Tansy in Zone 7B — Desert Southwest

Tansy is a fantastic addition to your Desert Southwest garden, not for the dinner table, but as a natural insect repellent. Its strong scent can help deter pests from your other plants, and its cheerful yellow flowers bring a touch of brightness to our arid landscape. Plus, it's incredibly low-maintenance, a huge win in our climate.

Our extreme heat and alkaline soil can be tough on many plants, but Tansy thrives with minimal care. With our long 245-day growing season, you have plenty of time to get it established and reap its benefits. Timing is key, and we'll get into the best planting windows to ensure your Tansy thrives.

Starting Tansy indoors is an option, but honestly, it's usually not necessary here in the Desert Southwest. Our long growing season gives us plenty of time to direct sow. However, if you want a head start, you can begin indoors from mid January through early February, about six weeks before our last frost.

Use seed trays or small pots filled with well-draining potting mix. Keep the soil consistently moist, watering from the bottom to avoid damping off, and provide plenty of light. Remember our spring warmth can be a bit unexpected, so be ready to harden off your seedlings if we get an early warm spell.

Transplanting Tansy outdoors should be done from early to late March, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense Desert Southwest sun and temperature fluctuations.

Choose a sunny or partially shaded spot and space your Tansy plants 12-18 inches apart. Be mindful of late cold snaps that can sometimes surprise us. If a frost is predicted, cover your transplants with frost cloth to protect them.

Direct sowing Tansy is a simple and effective method in our region, thanks to our long growing season. You can direct sow from early March through mid August. This gives you a wide window to get seeds in the ground.

Prepare your soil by loosening it and removing any rocks or debris. Tansy isn't picky, but well-draining soil is always best, especially with our occasional monsoon moisture. Sow seeds 12-18 inches apart and keep the soil consistently moist until germination.

Tansy is exceptionally drought-tolerant, making it a perfect fit for Desert Southwest gardens where water conservation is crucial. Once established, it thrives on neglect, so resist the urge to overwater! In fact, too much water can make it even more aggressive.

During the hottest part of the summer, when temperatures soar above 100°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. During the cooler spring and fall months, you can reduce watering to once every two weeks or even less, especially with monsoon moisture.

Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases. Signs of underwatering include wilting or drooping leaves. Overwatering can lead to yellowing leaves and root rot. A layer of gravel mulch around the base of the plant can help retain moisture and suppress weeds, which is helpful in our arid climate.

Pruning Tansy is essential to keep it from becoming too aggressive in your Desert Southwest garden. Deadhead spent flowers regularly throughout the growing season to prevent self-seeding. This is especially important if you want to keep it contained.

In the fall, after the first frost around mid- November, cut back the entire plant to a few inches above the ground. This helps rejuvenate the plant for the next growing season. Because Tansy is vigorous, consider growing it in containers or using underground barriers to prevent it from spreading too much.

You can expect your first harvest of Tansy foliage starting in mid May and continuing through late November. Tansy is primarily grown for its insect-repelling properties, not for culinary use, as it can be toxic in large amounts. The button-like yellow flowers typically bloom in midsummer.

Harvest the foliage by cutting stems as needed, leaving enough foliage for the plant to continue growing. Regular harvesting encourages new growth and keeps the plant compact. As the first frost approaches in mid- November, you can harvest the remaining foliage and dry it for use as an insect repellent throughout the winter.

Tansy is generally a hardy plant, but here are a couple of problems you might encounter in the Desert Southwest:

Invasive Growth

• What it looks like: Tansy spreading rapidly beyond its intended area, popping up in unwanted places in your garden.
• What causes it: Tansy is a vigorous self-seeder, and our long growing season allows it ample time to spread. The seeds are easily dispersed by wind and water.
• How to fix/prevent it: Contain Tansy by growing it in pots or using underground barriers. Deadhead flowers regularly to prevent seed production. Remove unwanted plants promptly.

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: Aphids thrive in warm weather, and our long, hot summers can lead to rapid population explosions. They suck sap from the plant, weakening it.
• How to fix/prevent it: Knock them off with a strong spray of water. Encourage natural predators like ladybugs. Use insecticidal soap or neem oil for heavy infestations. Avoid excess nitrogen fertilizer, which attracts them.

Desert Southwest Specific Challenges: Our extreme heat and arid conditions can stress Tansy, making it more susceptible to pest infestations. The monsoon season can also lead to fungal diseases if the plant is not well-drained. Ensure good air circulation and avoid overwatering to minimize these issues.

Tansy makes a good companion for several plants in your Desert Southwest garden. It repels potato beetles, making it a great companion for potatoes. It also deters squash bugs and cucumber beetles, benefiting squash and cucumbers.

Tansy is also said to deter certain pests from raspberries. Avoid planting Tansy near brassicas like cabbage and broccoli, as it can attract cabbage moths. Keep it away from herbs like basil and mint, as it can inhibit their growth.