Tansy in Zone 7A — Midwest

Tansy is a worthwhile addition to any Midwest garden. Its insect-repelling properties make it a great companion plant, especially with our fertile soil and adequate summer heat. Plus, those bright yellow flowers add a cheerful touch to the landscape.

Midwest weather can be unpredictable, with cold winters and variable springs. But with a 193-day growing season, you'll find Tansy is easy to get established. Just keep an eye on those late frosts and be prepared for summer heat spells.

Starting Tansy indoors is an option, but direct sowing is often just as successful here in the Midwest. If you choose to start indoors, begin in early to late February, about six weeks before you plan to transplant. Use seed trays and provide warmth and light for best germination.

Bottom watering is a great way to keep the seedlings evenly moist without disturbing the delicate roots. Given our moderate-to-late springs, starting indoors gives you a bit of a head start.

Transplant your Tansy seedlings outdoors in late March through late April. This gives them time to establish before the full force of summer heat arrives. Before transplanting, harden off the seedlings by gradually exposing them to outdoor conditions for about a week.

Space the plants 12-18 inches apart to allow for their clumping growth habit. Keep an eye on the weather forecast; we can still get some surprising frosts that time of year.

Direct sowing Tansy is a simple and effective method here in the Midwest. Sow seeds from late March through late July. This wide window gives you flexibility.

Prepare the soil by loosening it and ensuring it's relatively weed-free. Tansy isn't picky, but good soil contact helps with germination. Space the seeds 12-18 inches apart.

Tansy is very drought-tolerant and thrives on neglect, making it perfect for busy Midwest gardeners. Our wet summers usually provide enough rainfall, so you won't need to water frequently. Overwatering can actually make it more aggressive.

During typical Midwest summers, with moderate-to-hot heat and moderate-to-humid conditions, water only when the top two inches of soil feel dry to the touch. This is the "finger test." Aim for about half an inch of water per week if rainfall is scarce. Water at the base of the plant to avoid creating overly humid conditions around the foliage, which can encourage fungal issues.

Signs of underwatering include wilting or drooping leaves. Overwatering can cause yellowing leaves and potentially root rot. A layer of mulch, like shredded bark, can help retain moisture and suppress weeds.

Pruning Tansy is important for managing its growth and preventing unwanted spread. Deadhead the flowers regularly throughout the growing season to prevent aggressive self-seeding. This is especially important if you want to contain its spread.

In the fall, after the first frost around mid- October, cut the plant back to the ground. This helps tidy up the garden and encourages fresh growth in the spring. Remember, Tansy is vigorous, so containment might be necessary.

You can expect your first Tansy harvest from early June through late October. The button-like yellow flowers typically bloom in midsummer. Tansy is primarily used as an insect repellent, not for culinary purposes, due to potential toxicity in large amounts.

Harvest the stems and flowers as needed. Cut them carefully to avoid damaging the rest of the plant. Regular harvesting encourages continued production. As the first frost approaches in mid- October, gather any remaining foliage for drying and use as insect repellent over the winter.

Here are two common problems you might encounter with Tansy in your Midwest garden:

Invasive Growth

• What it looks like: Tansy spreading rapidly beyond its intended area, crowding out other plants.
• What causes it: Tansy is a vigorous grower and readily self-seeds. Our fertile soil in the Midwest provides ideal conditions for its spread.
• How to fix/prevent it: Contain Tansy by planting it in raised beds or using underground barriers to prevent rhizome spread. Deadhead flowers regularly to prevent self-seeding.

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: 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).

Midwest Specific Challenges: The moderate-to-hot heat and moderate-to-humid humidity of our summers can encourage rapid aphid reproduction. Our wet-summer rainfall can also contribute to the spread of Tansy if not properly contained.

Tansy makes a great companion plant for several crops in the Midwest garden. It's especially beneficial near potatoes, squash, and cucumbers because its insect-repelling properties help deter pests that commonly attack these vegetables. Its strong scent can confuse insects, protecting your crops.

It's also a good companion for raspberries, helping to repel certain raspberry pests. Avoid planting Tansy near members of the brassica family (cabbage, broccoli, kale) as it can inhibit their growth.