Ornamental onion (Allium) shines in many different colors. The broad palette ranges from simple white to delicate pink and strong red to deep blue and purple, which often has a metallic sheen. In the meantime, however, newer varieties are also available that shine in yellow and pink and have differently shaped flower balls. Typical of the ornamental onion is the dewy leek or onion odor that occurs when the plant is touched or damaged and is due to the different essential oils.
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Relatives and origins
The close relatives of garlic, onions and chives fit harmoniously into every bed and become a real eye-catcher in the garden. The large genus Allium (leek) is not only convincing in culinary terms, but also with its extremely decorative types and types of ornamental leek. There are more than 800 different species of the remarkable plant worldwide, many of which have found a home in Central European gardens due to their unique blooms. But the ornamental onion is primarily native to Central Asia, Turkey and Iran, especially in steppes and slopes. The plant is also located in Israel, North America on the territory of the former Soviet Union and in China.
The biodiversity of the allium
The constantly growing range of ornamental onions ranges from larger types and true giants to curiosities to small and low representatives. Especially with the large-flowered varieties such as the star ball leek or the giant leek Globemaster, wonderful bed designs can be realized.
- Giant Leek (Allium giganteum) – very impressive with a flower stem height of up to 150 cm and compact purple flower balls that have a stately 12 cm in diameter
- Allium jesdianum Akbulat – is a kind of ornamental onion that is mainly native to Uzbekistan and develops 10 wonderful flower umbrellas from May to June, which can also be kept in the vase for a long time
- Allium ‘Gladiator’ – has a stable 80 cm – 100 cm high stem on which 25 cm large flower umbels in beautiful purple form
- Allium christophii – the star ball leek is an absolute eye-catcher, with a stately size between 60 cm to 80 cm and a 20 cm large flower, it is characterized by its metallic sheen and offers a long flowering time
- Allium Mount Everes – is a white giant leek with dreamlike white flower balls, which can reach a height of up to 1 m and shows its full bloom in May
- Allium carinatum ssp. pulchellum – the lilac-leek is adorned with 10 cm large violet-pink flowers, the plant height is 60 cm, prefers a well-drained location, blooms from July
- Allium Early Emperor – is a very early blooming giant onion with violet flower balls, which feels most comfortable in normal garden soil in a partially shaded place and brings it to a height of 80 cm
- Purple Sensation – was first presented at the famous Chelsea Flower Show in England and is characterized by a height of 90 cm and red-violet inflorescences that reach a diameter of up to 10 cm
- Allium Firmament – combines star-shaped, shiny single flowers into a dreamlike purple flower ball, which adorns the garden in June with 60 cm – 80 cm
- Allium schubertii – also known as Schubert’s ornamental onion with 30 cm large pink and purple single flowers that open on flower stalks of different lengths, not hardy therefore mainly suitable for pots, impresses as a cut flower in the vase with only one flower
- Allium hirtifolium var. Album – the fragrant drumstick leek thrives wonderfully in a dry location between May and June and reaches a considerable height of 90 cm to 1.20 m
One of the particularly interesting types of ornamental leek
- the Bulgarian leek, which likes it particularly sunny and forms large dark red, brown or pale yellow umbels from long, pointed flower buds that open from May to June.
- and the Nectaroscordon siculum, which is also known as Sicilian honey leek and with its decorative, multicolored buds, is a great ornamental plant in borders but is also often planted in perennial beds.
The easy-care, very adaptable and robust ornamental onion prefers a nutrient-rich, calcareous, permeable and loose soil. In addition, the perennial bulb plant thrives best in full sunlight, because the sunnier the location, the better it will grow and bloom. The only exception is wild garlic, which prefers a partially shaded place. Ornamental onion also likes to find a place between different perennials.
While the main flowering time of the undemanding ornamental onion is between May and June, there are also species that bloom from April to September. The attractive ornamental onion only takes up a small space of its own and sprouts quite early. But after flowering, the plant retreats almost completely, which means that it does not require much care.
Fertilizing and watering
If the allium is to bloom splendidly every year, it is necessary to fertilize the bulb at regular intervals. The following applies: the bigger the flower ball, the more fertilization!
- The Allium bulbs are fertilized when the leaves appear, i.e. in the drive
- with organic fertilizer, horn shavings, compost and, if you like, a little soil activator
- to do this, the fertilizer is simply sprinkled around the plant and hooked in
- if the weather is very dry, water it abundantly at least once
- If the ornamental onion grows on an average garden soil, fertilizer should not be used
- because too much nitrogen can lead to fewer flowers and increased foliage
- or the flower stalks begin to “shoot” upwards
- and especially tall varieties tend to snap off
The natural habitat of Allium is characterized by little rainfall, which is why the ornamental onion gets by with only little moisture in our native regions. But even the short vegetation phase only requires moderate watering.
After seed ripening and insect pollination have started, most species wilt quite quickly and begin to store all the important nutrients in the bulbs. Because often the entire vegetation period does not last longer than 3 to 4 months. However, this also means that numerous types of ornamental onion react extremely sensitively to impermeable, moist garden soil, similar to tulips. The onions begin to rot quickly under permanently moist conditions.
Ornamental onion does not require a lot of care, which is why this is limited in particular to the removal of leftover leaves and cutting off the withered inflorescences when the plant feeds in in midsummer. Alternatively, the seed stocks can also be left standing. However, for varieties that tend to multiply excessively, it is advisable to prune them before the seeds are ripe. But this should never be done too early, otherwise the plant will lose its strength for the next flowering period. When the foliage is completely yellowed, you can either cut back or pluck it. However, since it turns yellow and becomes unsightly very quickly, it is ideal to plant ground cover such as cork’s bill, lady’s mantle, lavender, catnip or sage around the ornamental onion.
Propagation by means of bulbs and seeds
For the propagation of ornamental onions, there are two methods to choose from: the seeds and the bulbs.
bulb properties Like all flower bulbs, the onion of the ornamental onion already contains all the individual components with the petals and the stem, but also parts of the flower such as the stigma, which is necessary for the later reproduction of the plant. However, the onions of the individual Allium species differ considerably in their structure. In addition, reserve substances are already stored in the onion of the ornamental leek, which enable the plant to spend time without water.
Generative propagation through seeds
- the inflorescences are not removed immediately after flowering
- but only after the seeds have turned black
- they can be sown immediately after harvest or after a short storage in a dark, dry place
- special potting soil is particularly suitable, into which a little quartz sand is worked to keep this substrate evenly moist
- Avoid waterlogging!
Propagation by means of brood
onions … if the buds in the onions are used, it is referred to as vegetative propagation that does not require much help, since ornamental onions form brood onions completely independently. These can be taken out of the ground after a few years and replanted at a different location. A few species also form new bulbs in the inflorescence above the ground, which can also be transplanted
Allium bulbs are planted in humus-rich soil in autumn from September to November. Ornamental onions can also be brought into the frost-free soil in spring.
- at a depth of around 25 cm
- larger bulbs should be planted three times as deep as the height of the bulb
- Check for mold before planting and sort out
- Plant in well-drained soil
- in loamy soils, a shovel of coarse-grained construction sand ensures that rainwater seeps away
- In order for the onion to get through the harsh winter months, you can also put a 5 cm deep layer of sand in the planting hole
- fill with a layer of compost and horn shavings or chicken or cattle manure pellets or with a mixture of soluble fertilizer and water
- Give about 3 cm of water a week in spring
- Regularly rid of weeds so that a supply of nutrients is guaranteed
- young plants appear in spring only after exposure to low temperatures, as ornamental onion is a cold germ
The most common onion species are hardy and can safely overwinter in the ground during the cold season. Since Allium does not tolerate much moisture during this period, the onions in buckets should always be covered with brushwood.
Ornamental onion is often visited by numerous nectar-seeking insects and is very rarely eaten by voles. Ornamental onion is usually avoided by pests because of the onion smell, but it can also be attacked by aphids. The pests that appear in spring can then be successfully combated with chemical insecticides or tried and tested home remedies.
Ornamental onion forms a wonderful ensemble in beds and borders as a group with several plants. But it can also be used as a cut plant in the vase to enchant the stylish living ambience or form a very special highlight in the tub or plant pot on the balcony or terrace. While smaller species also come into their own in rock gardens, larger varieties only really unfold their full bloom in the cottage garden. After flowering, ornamental onions are ideal as a drying bouquet in the vase.