Calendula in Zone 9A — Texas

Calendula is a fantastic addition to any Texas garden. The bright, cheerful flowers are edible and medicinal, adding a pop of color to your garden and your plate. Plus, in Zone 9A, you can often enjoy two harvests from one planting thanks to our long growing season.

Sure, we deal with unpredictable weather and the brutal Texas heat. But with a little planning, you can easily grow Calendula. Our long 293-day growing season gives you plenty of opportunities to get it right.

Starting Calendula indoors in the Texas can give you a jump start, especially if you want early blooms. Sow seeds indoors from mid December through early January, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and keep them warm and well-lit – a sunny windowsill or grow lights will do the trick.

Consider bottom watering your seedlings to encourage strong root growth and prevent damping off. With our early spring-like warm spells, getting a head start indoors can be beneficial, but direct sowing works well too.

Transplant your Calendula seedlings outdoors from early February through mid March. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sunshine and variable temperatures.

Space your plants about 8-12 inches apart in well-draining soil. Keep an eye on the weather forecast – those late-season cold snaps can still surprise us, so be ready to cover your seedlings if necessary.

Direct sowing Calendula is a breeze in the Texas. Sow seeds directly into your garden from early February through early October. This gives you a long window to get them established.

Prepare the soil by loosening it and removing any weeds. Scatter the seeds and lightly cover them with soil, keeping them moist until they germinate. Direct sowing is easy, but remember that seedlings might be more vulnerable to pests like fire ants.

Calendula needs moderate watering to thrive in the Texas climate. During the cooler months of spring and fall, aim for about 1 inch of water per week, either from rainfall or irrigation. In the heat of summer, you might need to increase that to 1.5 inches, especially if rainfall is scarce.

Use the finger test: 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 plants to avoid wetting the foliage, which can encourage fungal diseases in our variable humidity.

Overwatering can lead to root rot, while underwatering can cause wilting and stunted growth. Watch for yellowing leaves (overwatering) or drooping (underwatering). A layer of mulch around your plants helps retain moisture and suppress weeds, which is especially helpful during our hot, dry spells.

Deadheading is key to keeping your Calendula blooming throughout the long Texas growing season. Regularly remove spent flowers to encourage the plant to produce more buds. Simply snip off the flower heads just below the bloom.

Leave some flowers to mature if you want the plant to self-seed. Towards the end of the season, around early December when we start to see frost, you can let the last flowers go to seed to ensure you have volunteers next year.

You can expect your first Calendula harvest about 45 days after planting, typically from mid March through mid December in the Texas. Harvest the flowers when they are fully open, ideally in the morning after the dew has dried. The petals are edible and medicinal.

To harvest, simply snip off the flower heads with scissors or pruning shears. Be gentle to avoid damaging the plant. Regular harvesting encourages continuous production, so keep picking those blooms!

As the first frost approaches in early December, harvest any remaining flowers. You can dry them for later use.

Here are some common problems you might encounter growing Calendula in the Texas:

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves and stems. Leaves may curl, yellow, and die.
• What causes it: Fungi thrive in warm days, cool nights, and moderate humidity, which we often experience in spring and fall. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves promptly. Neem oil or potassium bicarbonate sprays can help. A milk spray (1 part milk to 9 parts water) can also be effective.

Aphids

• What it looks like: Clusters of tiny insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: A strong water spray can knock them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap is effective for heavy infestations. Neem oil works systemically.

Whiteflies

• What it looks like: Tiny, white, moth-like insects that fly up when disturbed. Yellowing or silvering leaves. Sticky honeydew residue.
• What causes it: These sap-sucking insects thrive in warm climates and can quickly infest plants.
• How to fix/prevent it: Yellow sticky traps can capture adults. Strong water sprays can dislodge them. Insecticidal soap or neem oil can control infestations.

Texas Specific Challenges: The hot-to-extreme heat of our Texas summers can stress Calendula, making it more susceptible to pests and diseases. Variable humidity can also create favorable conditions for fungal problems like powdery mildew. Unpredictable rainfall can make it challenging to maintain consistent soil moisture.

Calendula makes a great companion plant in the Texas garden. It attracts beneficial insects that can help protect your other crops.

Good companions include:

• Tomatoes: Calendula attracts beneficial insects like ladybugs and hoverflies, which prey on tomato pests like aphids and whiteflies.
• Peppers: Similar to tomatoes, Calendula helps protect peppers from pests.
• Green Beans: Calendula can help repel bean beetles, which can be a nuisance in the Texas garden.

Avoid planting Calendula near any plants susceptible to powdery mildew, as it can exacerbate the problem.