Pot Marigold

The pot marigold (Calendula officinalis) is part of the daisy family (Asteraceae) and probably originally came from the Mediterranean. It’s one of the oldest decorative plants grown in gardens, so it is almost impossible to now establish where it originally came from.

Pot marigolds are upright, bushy annual herbaceous summer flowers. Depending on the variety and location, they grow to up to 7.87 - 24 inches in height and have angular, brachiate stems.

The sessile, alternate leaves of the pot marigold are light to medium green, and covered in hair. Their shape varies, ranging from ovate to lanceolate. The length of the lamina varies between 1.57 inches and 5.51 inches. When rubbed, they give off a very characteristic smell.

Pot marigolds bloom from June to October. The plants flower intensively over the first six weeks, forming new buds in fall that produce slightly smaller flowers. The terminal composite flowers close at night, and range from creamy yellow to scarlet red as well as from single to double. Some varieties also have a dark flower head.

Like almost all daisies, pot marigolds form achene fruits. This a special, single-seeded form of indehiscent fruit. They are curved to varying degrees and some are almost ring-shaped.

Pot marigolds flower most intensively in full sun. The soil should be slightly loamy and not too moist. Lots of nitrogen leads to excessive growth, less intense flowering and a lack of resilience.

Pot marigolds germinate very quickly and reliably, so can be sown direct in the bed from April to June. The soil should be loosened in advance and weeded, then the seeds can be either be raked in or covered with a thin layer of compost, around 0.39 inches high. After germination, the seedlings should be thinned out to a distance of 9.84 to 12 inches. If the excess plants are carefully removed from the soil with a small trowel or spade, you can replant them in another location.

If you want your pot marigolds to flower in May or June, you should start them in a greenhouse or on a bright windowsill. Sow the seeds from mid March into regular potting soil. Sprinkle sand thinly over the soil and keep it consistently moist. Germination takes a good ten days at temperatures around 60 degrees Fahrenheit. Three weeks after germination, you can pot the young plants on into individual pots, then plant out in the garden from mid May in a location that is ideally bright and cool, at around 50 degrees Fahrenheit. It’s advisable to not keep the plants too moist as they will produce more flower buds. After the final frost, pot marigolds can be planted into beds around 9.84 to 12 inches apart. Tip: if you sow sets of pot marigolds at intervals from March to June, you can enjoy their full floral glory the whole season long.

In mild zones without regular late frost, pot marigolds generally sow their own seed: they self-seed generously in fall, and new seedlings will simply appear in spring.

Pot marigolds require minimal care. Around two liters of mature compost when preparing the bed will suffice in terms of nutrients for a whole year. Pot marigolds are only watered sparingly to encourage flowering. If you don’t mind the work, you can regularly remove dead heads to encourage the formation of new flowering stems - the last blooms of late summer should be left if you would like these summer flowers to self seed.

Pot marigolds are classic cottage garden plants and are planted as companion plants for vegetables. Just like true marigolds, their roots give off toxins that discourage nematodes in the soil. They are also very suitable groundcover plants and can be used in mixed summer flower beds or to fill gaps in shrubberies. Pot marigolds are also used as green manure. For example, they can be sown on a former strawberry bed to combat soil fatigue.

There is a wide range of varieties that may be widespread only within a local area, as they are often inherited from generation to generation within families. The most beautiful pot marigold varieties available to buy include “Orange Gitana” with its orange flowers and “Yellow Gitana” with corn yellow petals and a dark center. Both remain very compact, growing no higher than 12 inches. “Orange Stachelschwein” is a nicely dense orange variety with a long flowering period and rolled, pin-like petals. “Neon” features large, densely packed orange blooms. The tips of the petals are wine red. At 24 inches tall, they also make good cut flowers.

As well as seeds for specific varieties, there are plenty of seed mixes with a range of yellow and orange varieties. One of the best known is the “Daisy” blend, complete with four compact varieties in lemon yellow, golden yellow, apricot and deep orange.

As pot marigolds can only be propagated through sowing seeds, you can simply collect seeds from your own plants in summer. Let them dry thoroughly and store them in jars or paper bags in a cool, dark place until it’s time to sow in spring. Alternatively, you can sow all your gathered seeds in September and then cover the bed with fir twigs. Winter frost won’t do much to these seeds, but they do germinate early so are at risk from late frosts.

Fungal diseases appear on pot marigolds relatively often, especially downy and powdery mildew. Leaf spot diseases may also pose an occasional problem. A well ventilated location, quite moist, permeable soil and sufficient distance between plants are the best prevention. When it comes to animal pests, aphids, shield bugs and leaf-miner flies are the most significant. Pot marigolds are also a favorite food of snails.