Calendula in Zone 5B — Mid-Atlantic

Calendula is a fantastic addition to any Mid-Atlantic garden. The bright, cheerful flowers are edible, medicinal, and attract beneficial insects to help with our region's pest pressures. Plus, it thrives in our four seasons, offering a vibrant splash of color from late spring right through fall.

Our humid summers and occasional variable spring weather can present challenges, but with a little planning, you can easily grow Calendula successfully. Our 178-day growing season gives you plenty of time to enjoy these beauties.

Starting Calendula indoors in the Mid-Atlantic is possible, but generally not necessary. Because it's so easy to direct sow, starting indoors is really only useful if you want an extra-early bloom.

If you're keen to get a head start, sow seeds indoors from mid-February through early March, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix, provide warmth (a heat mat helps), and ensure adequate light, especially since our spring weather can be overcast. Bottom watering is great for seedlings; just set the tray in a shallow dish of water until the soil surface is moist.

Transplant your Calendula seedlings outdoors from early April through mid-May, after the danger of hard frost has passed. Be sure to harden them off first by gradually exposing them to outdoor conditions for about a week.

Space plants 8-12 inches apart to allow for good air circulation, which is crucial in our humid Mid-Atlantic climate. Keep an eye on the forecast for any late frosts, which can happen even in April.

Direct sowing Calendula is the easiest way to grow them in the Mid-Atlantic. You can sow directly into the garden from early April through mid-August. This gives you a long window for successive sowings and continuous blooms.

Prepare the soil by loosening it and removing any weeds. Calendula isn't too picky about soil, but well-drained soil is always best, especially with our even rainfall. Simply sow the seeds about ¼ inch deep and keep the soil moist until they germinate. Space plants 8-12 inches apart.

Calendula prefers moderate watering, which is especially important to understand in our humid Mid-Atlantic summers. While it can tolerate some drought, consistent moisture encourages the best blooms, especially during the cooler parts of our four seasons.

During the spring and fall, when temperatures are milder and rainfall is more frequent, you may only need to water once or twice a week. In the heat of summer, especially when we're not getting regular rainfall, check the soil moisture more frequently. Stick your finger about two inches deep into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week, either from rainfall or irrigation.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate. Overwatering can lead to root rot, so watch for yellowing leaves. Underwatering will cause the plants to wilt and the blooms to fade. A layer of mulch around the base of the plants helps retain moisture and suppress weeds, which is especially helpful with our even rainfall.

Deadheading is key to keeping your Calendula blooming throughout the season in the Mid-Atlantic. Regularly remove spent flowers to encourage the plant to produce more blooms instead of setting seed.

Simply pinch or cut off the flower heads just below the base of the flower. You can do this throughout the growing season, from late May through late October. Towards the end of the season, around our average first frost in mid-October, you can let some of the flowers mature and set seed if you want them to self-sow or if you want to collect seeds for next year.

You can expect your first Calendula harvest in the Mid-Atlantic from late May through late October, depending on when you sowed the seeds. The flowers are ready to harvest when they are fully open and the petals are vibrant.

To harvest, simply cut the flower heads off the stem with scissors or pruners. Harvest in the morning after the dew has dried for the best flavor and medicinal properties. Regular harvesting encourages more blooms, so keep at it throughout the season. As the first frost approaches in mid-October, harvest any remaining flowers to dry or use fresh.

Here are some problems to watch for with Calendula in the Mid-Atlantic:

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 our 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 our warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings. Insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer.

Whiteflies

• What it looks like: Tiny, white, moth-like insects that fly up when disturbed. Yellowing leaves, sticky honeydew.
• What causes it: Warm, humid conditions. Overcrowding and stressed plants.
• How to fix/prevent it: Sticky traps to catch adults. Strong water spray. Insecticidal soap or neem oil. Encourage beneficial insects like lacewings and ladybugs.

Mid-Atlantic Specific Challenges: Our humid summers can exacerbate fungal diseases like powdery mildew. Regular monitoring and good air circulation are essential. Also, be vigilant about pests like aphids and whiteflies, which thrive in our warm, humid conditions.

Calendula makes a great companion plant in the Mid-Atlantic garden. Plant it near:

• Tomatoes: Calendula attracts beneficial insects like ladybugs and hoverflies, which prey on aphids that can plague tomato plants.
• Peppers: Similar to tomatoes, peppers benefit from the beneficial insects attracted by Calendula, reducing pest pressure.
• Green Beans: Calendula can help deter bean beetles, a common pest in our region.

There are no specific plants to avoid planting near Calendula.