Tansy in Zone 7B — Southeast

Tansy is a worthwhile addition to your Southeast garden, primarily for its insect-repelling properties. It's not something you'll be cooking with, but it can help keep pests away from your more edible plants. Plus, the bright yellow flowers add a nice pop of color to the landscape during our long summer.

We all know the challenges of gardening in the Southeast: the hot, humid summers and our infamous clay soil. However, Tansy is quite forgiving. With our long 235-day growing season, you have plenty of time to get it established and reap the benefits.

Starting Tansy indoors is an option, especially if you're eager to get a head start. Sow seeds indoors from mid January through early February, about six weeks before the typical transplanting window. This can be helpful if you want larger plants going into the ground.

Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light. A heat mat can speed up germination. Water from the bottom to prevent damping off. Our moderate spring weather means you don't *have* to start indoors, but it's a viable choice.

Once the danger of frost has passed, usually from early March through early April, you can transplant your Tansy seedlings outdoors. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space the plants 12-18 inches apart. Keep an eye on the weather forecasts around transplant time; a late cold snap can still happen.

Direct sowing Tansy is a simple and effective method in our climate. You can sow seeds directly into the garden from early March through mid August. This gives you a long window to get it going.

Prepare the soil by loosening it and removing any weeds. Tansy isn't too picky, but well-draining soil is always best, even if we're dealing with clay. Scatter the seeds lightly and cover them with a thin layer of soil.

Tansy thrives on neglect, which is good news for us Southeast gardeners dealing with our hot, humid summers. Once established, it's very drought-tolerant. Overwatering or over-fertilizing can actually make it more aggressive, so go easy.

During the spring and fall, when rainfall is less frequent, check the soil moisture with the "finger test." Stick your finger about two inches into the soil. If it feels dry, it's time to water. Aim for about an inch of water per week, especially during dry spells. During our wet-summer months, you likely won't need to water at all. Water at the base of the plant to avoid creating a humid environment around the foliage, which can encourage fungal diseases.

Signs of underwatering include wilting leaves, while overwatering can lead to yellowing leaves and root rot. A layer of mulch can help retain moisture in the soil and suppress weeds, just be sure it's not piled up against the stem.

Deadheading is key to keeping Tansy from becoming too aggressive in your garden. Remove the spent flower heads regularly throughout the growing season to prevent self-seeding. This is especially important if you're trying to contain it.

You can cut back the entire plant in the fall after the first frost around early November. This helps tidy up the garden and encourages new growth in the spring.

You can expect your first harvest of Tansy around mid May through mid November, about 75 days after planting. Tansy is harvested for its insect-repelling properties, not for culinary use. The button-like yellow flowers are a good indicator that the plant is mature enough to harvest.

To harvest, simply cut the stems as needed. Regular harvesting encourages continued production. As the first frost approaches in early November, you can harvest the remaining stems and dry them for later use.

Here are a couple of common issues you might encounter with Tansy in the Southeast:

Invasive Nature

• What it looks like: Tansy spreads rapidly, popping up in unwanted areas of your garden.
• What causes it: It's a vigorous self-seeder and can also spread through underground rhizomes.
• How to fix/prevent it: Contain it by planting it in pots or using physical barriers sunk into the ground. Deadhead regularly to prevent seed dispersal.

Aphids

• What it looks like: Clusters of tiny insects (green, black, or white) on stems and leaf undersides. You might also see sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects thrive in warm weather and can quickly multiply.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage beneficial insects like ladybugs. For heavy infestations, use insecticidal soap or neem oil. Avoid over-fertilizing with nitrogen, as it attracts aphids.

Southeast Specific Challenges

Our hot, humid summers can exacerbate both of these problems. The humidity can create a favorable environment for aphids, and the long growing season gives Tansy ample time to spread. Keep a close eye on your plants and take action quickly to prevent these issues from getting out of hand.

Tansy can be a helpful companion plant in the garden. It's said to repel certain pests, benefiting plants like potatoes, squash, and cucumbers. The strong scent can deter insects that might otherwise damage these crops. It's also said to benefit raspberries.

Avoid planting Tansy near plants, as its allelopathic properties might inhibit their growth.