Calendula in Zone 9B — Texas

Calendula, with its bright, cheerful blooms, is a fantastic addition to any Texas garden. The petals are edible, adding a peppery kick to salads, and they also have medicinal properties. Plus, in our long growing season, you'll get loads of satisfaction from the continuous flowers, attracting beneficial insects to your veggie patch.

Sure, we have our challenges here in Texas, from the brutal Texas heat to unpredictable weather. But with a little planning, you can enjoy Calendula almost year-round, taking full advantage of our 308-day growing season.

Starting Calendula indoors isn't essential in our Zone 9B climate, but it can give you a head start, especially if you're aiming for that very first flush of blooms. Start your seeds indoors from early to late December, about six weeks before you plan to transplant.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm and provide plenty of light – a sunny windowsill or grow lights will do the trick. Water gently from the bottom to avoid disturbing the seeds and prevent damping off. With our early springs, getting a jump start means you can enjoy blooms even sooner.

Transplant your Calendula seedlings outdoors from late January through early March. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sun and wind.

Choose a sunny spot with well-draining soil, spacing the plants 8-12 inches apart. Keep an eye on the unpredictable weather—a late freeze can happen, so be ready to cover your seedlings if temperatures dip.

Direct sowing is a simple and effective way to grow Calendula in Texas. Sow seeds directly into the garden from late January through mid October. This gives you a huge window to work with!

Prepare the soil by loosening it and removing any weeds. Sow the seeds about ¼ inch deep and keep the soil consistently moist until they germinate. Thin seedlings to 8-12 inches apart. Direct sowing is less work, but you might have to protect seedlings from pests.

Calendula prefers moderate watering and isn't very drought-tolerant, especially in the Texas heat. During the spring and fall, when temperatures are milder and rainfall is more consistent, water deeply once or twice a week, providing about 1 inch of water each time.

During the brutal Texas heat of summer, you might need to water more frequently, possibly every other day, especially if rainfall is scarce. Stick your finger about 2 inches deep into the soil – if it feels dry, it's time to water. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases, especially with our variable humidity.

Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, such as shredded hardwood or pine straw, will help retain moisture and regulate soil temperature, which is a big help during those scorching Texas summers.

Deadheading is key to keeping your Calendula plants blooming throughout our long growing season. Regularly remove spent flowers by snipping them off just below the flower head. This encourages the plant to produce more blooms instead of putting energy into seed production.

Leave some flowers to mature towards the end of the season if you want them to self-seed. As our first frost approaches around early December, let the last flowers go to seed. You can collect the seeds for next year or simply let them drop to the ground for a volunteer crop.

You can expect your first Calendula harvest about 45 days after planting, which, depending on your planting date, can be as early as early March and continue through mid December. Harvest the flowers when they are fully open, ideally in the morning after the dew has dried.

Gently pinch or cut the flower heads from the stem, taking care not to damage the plant. Regular harvesting encourages continuous production, so the more you harvest, the more flowers you'll get. As the first frost approaches in early December, harvest any remaining flowers before they are damaged by the cold.

Here are a few common problems you might encounter with Calendula in Texas:

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: Various fungi thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

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). Also, keep an eye out for fire ants farming the aphids.

Whiteflies

• What it looks like: Tiny white, moth-like insects that fly up when disturbed. Yellowing or silvering of leaves. Sticky honeydew residue.
• What causes it: Sap-sucking insects that thrive in warm weather. They are attracted to yellow.
• How to fix/prevent it: Hang yellow sticky traps. Strong water spray can dislodge them. Insecticidal soap or neem oil can be effective. Reflective mulch can deter them.

Texas Specific Challenges: The extreme heat in Texas can stress Calendula plants, making them more susceptible to pests and diseases. Our variable humidity can also create conditions favorable for fungal diseases like powdery mildew. Unpredictable rainfall patterns mean you need to be vigilant about watering, adjusting as needed to prevent both drought stress and overwatering.

Calendula makes excellent companion plants in the Texas garden. Plant them near tomatoes and peppers to attract beneficial insects like ladybugs and lacewings, which will help control pests like aphids. Calendula also helps repel tomato hornworms.

They're also great companions for green beans. Calendula attracts pollinators, increasing bean production. Avoid planting Calendula near plants that are susceptible to powdery mildew, as they can exacerbate the problem.