives the plants time to establish before the heat of summer hits.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Choose a sunny spot with well-drained soil and space the plants 12-18 inches apart. Even in January and February, you might get a warm spell, so keep an eye on newly transplanted seedlings and water them if the soil dries out quickly. Buying starts gets you blooms in the first year.

Direct sowing yarrow is a simple and effective method in Florida, given our long growing season. The best time to direct sow is from early February through early October.

Prepare the soil by loosening it and removing any weeds. Yarrow prefers well-drained soil, so amend with some compost if you have heavy clay. Sow the seeds thinly and keep the soil consistently moist until they germinate. Space the plants 12-18 inches apart once they're established.

Yarrow is very drought-tolerant once established, making it a great choice for Florida gardens. However, getting the watering right, especially in our humid climate, is key.

During the cooler, drier months (late fall through early spring), water only when the top 2 inches of soil feel dry to the touch – use the "finger test." Aim for about 1 inch of water per week, including rainfall. In the hot and humid summer months, be extra cautious. Our frequent summer rains often provide enough moisture, so avoid overwatering.

Water at the base of the plant rather than overhead to minimize fungal diseases, which thrive in our humid conditions. Signs of underwatering include wilting leaves, while overwatering can lead to floppy growth and root rot. A light layer of mulch, like pine straw, can help retain moisture without creating a soggy environment.

Pruning yarrow is straightforward and helps encourage continued blooming. The main task is deadheading – removing spent flowers.

Deadhead regularly throughout the growing season, from spring through fall, to encourage a second flush of blooms. Simply snip off the flower heads just below the bloom. In late fall, as our first frost approaches around late December, cut the plant back to its basal foliage (the leaves at the base of the plant). Yarrow can be aggressive, so divide clumps every 2-3 years to keep it in check.

You can expect your first yarrow harvest in early April through early January, about 65 days after planting. The best time to harvest the flowers for drying is when they are fully open and the color is vibrant.

To harvest, cut the stems just above a leaf node. Gather the stems into small bundles and hang them upside down in a cool, dark, and dry place to dry. Regular harvesting encourages continued production, so keep cutting those flowers! Even as our first frost approaches, you can still harvest any remaining blooms.

Yarrow is generally easy to grow, but here are a few common problems in Florida:

Spreading Aggressively

• What it looks like: Yarrow can quickly take over garden beds, spreading via rhizomes (underground stems).
• What causes it: Our long growing season allows yarrow ample time to spread.
• How to fix/prevent it: Plant in containers or use edging to contain the spread. Regularly divide clumps to prevent overcrowding.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves and stems. Leaves may curl, yellow, and die.
• What causes it: Fungal disease thriving in warm days, cool nights, and moderate humidity. Dry leaf surfaces favor it, which can happen even in our humid climate if the plants are crowded.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays can help. Milk spray (1 part milk to 9 parts water) is surprisingly effective.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Populations explode in warm weather.
• 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.

Florida Specific Challenges: Our hot heat, very-high humidity, and wet-summer rainfall can exacerbate fungal diseases like powdery mildew. Ensure good air circulation and avoid overhead watering to minimize these problems. Also, consider nematode-resistant varieties if nematodes are a known issue in your soil.

Yarrow is a great companion plant for many vegetables and herbs in the Florida garden.

It's a good companion to tomatoes and peppers because it attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests that can damage these crops. It also benefits herbs by attracting pollinators and deterring unwanted insects. Strawberries also benefit from the presence of yarrow, as the beneficial insects it attracts can help control pests that attack strawberries.

I wouldn't recommend planting it near anything that might be overwhelmed by Yarrow's somewhat aggressive spreading habit.