Tansy in Zone 8B — Southeast

Tansy is a worthwhile addition to any Southeast garden, mainly for its insect-repelling properties. It's especially useful around here, given our long summer and the constant battle with pests like Japanese beetles. Plus, there's a certain satisfaction in growing something that helps keep your other plants healthy.

Now, we all know gardening in the Southeast comes with challenges. The humidity and potential for fungal diseases are real, but Tansy is pretty resilient. With our long growing season of around 255 days, you'll have plenty of time to get it established and reap the benefits.

Starting Tansy indoors in the Southeast is possible but honestly not usually necessary. Our moderate springs and long growing season make direct sowing a good option. However, if you want a head start, you can begin indoors in early to late January, about six weeks before the typical transplanting window.

Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light, either with a grow light or a sunny windowsill. Don't forget to water from the bottom to avoid damping off, a common problem in our humid climate.

Transplanting Tansy outdoors in the Southeast should be done in late February through late March. Before you put them in the ground, harden them off by gradually exposing them to outdoor conditions for about a week. This will help them adjust to the sun and temperature swings we often see during that time.

Plant them 12-18 inches apart in well-draining soil. Keep an eye on the weather forecast, as a late frost can still happen. If a freeze is predicted, cover your young plants to protect them.

Direct sowing Tansy is a simple and effective method in our Southeast climate. Aim to sow seeds from late February through late August. This gives you a wide window, thanks to our long growing season.

Prepare the soil by loosening it and removing any weeds. Tansy isn't too picky, but well-draining soil is always best, especially with our frequent afternoon thunderstorms. Sow the seeds shallowly and keep the soil moist until they germinate. Thin the seedlings to 12-18 inches apart once they're a few inches tall.

Tansy is very drought-tolerant and thrives on neglect, which is a blessing in our hot and humid Southeast summers. Overwatering is a far bigger problem than underwatering with this plant. In fact, too much water can make it even more aggressive.

During the spring, when rainfall is generally consistent, you likely won't need to water at all unless we're experiencing an unusually dry spell. During the heat of the summer, check the soil before watering. Stick your finger about two inches deep; if it's dry, give the plants a good soak. Aim for about an inch of water per week, but only if needed. Remember, we get a lot of rainfall in the summer, so let the weather be your guide.

Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid environment. Signs of underwatering include wilting leaves, while yellowing leaves can indicate overwatering. A layer of mulch around the base of the plants can help retain moisture and suppress weeds, but don't overdo it – Tansy prefers drier conditions.

Pruning Tansy is primarily about managing its growth and preventing it from becoming too invasive. The main thing you'll want to do is deadhead the flowers as they fade. This prevents the plant from self-seeding and spreading aggressively, which is important in our region where it can easily take over.

Throughout the growing season, remove any dead or damaged foliage. Then, in the fall, after our first frost around mid- November, cut the plant back to the ground. This helps tidy things up and encourages new growth in the spring.

In the Southeast, you can expect your first Tansy harvest from early May through late November. Tansy is ready to harvest when it has its button-like yellow flowers, which usually bloom in midsummer. Remember, Tansy is primarily used as an insect repellent and isn't suitable for culinary purposes due to its potential toxicity in large amounts.

To harvest, simply cut the stems with flowers using clean shears. Be mindful not to damage the rest of the plant. Regular harvesting encourages continued production throughout the growing season. As our first frost approaches in mid- November, you can harvest the remaining foliage and dry it for winter use as an insect repellent.

Tansy is generally a low-maintenance plant, but there are a couple of potential problems to watch out for in the Southeast.

Invasive Growth

• What it looks like: Tansy spreads rapidly, forming dense clumps and potentially overtaking other plants in your garden.
• What causes it: Tansy is a vigorous grower that readily self-seeds. Our long growing season in the Southeast gives it plenty of time to spread.
• How to fix/prevent it: Plant Tansy in a contained area, such as a raised bed or surrounded by a physical barrier that extends at least 12 inches into the ground. Deadhead flowers regularly to prevent self-seeding. Remove unwanted seedlings promptly.

Aphids

• What it looks like: Clusters of tiny, soft-bodied insects (green, black, or white) on stems and leaf undersides. You might also see a sticky honeydew residue and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that thrive in warm weather. Populations can explode quickly. Ants may also be present, farming the aphids for honeydew.
• How to fix/prevent it: Knock aphids off plants with a strong spray of water. Encourage natural predators like ladybugs and lacewings. For heavy infestations, use insecticidal soap or neem oil. Avoid over-fertilizing with nitrogen, as this attracts aphids.

Southeast Specific Challenges: Our hot, humid summers and wet-summer rainfall can exacerbate both of these problems. The humidity can encourage fungal diseases if aphids are present, and the long growing season gives Tansy ample time to spread aggressively. Be proactive in managing these issues to keep your Tansy and your garden healthy.

Tansy can be a great companion plant for certain vegetables and fruits in the Southeast garden. It's known to repel certain pests, which can benefit nearby plants.

Good companions for Tansy include potatoes, squash, cucumbers, and raspberries. Tansy helps repel potato beetles, squash bugs, and cucumber beetles. It can also deter raspberry beetles, protecting your raspberry crop.

Avoid planting Tansy near brassicas (cabbage, broccoli, cauliflower), as it can inhibit their growth. Also, be cautious about planting it near herbs like mint, as Tansy can be invasive and outcompete them.