marigold calendula officinalis
The marigold (Calendula officinalis) belongs to the family of composite flowers (Asteraceae) and probably originates from the Mediterranean region. It is one of the oldest ornamental plants cultivated in gardens, so its original range can hardly be traced today.
Its name suffix ‘officinalis’ comes from the Latin word ‘officina’. It is actually called “office”, but was used in the 18th century by Carl von Linné, the founder of the botanical plant nomenclature, in the sense of “laboratory” or “pharmacy” as a species name for many medicinal plants. The petals of marigolds contain anti-inflammatory substances. They are processed into ointments or used as infusions to treat wounds. Since the dried petals do not lose their colour, they used to be ground to cut the expensive saffron.
Marigolds are erect and bushy growing annual herbaceous summer flowers. Depending on location and variety, they grow to a height of 20 to 60 centimeters and have angular, branched stems.
The undeciduous, alternate leaves of marigolds are light to medium green and hairy. Their shape is very variable and ranges from reverse ovoid to lanceolate. The length of the blade varies between 4 and 14 centimeters. When they are rubbed, they emit a very characteristic smell.
Marigolds bloom from June to October. The plants flower intensively for the first six weeks and then form new buds until autumn, which produce somewhat smaller flowers. The terminal composite flowers are closed at night and, depending on the variety, cream-yellow to carmine and simple to full. Some varieties also show a dark flower basket.
Marigolds, like almost all composite flowers, form so-called achenes as fruits. This is a special, lonesome form of the closing fruit. They are curved to different degrees and some are almost ring-shaped – hence the German name Ringelblume.
Location and soil
In full sunny locations the marigold flowers bloom most intensively. The soil should be slightly loamy and not too damp. If it contains a lot of nitrogen, the plants become very massive, flower less intensively and are not particularly stable.
Sowing and planting
Marigolds germinate very quickly and reliably, so they can be sown directly into the bed from April to June in the desired place. The soil is loosened beforehand, weed is removed and the seeds are then lightly raked in or covered with a thin layer of compost about one centimeter high. After germination, the seedlings are separated at a distance of 25 to 30 centimeters. If you carefully remove the surplus plants from the soil with a small shovel or spoon, they can be replanted elsewhere if necessary. If your marigolds are to flower in May or June, a pre-culture in the greenhouse or on a bright windowsill is necessary. Sow the seeds from the middle of March in commercial growing soil. Then sift a thin layer of sand over the soil and keep it evenly moist. Germination takes a good ten days at temperatures around 15 degrees. Three weeks after germination, you can transplant the young plants into individual pots and then cultivate them as light and cool as possible at around ten degrees until they are planted out in the garden in mid-May. It is advisable not to keep the plants too moist because they will then grow more flower buds. According to the Ice Saints, marigolds are planted in the bed at a distance of 25 to 30 centimeters. Tip: If you sow your marigolds in several sets from March to June, you can enjoy the full flowering splendour throughout the season. In mild regions without regular late frosts, marigolds usually take the sowing into their own hands: in autumn they sow plenty of seeds and in spring the new seedlings appear in the bed.
Marigolds need only a minimum of care. A fertilisation with around two litres of mature compost during bed preparation covers the nutrient supply for the whole year. Ringelblumen are poured only moderately, in order to promote the bloom beginning. If you are not afraid of the effort, you can also regularly cut out the withered inflorescences to promote the formation of new flower stems – but you should leave the last flowers in late summer if you want the summer flowers to sow themselves.
Marigolds are classic farm garden plants and are often planted as mixed cultivation partners for vegetables. Like the related student flowers, their roots secrete toxins that keep nematodes away from the soil. However, they are also very suitable as area planting or for mixed summer flower beds and can be used to close gaps in the perennial bed. Marigolds also have a certain significance as green manure. For example, one likes to sow them on former strawberry beds in order to counteract soil fatigue.
As flowers for colourful summer bouquets, you should cut stems that have just opened their flower buds – they last the longest in the vase. If you hang them upside down in a cool, airy place to dry, you can also use them for drying bouquets. For balcony boxes and other plant containers, marigolds are only suitable to a limited extent, however, because they quickly become unsightly after the main flowering period and hardly set any new flower buds.
There is a multitude of different varieties, some of which are only locally distributed and are often “passed on” from generation to generation within the family. Some of the most beautiful marigold cultivars on the market include ‘Orange Gitana’ with orange flowers and ‘Yellow Gitana’ with corn yellow petals and a dark centre. Both remain very compact with growth heights of up to 30 centimeters. Orange Porcupine’ is a well-stocked orange variety with a long flowering period and rolled up, prickly petals. Neon’ bears large, densely filled orange flowers. The tips of the petals are wine red. With a growth height of 60 centimeters, it is well suited as a cut flower. In addition to the pure varieties, there are also many seed mixtures on the market with different cultivars in yellow and orange. One of the best known is the ‘Daisy’ blend with four compact growing varieties in lemon yellow, golden yellow, apricot and deep orange.
Since marigolds can only be propagated by sowing, you can simply collect seeds from your own plants in summer. Let it dry well and keep it cool and dark in screw jars or paper bags until sowing in spring. Alternatively, you can sow the collected seed in September and cover the seed bed with fir twigs. Winter frost does not make up much of the seeds, but they germinate very early in spring and are then at risk of late frost.
Diseases and pests
Fungal diseases, which occur relatively frequently in marigolds, are downy mildew and downy mildew. Occasionally it comes also to the infestation with leaf-spot-diseases. An airy location, moderately moist, permeable soil and sufficient planting distances are the best preventive measures. Aphids, leaf bugs and leaf miner flies are important in animal pests. In addition, marigolds are often eaten by snails.