Calendula in Zone 6B — Texas

Calendula is a fantastic addition to any Texas garden. The cheerful blooms brighten up the space, and the petals are edible, adding a peppery zest to salads. Plus, they're known for their medicinal properties. In our long growing season, you can enjoy Calendula's beauty and usefulness for months.

Our Texas weather can be unpredictable, with periods of extreme heat and occasional freezes. But don't worry, Calendula is surprisingly adaptable, and with a bit of planning, you can make the most of our 230-day growing season to enjoy a thriving patch.

Starting Calendula indoors isn't essential, but it can give you a jumpstart, especially for an early spring bloom. If you want to get a head start, sow seeds indoors from late January through mid February, about six weeks before you plan to transplant them outside.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water and let the soil absorb it from below. This helps prevent damping-off. Place the trays in a warm spot and provide plenty of light, either from a sunny window or a grow light. With our early springs, starting indoors can get you blooms even sooner.

Once the weather starts to warm up in mid March through late April, and the danger of hard frost has passed, it's time to transplant your Calendula seedlings outdoors. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. Start with a few hours of shade and slowly increase sun exposure each day.

Plant them 8-12 inches apart in well-drained soil. Keep an eye on the forecast, as we can still get some unexpected cool snaps during this time. If a freeze is predicted, cover your young plants to protect them.

Direct sowing Calendula is easy and effective, especially with our long growing season. You can sow seeds directly into the garden from mid March through mid September.

Choose a spot with full sun to partial shade. Prepare the soil by loosening it and removing any weeds. Scatter the seeds and lightly cover them with soil. Keep the soil consistently moist until the seedlings emerge. Thin the seedlings to 8-12 inches apart once they're a few inches tall. Direct sowing is a great option for a continuous supply of blooms throughout the season.

Calendula prefers moderate watering and can tolerate some drought, which is helpful during our Texas heat. However, consistent moisture is key for healthy growth and abundant blooms.

During the spring and fall, when temperatures are milder, water deeply once or twice a week, providing about an inch of water each time. Use the "finger test" – if the top two inches of soil feel dry, it's time to water. In the heat of summer, you may need to water more frequently, especially if rainfall is scarce.

Water at the base of the plants to avoid wetting the foliage, which can increase the risk of fungal diseases in our variable humidity. Signs of underwatering include wilting leaves and dry, brittle petals. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants can help retain moisture and suppress weeds, which is especially helpful during dry spells.

Deadheading is crucial for keeping your Calendula plants blooming throughout the season. Regularly remove spent flowers to encourage the plant to produce more buds. Simply pinch or cut off the flower heads just below the bloom.

Leave some flowers to mature towards the end of the season if you want the plants to self-seed. Calendula readily self-seeds, so you'll likely have new plants popping up in the spring. As the first frost approaches around early November, you can let the remaining flowers go to seed or collect them for next year.

You can expect your first Calendula harvest about 45 days after planting, typically from late April through mid November in Texas. Harvest the flowers when they are fully open and the petals are at their peak color.

Gently pinch or cut off the flower heads, leaving a short stem. The petals are edible and can be used fresh or dried. Regularly harvesting the flowers will encourage the plant to produce more blooms. As the first frost approaches, harvest any remaining flowers before they are damaged by the cold. You can dry the petals and store them for later use.

Calendula is generally a low-maintenance plant, but it can be susceptible to a few problems in our Texas climate.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves curl, yellow, and die.
• What causes it: 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.

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). Fire ants will protect aphids.

Whiteflies

• What it looks like: Tiny, white, moth-like insects that flutter up when disturbed. Yellowing or silvering of leaves. Sticky honeydew residue.
• What causes it: Sap-sucking insects that thrive in warm weather. Overcrowding and poor air circulation contribute to infestations.
• How to fix/prevent it: Yellow sticky traps can capture adults. Strong water spray dislodges them. Insecticidal soap or neem oil can control infestations. Encourage natural predators like lacewings and parasitic wasps.

Texas Specific Challenges: The combination of hot-to-extreme heat, variable humidity, and unpredictable rainfall in Texas can create conditions that favor both fungal diseases and insect infestations. Monitor your plants regularly, provide adequate spacing and air circulation, and water appropriately to minimize these problems.

Calendula makes a great companion plant in the Texas garden. Plant it near tomatoes and peppers to attract beneficial insects that prey on pests like aphids and whiteflies. Calendula also benefits green beans by attracting pollinators.

Avoid planting Calendula near members of the cabbage family, as they can compete for resources.