The tier or aerial onion is rarely found. However, with its striking appearance, versatile plant parts and easy care, it is an asset to any garden.
The tiered onion (Allium x proliferum or Allium cepa var. viviparum) is beautiful a bit strange to look at: the small onions do not form underground, but above ground on stems, where they sprout directly and thus form several "tiers". The tier onion owes its name to this fact. But the air onion doesn't just have a lot to offer visually. Parts of the plant can also be used in the kitchen almost all year round. In this article you will learn everything about growing bunch onions, from planting to harvesting and use.
Plant onion: origin and properties
The tier onion, also called aerial or Egyptian onion, is a rather unknown representative of the genus Allium. The onion species, which probably originally came from Siberia, is also hardy here and even evergreen in mild winters. Then the round, hollow leaves of aerial onions can be harvested all year round. The plants can grow up to 80 cm high and form small bulbils instead of flowers from June to September. It is not uncommon for these to sprout on the stem and thus form a second, sometimes even a third tier. As summer draws to a close, the stalks break off and the bulbs sink to the ground. There they root and thus ensure the propagation of the mother plant. This is also reflected in one of the Latin names: "Viviparum" roughly means "live-bearing".
Plant onions
Flying Bulb Plants can be purchased at speci alty stores. However, the small spring onions are often passed on from gardener to gardener. Bunch onions cannot be grown from seed, as the plant does not flower and therefore does not produce seed.
Set onions are weak consumers and have very low requirementsthe location. They prefer sunny to half-shady locations on calcareous, humus-rich and loose soil with a pH above 6.5.
Important: Keep a cultivation break of at least 4 years between planting the onion and other leek plants such as onions, leeks and spring onions, otherwise crop rotation diseases can occur.
You can also grow air bulbs in a pot with a volume of 10 liters or more. For this we recommend our Plantura organic tomato & vegetable soil, as it has a loose structure and a high potassium content - both are important for he althy, aromatic bulb plants. In addition, the soil is peat-free and is sustainably produced in Germany. The soil should be thinned out by adding 30% sand, which also ensures better water drainage. The best time to plant tier onions is either in late summer from August.Planting onions step by step:
- Prepare the soil of the bed well by clearing it of weeds and loosening it by hoeing.
- Soils in our regions naturally acidify over time. For example, one factor that enhances this natural process is fertilization. It can therefore be helpful to work some lime into the soil before planting, such as our Plantura Organic Lawn & Garden Lime. If you are unsure whether liming is necessary, you should first determine the pH value of your soil.
- Place the onions 30 - 40 cm apart on the ground and press down lightly. Alternatively, you can plant the bulbs about 5 cm deep in the ground.
- In the following time it is important to ensure that the soil does not dry out. But it should never be too wet around the onion, because then it can happen that the onion begins to rot and does not sprout.
Tip: It is best to plant onions that have not yet sprouted and look he althy. This increases the chances of good growth.
The right care
Set onions are easy to care for. Like all onions, they are weak consumers and usually do not require fertilizer. You should be particularly careful with nitrogen-rich fertilizers: too much nitrogen increases vegetative growth, among other things, so less onion mass is formed. If necessary, however, a fertilizer containing potash can be applied in the spring.Potassium is also an important plant nutrient, which plays an important role in the water balance, for example, and makes the plants more stable, disease-resistant and frost-resistant.
Also, aerial bulbs only need to be watered during longer periods of drought.
Above all at the beginning of growth it may still be necessary to remove weeds from time to time around the growing bulb plants.
Tip: Old and wilted foliage can be removed periodically to make room for new stems. An important pest of the bunch onion is the onion fly (Delia antiqua), the larvae of which feed on the underground parts of the plant. This can cause the chimneys to become unstable and buckle. Infested plants should be removed and a new location for the tier onions should be considered.
Propagating stage onions
In nature, onions multiply by means of the brood bulbs that are attached to the stems of the plant. At some point the weight of the small onions is so high that the stalk snaps and the onions sink to the ground. There they root, sprout and form new plants.
Since the multi-storey onion does not form flowers or seeds, it can only be propagated vegetatively - either by dividing the mother onion or via the brood onions. You can simply let nature take its course and let the plant multiply itself, or you can harvest the bulbs and put them in the ground yourself. August is the best time to do this, when the onions are mature and strong.
Another method of propagating tier onions is by dividing the mother onion. In the course of storing reserve substances, the plant forms several secondary bulbs. These can also be dug up in autumn and planted individually in new locations.
Are air bulbs hardy?
Set onions are hardy and perennial. This means that they survive the winter well in the bed and will sprout again in the new year. If the winter is mild, the plant even stays green and you can continue to harvest the stalk-like stems.
If you have grown the multi-onion in a pot, however, it should be protected from frost by insulating it and placing it out of the wind.
Harvesting and using set onions
All parts of the air bulb are edible. Both the spring onions, the green chimneys,as well as the mother bulbs in the ground. This means that some of the tier onion can be used almost all year round. The green chimneys should not be harvested excessively, especially if the plant is still to develop onions. The onions formed between June and September can be harvested as soon as they have reached the desired size. Only in autumn, from the end of September, can the remaining onions be harvested and used directly or stored. These can be stored under suitable conditions - i.e. cool, dark and above all very dry - until next spring. However, only onions that have not yet sprouted are suitable for this.
In the kitchen, the spring onions of the tier onion can be used in many ways, but due to their size, they are ideal for pickling as silver onions, but also raw, fried or as an onion spice. Their taste is described as finely aromatic, hot and oniony, so that aerial onions are often used in pasta or as an accompaniment to meat and fish.
The green shanks are ideal as a substitute for chives or spring onions. In terms of the ingredients, stage onions are in no way inferior to ordinary onions. Due to the essential oils, using onions can have a positive effect on vascular diseases such as arteriosclerosis and high blood pressure.
Summary: Harvesting and Using Bunch Onions
- All parts of the stage onion can be used in the kitchen
- Harvest the chimneys all year round from the moment they sprout and use them like spring onions or chives
- Onions ready for harvest from July, they can be harvested for storage from the end of September. The onions can be used whole and pickled, fried or eaten raw in a salad.
Tip: We recommend not removing all the bulbils from one chimney in summer, but leaving a few on the plant, which may then form a next tier.
Are you a friend of unusual vegetables and like to experiment in your garden? Then we can recommend our article about curious vegetables.