Calendula (Calendula officinalis) is a short-lived perennial in warmer climates, but in cooler climate zones it is usually grown as an annual flower in garden beds and containers. Although commonly known as pot marigold, calendula is different from the common marigold (Tagetes spp.). It is, however, part of the Asteraceae family along with daisies and chrysanthemums, and has a daisy-like appearance. It is planted in spring after the last frost and grows relatively quickly, flowering six to eight weeks from seeding.
The common name of pot marigold originated from the gold flowers that bloomed during the festivals of the Virgin Mary in Renaissance times (mary + gold = marigold). Ancient Greek, Roman, Arabic, and Indian cultures used calendula as a medicinal herb and as a dye for fabrics, food, and cosmetics. Today, gardeners grow these plants for their cheery flowers and profuse blooming habit. Though they most commonly are seen in varieties with yellow, orange, and red flowers, you can also find them in subtle shades of pink and cream.
|Common Name||Calendula, pot marigold, common marigold|
|Botanical Name||Calendula officinalis|
|Plant Type||Perennial, annual|
|Mature Size||1-2 ft. tall, 1-2 ft. wide|
|Sun Exposure||Full, partial|
|Bloom Time||Spring, summer, fall|
|Flower Color||Yellow, orange, red, white, pink|
|Hardiness Zones||2a-11b (USDA)|
Calendula is primarily an annual unless you live in hardiness zones 9 to 11, where it can be grown as a perennial.
It is easy to grow from seeds directly sown in the garden or containers. Plant seeds indoors in early spring and repot or transplant sturdy seedlings after the danger of frost has passed. Calendula will tolerate poor conditions but grows best when it has rich soil. Once established, it doesn't need much water or fertilizer to grow. Calendula is a full sun plant, however, it's not a fan of sweltering hot temperatures and might start wilting in intense heat.
Pinching back young plants will promote more compact, bushy growth and prevent the plants from becoming leggy. Deadhead the old flowers to encourage reblooming.
Calendula generally prefers full sun, but it sometimes languishes during the hottest months unless it receives some afternoon shade.
Like most members of the daisy family, calendula needs a well-drained soil high in organic material. Dense, wet soils can cause the roots to rot. This plant tolerates a wide range of soil pH but prefers a slightly acidic to neutral soil (6.0 to 7.0).
Water frequently until the plants are established. Mature plants thrive on only occasional watering. Avoid too much water with these plants.
Temperature and Humidity
Calendula prefers mild summer temperatures and may die away by the end of summer in very hot climates.
A hard freeze will kill the plants. If you expect some frost for a day or so, you can protect the plants with a frost blanket overnight and uncover as the sun warms up the air the next day. Three to four inches of mulch will also protect the plants from cold temperatures.
Calendula does not need much in the way of feeding. If planted in fertile garden soil, it requires no additional feeding at all. Marginal soils may require feeding with a balanced, water-soluble fertilizer, but over-feeding can make the plants leggy and spindly.
Container plants require monthly feeding with a diluted, balanced fertilizer.
There are numerous cultivars of Calendula officinalis. Popular varieties include:
- 'Pink Surprise': Ruffled gold and yellow flowers, sometimes with pink edges and dark apricot centers
- 'Touch of Red': Flowers with a mixture of orange and red shades with red-tipped petals
- 'Greenheart Orange': Flowers with orange petals surrounding lime-green centers; a very unusual looking plant
- 'Citrus Cocktail': A compact, short plant with yellow and orange flowers; works well in containers
- 'Dwarf Gem': A compact variety with double-petal blooms of orange, yellow, and apricot; another good variety for containers
- 'Prince': A tall variety that is heat-tolerant with orange and yellow blooms.
- 'Golden Princess': Bright yellow blooms with a contrasting black center.
Although some people find the peppery taste somewhat bitter, the flowers and leaves of calendula can be used as edible flowers in salads and other recipes, either fresh or dried. The petals can also be used to create a rich yellow dye.
Collect calendula flowers in the late morning, after the dew has dried. Pick flowers when they are fully open. To dry the flowers, spread out the cut flower heads on a screen in a dry, shady spot. Turn them occasionally until they are papery dry, then store them in canning jars until ready to use.
How to Grow Calendula From Seed
Calendula is very easy to grow from seeds, which easily germinate and sprout. Seeds collected from the flowers can be saved and replanted; the plants will also readily self-seed in the garden.
Start calendula seeds indoors in a seed starter mix about six to eight weeks before the last frost date. Or, you can sow them directly into the garden just before the last spring frost date. Most plants bloom within two months of seeding. These plants very often self-seed in the garden; don't mistake the seedlings for weeds.
Potting and Repotting Calendula
Although the "pot" in the common name "pot marigold" refers to this plant's traditional use in cooking, calendula is also commonly planted in pots, where it thrives. Most varieties grow well in containers, particularly shorter cultivars.
Use any well-draining, organic potting soil, or make a mixture with a blend of half garden soil and half compost. Make sure the pot has plenty of drainage holes since this plant does not like to be soggy. Potted specimens need regular feeding with a balanced fertilizer.
Common Pests & Diseases
Calendula has no serious insect or disease problems. The plant can sometimes be susceptible to powdery mildew, which can be remedied by good air circulation.
Slugs and snails may feed on the plants, especially when they are young. Keep the ground clear of debris to minimize slug and snail damage. Aphids and whiteflies can sometimes be a problem. To control them, spray them with water or treat them with insecticidal soap.
Is calendula toxic to dogs?
Calendula is not toxic to dogs and cats.
Is calendula a good companion plant?
Calendula is an excellent companion plant for a vegetable garden because it attracts pollinators such as bees and bumblebees, as well as beneficial insects. The bright blooms are a favorite of butterflies.
When should I collect Calendula seeds?
In the late summer or early fall, instead of deadheading your calendulas, leave the faded flowers on the plant until the petals have shriveled and fallen off and the remaining flower heads with the seeds have become dry and turned tan in color. These are the seeds you want to collect for starting the calendula from seed in the following spring.