Calendula in Zone 8B — Southeast

Calendula is a fantastic addition to any Zone 8B garden here in the Southeast. The bright, cheerful flowers are edible, adding a peppery kick to salads, and they also have medicinal properties. Plus, they attract pollinators to your garden, which is always a win with our long summer growing season.

Of course, gardening in the Southeast comes with its own set of challenges, like our hot, humid summers and clay soil. But don't let that scare you! With a little planning and the right timing, you can successfully grow calendula and enjoy its beauty and benefits throughout our 255-day growing season.

Starting calendula indoors isn't strictly necessary here in the Southeast, but it can give you a head start, especially if you're eager for those early blooms. If you want to go this route, start your seeds indoors from early to late January, about six weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light – a simple shop light works well. Water gently, and consider bottom watering to avoid damping off, a common problem in our humid climate. Remember, our spring is moderate, so you'll want to get a jump start where you can.

Transplant your calendula seedlings outdoors from late February through early April, once the danger of a hard freeze has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Southeast's temperature swings.

Choose a spot with full sun to partial shade and space the plants 8-12 inches apart. Keep an eye on the weather forecast – a late cold snap can still happen, so be ready to cover your young plants if needed.

Direct sowing calendula is a simple and effective method for us here in the Southeast. You can direct sow from late February through late September, giving you a wide window to work with. The seeds germinate best when the soil temperature is around 65-70°F.

Prepare your soil by loosening it and removing any weeds. Sow the seeds about ¼ inch deep and space them 8-12 inches apart. Keep the soil consistently moist until the seedlings emerge. Direct sowing is great, but remember, the plants will take a bit longer to mature compared to transplants.

Calendula needs moderate watering to thrive in our Zone 8B gardens. While it can tolerate some drought, consistent moisture is key, especially during our hot, humid summers. However, calendula prefers cooler weather and may go dormant in the peak of our summer heat if it gets too dry.

During the spring and fall, when temperatures are milder, water deeply about once a week, providing around 1 inch of water. In the heat of summer, you might need to water every few days, especially if we're not getting our usual afternoon thunderstorms. Always check the soil moisture before watering – stick your finger about 2 inches deep. If it feels dry, it's time to water.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so watch out for yellowing leaves and a soggy soil. A layer of mulch around the plants can help retain moisture and suppress weeds, which is extra helpful with our clay soil.

Regular pruning, or deadheading, is essential for keeping your calendula plants blooming throughout the season. Simply pinch or cut off the spent flowers just below the flower head. This encourages the plant to produce more blooms instead of focusing on seed production.

Deadhead throughout the growing season, from spring until the first frost around mid- November. If you want the plants to self-seed, leave a few flowers to mature and dry on the plant. At the end of the season, you can cut back the plants to the ground after they've finished blooming.

You can expect your first calendula harvest about 45 days after planting. Here in the Southeast, that means you'll likely be harvesting from early April through late November. Harvest the flowers when they are fully open, ideally in the morning after the dew has dried.

Gently pluck the flower heads from the plant, being careful not to damage the surrounding foliage. The petals are what you're after, and they're ready to use fresh or dried. Continued harvesting encourages more blooms, so keep at it! As the first frost approaches in mid- November, harvest any remaining flowers to make the most of your plants.

Here are some common problems you might encounter with calendula in the Southeast:

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves, stems, and sometimes flower buds. Leaves may curl, yellow, and eventually die.
• What causes it: Various fungi thrive in our warm days, cool nights, and moderate to high humidity. Surprisingly, dry leaf surfaces actually favor powdery mildew, unlike most fungal diseases.
• How to fix/prevent it: Improve air circulation by spacing your plants properly and pruning to open up the canopy. Remove and dispose of any affected leaves. Neem oil or potassium bicarbonate sprays can help control the spread. A milk spray (1 part milk to 9 parts water) is also surprisingly effective. Look for powdery mildew-resistant calendula varieties.

Aphids

• What it looks like: Clusters of tiny, soft-bodied insects (green, black, or white) on stems and undersides of leaves. You might also notice a sticky "honeydew" residue and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather. Ant colonies often "farm" them for their honeydew.
• How to fix/prevent it: A strong spray of water from the hose can knock aphids off the plants. Encourage natural predators like ladybugs and lacewings. Insecticidal soap is effective for heavy infestations. Neem oil also works systemically. Avoid over-fertilizing with nitrogen, as this attracts aphids.

Whiteflies

• What it looks like: Tiny, white, moth-like insects that flutter around when disturbed. Yellowing or silvering leaves. Sticky honeydew residue.
• What causes it: Whiteflies are sap-sucking insects that thrive in warm, humid conditions. They can quickly build up large populations.
• How to fix/prevent it: Yellow sticky traps can help catch adult whiteflies. Spray plants with insecticidal soap or neem oil, making sure to cover the undersides of the leaves. Remove heavily infested leaves. Encourage natural predators like lacewings and parasitic wasps.

Southeast Specific Challenges: Our hot, humid summers create ideal conditions for fungal diseases like powdery mildew. The humidity also makes aphid and whitefly infestations more likely. Regular monitoring and preventative measures are key to keeping your calendula healthy.

Calendula makes a great companion plant for several vegetables in the Southeast garden. Plant them near tomatoes and peppers; calendula attracts beneficial insects that prey on pests that bother these veggies.

Calendula also does well planted near green beans. Avoid planting near members of the cabbage family, as they can compete for nutrients.