Whoever hears the word "leek" first thinks of the tasty and healthy vegetable, which is served especially in the winter months and enriches many dishes. Closely related to this are the various types of ornamental onions, which can be found in many flower borders because of their large, usually bright purple flower balls. In the following article you will find out how to plant and care for them and cleverly combine them with other plants.

Ornamental onions are a beautiful addition to the garden

Table of Contents

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  1. origin and distribution
  2. use
  3. appearance and growth
  4. leaves
  5. flowering and flowering time
  6. fruit
  7. Are ornamental onions poisonous?
  8. Which location is suitable?
  9. floor
  10. Plant ornamental onions correctly
  11. What is the best planting time?
  12. The right planting distance
  13. sowing
  14. Prefer
  15. pour ornamental onions
  16. Fertilize ornamental onions properly
  17. Cut ornamental onions correctly
  18. Propagating ornamental onions
  19. hardy
  20. pests
  21. Ornamental onion does not bloom, what to do?
  22. species and varieties

    23. origin and distribution

    Allium plants are at home all over the world, with the vast majority of species being found in the northern hemisphere. Only a few species are native to Germany, including wild garlic (Allium ursinum), which grows wild in mixed and beech forests. Ornamental onion, on the other hand, originally comes from Central Asia, where its wild forms grow in the wide steppes as well as in the mountains. The first plants came to Europe with the Crusaders and soon found their way into the gardens of the monasteries, and later also into the cottage gardens. Most of the around 35 commercially available species are specially bred hybrids. However, species such as the Iranian leek (Allium aflatunense) and the star ball leek (Allium christophii) are also very popular.

    use

    Incidentally, the ornamental onion species also include onions (Allium cepa), which are mostly cultivated purely as useful plants, as well as garlic (Allium sativum), leeks (Allium ampeloprasum or porrum) and chives (Allium schoenoprasum). They all belong to the large Allium family, which includes around 950 different species. In contrast to useful plants, ornamental onions are only used as a pure border plant because of their eye-catching flowers, even if they are also edible.

    appearance and growth

    Ornamental onions are so-called onion flowers, which, depending on the type and variety, can grow up to 150 centimeters. However, some species such as the blue tongue leek (Allium nevskianum) remain significantly smaller with an average height of 12 to 15 centimeters. The most impressive height is reached by the popular giant leek (Allium giganteum).

    Like all onion flowers, the ornamental onion also sprout from the bulbs in spring. However, the above-ground parts of the plant - the leaves and the flower stalks - die off after flowering and after the seeds have ripened, while the bulb hibernates underground as a storage organ and sprout again the following spring. The growing season usually lasts about three to four months.

    leaves

    A long, leafless flower stem and long, narrow and mostly sessile leaves usually sprout from the bulb. The flower stem is also surrounded by a bract that is intended to protect the stem during budding. However, it dries up quickly the bigger and stronger the shaft gets.

    flowering and flowering time

    Most types of ornamental onions flower between May and June, although later-flowering varieties are also commercially available. The large flower umbels typically have a spherical shape, in which many small individual flowers are combined into showy inflorescences with a diameter of up to 25 centimetres. The vast majority of ornamental onion varieties flower in violet tones, but some varieties stand out with flowers in white, pink, red, yellow or even blue.

    Furthermore, ornamental onion flowers are used in fresh bouquets as well as in dried bouquets, which can be kept for many months.

    fruit

    Due to the high nectar content, ornamental onions are popular forage crops for bees, bumblebees, butterflies and other insects. These fertilize the flowers, whereupon capsule fruits form. These contain tiny spherical black seeds.

    Are ornamental onions poisonous?

    Although the ornamental onion is only planted as an ornamental plant in the flower garden, just like its relatives, it is non-toxic and can even be used in a variety of ways in the kitchen. Both the onions and the leaves and even the flowers can be used in salads, stews or for seasoning, although the taste of this plant is of course not as intense and tasty as that of onions and conventional leeks - after all, the breeders are more focused on it the beauty of the flowers and less on the aroma. Incidentally, the delicate flowers look very pretty as an edible decoration on salads and other dishes.

    Only dogs are not allowed to eat leeks - just like other allium species - because they are poisonous for the four-legged friends in higher doses. The ingredients of the plant, which are found in concentrated form mainly in the onions, can break down the red blood cells of the four-legged friends. Incidentally, many other animals, including rodents such as rabbits and guinea pigs, instinctively avoid bulbous plants.
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    Which location is suitable?

    Almost all ornamental onion species need a dry location in full sun. After all, the wild forms come from the dry steppe and stony mountain regions of Asia, where they often thrive in very exposed and barren places.
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    floor

    Allium species often thrive in garden locations where other flowers struggle. The soil should be well drained, dry, humic and as loose as possible. The ornamental onion does not tolerate wet or excessive moisture, here it rots quickly and dies. Plant the bulbs in locations where tulips also thrive. Heavy, loamy substrates, on the other hand, are not suitable.

    Plant ornamental onions correctly

    Plant the allium bulbs in a suitable location, having previously loosened and, if necessary, improved the soil. Loamy soil, for example, can be upgraded with coarse sand and compost so that rainwater drains off better. The planting hole is about three times as deep as the bulb is high. Be sure to plant the end with the root ends down. Mark the planting spots with a stick or something similar so as not to damage the bulbs during any soil work.
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    What is the best planting time?

    Early planting of the bulbs between September and November is ideal, whereby they should take root before the first frost if possible. The only exceptions are ornamental onion varieties that sprout early, such as 'Purple Sensation', for which an earlier planting date would also result in very early sprout - with the risk that it will freeze to death due to (late) frosts.
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    The right planting distance

    The planting distance varies between the types and varieties of ornamental onions, and essentially depends on the respective growth height and width. The 'Globemaster' variety, for example, which grows around one meter high, should be planted in the bed at intervals of around 20 centimetres. You can plan groups of 24 to 26 plants per square meter. The giant ornamental onion even needs up to 40 centimeters of space per plant (10 to a maximum of 20 plants per square meter), while the bluetongue leek, although short but quite wide, also requires a distance of 20 to 25 centimeters.

    sowing

    Ornamental onions can also be propagated very well using seeds, which you can obtain from the ripe seed pods or buy in stores. The ideal time for sowing is March to April, because the cold germinator needs a phase with temperatures below ten degrees Celsius. The cold stimulus breaks the germ inhibition as soon as the temperatures subsequently rise. Sow the seed directly into the well-prepared bed, mixing in compost with the potting soil. Place two seeds in a planting hole about one centimeter deep and cover them loosely with soil. Prick out later if necessary so that the plants are not too close together.
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    Prefer

    Of course, ornamental onions can also be preferred on the home windowsill, but this project is unnecessary for several reasons. On the one hand, once germinated, the plants grow very quickly and flower just as quickly. On the other hand, it is difficult to germinate the seeds indoors. You would have to

    • store the seeds harvested in autumn in a moist and warm place over the winter
    • ventilate regularly and check for mold
    • store in the vegetable compartment of the refrigerator for eight weeks from December / January
    • and do not sow in seed pots until March

    It becomes easier if you sow the seeds directly in the bed immediately after the summer harvest, where they can then germinate and grow next spring. You don't even need to harvest the seed yourself: ornamental onions tend to self-sow provided the location and growth conditions are right.

    pour ornamental onions

    Ornamental onions do not need any additional watering, since the plants, which originate from arid regions, do not tolerate excessive moisture. But even if the plants only need a little water, they must not dry out.

    Fertilize ornamental onions properly

    Fertilizers are essential for beautiful flowering instead. Humus or compost is very suitable, which is put directly into the planting hole when planting. In the spring there is further fertilization with compost or self-made plant manure, with a mixture of nettle and comfrey manure being particularly suitable.

    Cut ornamental onions correctly

    Never cut dried and faded ornamental onions too early, as the nutrients still contained in the above-ground parts of the plant are absorbed by the onion and needed for the budding in the coming year. Therefore, only cut off the leaves when they are completely dry. You can leave the inflorescences even longer, as they still look attractive when they have faded. Whether you leave the seed heads or remove them is your decision: if you don't want to sow the ornamental onions, it makes sense to cut them off.
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    Propagating ornamental onions

    Ornamental onions are very easy to propagate yourself. You can use the seeds for this - or the daughter bulbs that each bulb develops. These offshoots, also known as brood bulbs, develop directly on the mother bulb and can easily be detached from it in autumn and planted separately. To do this, cut off the above-ground parts of the plant close to the ground and dig out the spring onions carefully and without damaging them. Spring onions are suitable for propagation when they are thick, plump and white.
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    hardy

    Not all ornamental onion species are hardy, which is why overwintering takes place differently. Only cut down frost-hardy varieties in autumn and cover the planting site with brushwood, while non-hardy onions must be dug up and overwintered in a cool and dark place. The few species that are sensitive to frost are often easier to cultivate in a pot that you simply put in a cool cellar in autumn and empty out again in spring.
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    pests

    Like all Allium species, ornamental onions are often attacked by the onion fly (Merodon equestris). In addition to this, there are two other fly species, Eumerus tuberculatus and Eumerus strigatus, which, like the onion fly, lay their eggs on the bulb. After the maggots hatch, the onion serves as food for them, is eaten away and eventually rots. Prevent the spread by never throwing rotten spring onions in the compost. If an infestation has already occurred at one location, never plant new bulbs in the same place.

    Since the flies do not like carrots, they can be kept away by regularly watering them with carrot herb decoction. The principle is already known from the kitchen garden, where onions should always be cultivated together with carrots.

    Furthermore, the vine weevil likes to taste the onions, while aphids and snails tend to feast on the above-ground parts of the plant.

    Ornamental onion does not bloom, what to do?

    The large ornamental onion species in particular tend to flower lazily after just a few years. This is often due to a lack of nutrients, which can be remedied by regular fertilization. But if that doesn't help either, there are other causes. Drought in spring, pest infestation, wetness and the associated rotting onions are possible reasons for the lack of flowering.

    Sometimes a change of location helps, where you dig up the bulbs in the fall and plant them in a new, possibly more suitable spot in the garden. Mix the excavation well with compost and horn shavings (€32.93) to stimulate renewed growth in the coming spring.

    tips

    If you regularly provide the ornamental onion with crushed egg shells, it will bloom all the more beautifully.

    species and varieties

    There are around 900 different types of ornamental onions with numerous varieties worldwide. We have put together the most beautiful ones for your home garden for you here.

    • Purple Globe Allium 'Purple Sensation' (Allium aflatunense): up to 90 centimeters high, flower balls up to ten centimeters in diameter
    • Gold Allium 'Jeannine' (Allium moly): bright golden yellow, flat inflorescences, up to 35 centimeters high, for shady locations
    • Garnet Globe Allium (Allium atropurpureum): wine-red flowers, height of growth up to 80 centimeters
    • Blue allium (Allium caeruleum): very early flowering period from March, gentian blue flower colour
    • Star ball leek (Allium christophii): growth height up to 40 centimeters, amethyst-colored flowers up to 25 centimeters in size
    • Bluetongue Allium 'Ivory Queen' Allium (karataviens). Growth height up to 25 centimetres, white flower balls up to 15 centimeters in size
    • Giant leek 'Ambassador' (Allium giganteum): growth height up to 200 centimetres, purple-violet flower balls
    • Giant leek 'Globemaster' (Allium giganteum): growth height up to 200 centimetres, purple-violet flower balls
    • Giant white leek 'Mount Everest' (Allium giganteum): growth height up to 120 centimetres, green-white flower balls
    • Dwarf ornamental onion (Allium oreophilum): growth height up to 15 centimetres, carpet-like habit, crimson flowers
    • Rose leek (Allium ostrowskianum): growth height up to 25 centimetres, large, crimson flower balls
    • Lilac onion (Allium pulchellum): late flowering period between July and August, height of growth up to 40 centimetres, numerous lilac-colored flowers
    • Wild garlic (Allium ursinum): also wild garlic, for shady locations, height of growth up to 30 centimetres, white flowers

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Indoor plants