Calendula in Zone 6A — Pacific Northwest

Calendula is a fantastic addition to any Pacific Northwest garden. The cheerful orange and yellow blooms brighten up overcast spring days, and the petals have a slightly peppery taste that’s great in salads. Plus, Calendula is known for its medicinal properties, making it a versatile and satisfying plant to grow in our region.

While we enjoy mild summers, our 148-day growing season means we need to be smart about timing. Cool soil in spring and the occasional bout of late blight can present challenges, but with the right planning, you can enjoy a bountiful harvest of Calendula blooms.

Starting Calendula indoors is possible, but not always necessary given our mild summers. If you want a head start, begin in early to late March, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix, provide warmth (a heat mat is helpful), and ensure adequate light, especially given our overcast spring days.

Bottom watering is a great way to keep the soil consistently moist without overwatering; just set the tray in a shallow dish of water and let the soil soak it up. Starting indoors buys you some time, especially if we have a particularly cool spring.

Transplant your Calendula seedlings outdoors in late April through early June, once the danger of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Space them 8-12 inches apart to allow for good air circulation, which helps prevent powdery mildew. Keep an eye on the weather forecast—a late cold snap can still happen—and protect your young plants if needed.

Direct sowing Calendula is a straightforward way to grow these cheerful flowers in the Pacific Northwest. Sow seeds directly into the garden in late April through early August. Choose a spot with full sun to part shade and prepare the soil by loosening it and removing any weeds.

Calendula seeds germinate best in soil that is at least 60°F, so wait until the soil has warmed up a bit. Sow the seeds about ¼ inch deep and space them 8-12 inches apart. Keep the soil consistently moist until the seedlings emerge, which usually takes about a week.

Calendula prefers moderate watering, which is good news in the Pacific Northwest where we get plenty of rain. During our wet springs, you likely won't need to water much at all. Once the dry summer months arrive, check the soil moisture regularly.

Stick your finger about 2 inches deep into the soil; if it feels dry, it's time to water. Aim for about 1 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 powdery mildew in our dry-summer humidity.

Signs of underwatering include wilting leaves and stunted growth, while overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants helps retain moisture and keeps the soil cool, which Calendula appreciates.

Deadheading is key to keeping your Calendula plants blooming throughout the season. Regularly remove spent flowers, snipping them off just below the flower head. This encourages the plant to produce more blooms rather than putting energy into seed production.

Continue deadheading throughout the summer and into the fall. If you want to save seeds, allow a few flowers to mature and dry on the plant. As the first frost approaches in early October, you can collect any remaining flowers and seeds.

You can expect your first Calendula harvest in early June through mid October, about 45 days after planting. Harvest the flowers when they are fully open, ideally in the morning after the dew has dried. Look for blooms with vibrant, fully developed petals.

To harvest, simply snip the flower head off the plant with scissors or pruners. Be gentle to avoid damaging the surrounding foliage. Regular harvesting encourages continuous blooming, so the more you harvest, the more flowers you'll get.

As the first frost approaches in early October, harvest any remaining flowers, even if they aren't fully open. You can dry them indoors for later use.

Here are some common problems you might encounter with Calendula in the Pacific Northwest:

Powdery Mildew

• What it looks like: A white or grayish powdery coating on leaves and stems. Leaves may curl, yellow, and eventually die.
• What causes it: Fungi that thrive in warm days, cool nights, and moderate humidity. Surprisingly, dry leaf surfaces favor it. Our dry summers with cool nights can create ideal conditions.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays can help. A milk spray (1 part milk to 9 parts water) is also effective.

Aphids

• What it looks like: Clusters of tiny green, black, or white soft-bodied insects on stems and leaf undersides. You might also see sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Populations can explode in warm weather. Ants may farm them for honeydew.
• How to fix/prevent it: Knock them off with a strong water spray. Encourage ladybugs and lacewings (natural predators). Insecticidal soap works well for heavy infestations. Neem oil is also effective.

Whiteflies

• What it looks like: Tiny white insects that fly up when you disturb the plant. Yellowing or stippled leaves. Sticky honeydew residue.
• What causes it: Sap-sucking insects that thrive in warm, sheltered conditions. They can quickly multiply and weaken plants.
• How to fix/prevent it: Hang yellow sticky traps to catch adult whiteflies. Spray plants with insecticidal soap or neem oil, paying attention to the undersides of leaves. Ensure good air circulation around plants.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer humidity can create conditions favorable for powdery mildew, so good air circulation is key. Slugs can also be a problem, especially for young plants, so use appropriate control measures.

Calendula makes a great companion plant in the Pacific Northwest garden. Plant it near tomatoes and peppers; Calendula attracts beneficial insects that help pollinate these vegetables. Plus, Calendula can deter some pests that bother tomatoes.

Calendula is also a good companion for green beans. It can attract pollinators and help protect the beans from certain pests. There aren't any specific plants to avoid planting near Calendula.