Feverfew in Zone 5A — Mountain West

Feverfew is a fantastic addition to any Mountain West garden. Its cheerful, daisy-like flowers brighten up the landscape, attract beneficial insects, and have a history as a traditional herbal remedy. The cool nights even in summer and intense sunlight seem to amplify the flavor and potency of many herbs, and Feverfew is no exception.

Our high altitude gardening here presents unique challenges, like intense UV, alkaline soil, and a short season. But with a 138-day growing season, Feverfew is a manageable and rewarding plant to grow if you plan your timing well.

Starting Feverfew indoors gives you a head start on our short growing season, but it's not always necessary. If you're aiming for the earliest possible blooms, or want to guarantee a harvest before the first frost, indoor starting is a good option.

Begin in early to late March, about eight weeks before you plan to transplant. Use seed trays with a good seed-starting mix, provide warmth (a heat mat is helpful), and ensure bright light. Bottom watering is ideal to prevent damping off and keep the seedlings evenly moist. Remember, our late springs mean the indoor growing period can sometimes feel long, so be prepared to pot up your seedlings if they outgrow their initial containers.

Transplanting Feverfew outdoors is best done in early to late May, after the last expected frost. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler nights that are typical here.

Choose a sunny spot with well-drained soil, and space the plants 12-15 inches apart. Keep an eye on the weather forecast – a late frost or unexpected hail can still occur, so be ready to cover your young plants if needed.

Direct sowing Feverfew is a straightforward option, especially if you're not in a rush for early blooms. Sow seeds directly into the garden anytime from early May through early July. The soil temperature should be consistently above 60°F for optimal germination.

Prepare the soil by loosening it and removing any weeds or debris. Scatter the seeds lightly over the surface, and gently press them into the soil. Keep the soil consistently moist until the seedlings emerge. Thin the seedlings to 12-15 inches apart once they are a few inches tall. Direct sowing is convenient, but remember that the plants will take longer to mature compared to transplants.

Feverfew is wonderfully drought-tolerant once established, making it a great choice for our dry Mountain West climate. While young plants need consistent moisture, mature plants prefer drier conditions. Overwatering is a common mistake that can lead to root rot, especially in our alkaline soil.

During the peak of summer, when temperatures can reach around 85°F, water deeply about once a week, providing around 1 inch of water. Use the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. In spring and fall, reduce watering frequency as temperatures cool. Water at the base of the plant to avoid wetting the foliage, which helps prevent fungal diseases in our low-humidity environment.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can cause yellowing leaves and mushy stems. A layer of mulch around the base of the plants helps to retain moisture in the soil and suppress weeds, which is especially useful given our intense sun.

Pruning Feverfew is simple and helps to encourage continuous blooming throughout the season. The key is to deadhead spent flowers regularly. This prevents the plant from putting energy into seed production and promotes new growth.

Throughout the growing season, snip off any faded or dried-up flower heads just below the flower. After the main flowering period in late summer, you can cut the plant back by about one-third to encourage a second flush of blooms. Be aware that Feverfew self-seeds aggressively if you let the flowers go to seed, so deadheading is important if you want to control its spread. As the first frost approaches in late September, you can leave the remaining flowers to dry on the plant, providing winter interest and seed for the following year (if you want it!).

You can expect your first Feverfew harvest in mid-July through early October, about 70 days after planting. The best time to harvest is when the small, daisy-like flowers are in full bloom. These flowers are the part traditionally used for herbal remedies.

To harvest, simply snip off the flower heads with a pair of scissors or pruning shears, taking care not to damage the rest of the plant. Regular harvesting encourages continued production, so don't be afraid to cut liberally. As the first frost approaches in late September, you can harvest the remaining flowers, even if they are not fully open, and dry them for later use. Feverfew doesn't ripen off the vine, so only harvest flowers that are fully formed.

Here are some common issues you might encounter with Feverfew in the Mountain West:

Self-seeds Prolifically

• What it looks like: Numerous Feverfew seedlings popping up in unwanted areas of your garden.
• What causes it: Letting the flowers go to seed allows them to spread easily. Our dry climate aids in seed dispersal.
• How to fix/prevent it: Deadhead spent flowers regularly before they form seeds. Remove unwanted seedlings promptly. Consider growing Feverfew in containers to limit its spread.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects thrive in warm weather. Ant colonies may farm them for honeydew. The intense UV in our region can stress plants, making them more susceptible.
• 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. Avoid excess nitrogen fertilizer (it attracts them).

Leaf Miners

• What it looks like: Winding, pale trails or blotches within the leaves.
• What causes it: Larvae of small flies tunnel between the leaf surfaces, feeding on the tissue.
• How to fix/prevent it: Remove and destroy infested leaves. Use row covers to prevent adult flies from laying eggs on the plants. Beneficial nematodes can help control leaf miner larvae in the soil.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall can actually benefit Feverfew by reducing the risk of fungal diseases. The intense sun, however, can stress the plants if they are not properly watered, making them more susceptible to pests. Monitor your plants closely and adjust your care as needed.

Feverfew makes a great companion plant in the Mountain West garden. It benefits tomatoes by repelling certain pests that can damage the tomato plants. Roses also benefit from Feverfew, as it deters aphids and other insects that can attack roses.

Many herbs, such as rosemary and sage, are good companions for Feverfew, as they share similar growing requirements and can help to attract beneficial insects to the garden. Avoid planting Feverfew near plants that require consistently moist soil, as its drought-tolerant nature means it prefers drier conditions.