Planting, caring for and harvesting multi-layer onions

The single or air onion is rarely found. With its striking appearance, the versatile plant parts and the easy care, it is an asset to any garden.

The single onion (Allium x proliferum or Allium cepa var. viviparum) is a bit strange to look at: The small onions do not form underground, but above ground on stalks, where they sprout directly and thus form several "levels". This is the fact that the multi-level onion owes its name to. But the air onion not only has 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 tier onions, from planting to harvesting and using them.

Multi-layer onion: origin and characteristics

The single onion, also called air 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 air onions can be harvested all year round. The plants can be up to 80 cm high and form small bulbs (bulbils) instead of flowers from June to September. It happens not infrequently that these sprout on the stalk and thus form a second, sometimes even a third floor. When summer draws to a close, the stems snap off and the bulbs sink to the ground. There they take root and thus ensure the reproduction of the mother plant. This is also reflected in one of the Latin names: „Viviparum”Means roughly“ giving birth to life ”.

Plant multi-layer onions

Floor bulbs can be purchased from specialty shops. Often, however, the small bulbs are also passed on from gardener to gardener. Stack onions cannot be grown from seeds because the plant does not flower and therefore does not form seeds.

Multi-layer onions are poor eaters and have very low demands on the location. They prefer sunny to partially shaded locations on calcareous, humus rich and loose soils, the pH of which should be above 6.5.

Important: Leave a cultivation break of at least 4 years between planting the single onion and others Leek plants such as onions, leeks and spring onions, otherwise it can lead to crop rotation diseases come.
You can also grow air onions in a pot with a volume of 10 liters or more. We recommend our Plantura organic tomato & vegetable soil, as it has a loose structure and a high potassium content - both are important for healthy, aromatic onion plants. In addition, the earth is peat-free and is sustainably produced in Germany. The soil should be made lean by adding 30% sand, which also ensures better water drainage. The best time to plant multi-level bulbs is either in late summer from August.

Planting bulbs step by step:

• Prepare the bottom of the bed well by removing weeds and chopping it up.
• Soils in our regions naturally acidify over time. One factor that reinforces this natural process is fertilization, for example. So it can be helpful to have some lime, like ours, before planting Plantura organic lawn & garden limeto work into the soil. If you are unsure whether liming is necessary, you should first use the Determine the pH of your soil.
• Place the bulbs on the ground at a distance of 30-40 cm and press the bulbs lightly. Alternatively, you can stick the onions about 5 cm deep in the ground.
• In the following period 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 starts to rot and does not sprout.

Tip: It is best to use bulbs for planting that have not yet sprouted and that look healthy. So the chances of good growth are greater.

Proper care

Multi-layer onions are easy to care for. Like all onions, they are poor eaters and usually do not need any fertilizer. Particularly with nitrogen-based fertilizers, one should be careful: 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 spring. Potassium is also an important plant nutrient which, for example, plays an important role in the water balance and makes the plants more stable, disease and frost resistant.
Air onions only need to be watered during prolonged dry periods.
Especially at the beginning of growth, it may be necessary to remove weeds from time to time around the growing bulbous plants.

Tip: Old and withered leaves can be removed regularly to make room for new stems. The onion fly (Delia antiqua), the larvae eat on the subterranean parts of the plant. This can make the chimneys unstable and kink. You should remove infested plants and think about a new location for the multi-bulbs.

Propagate the onion

In nature, multi-level onions multiply via the setting onions that sit on the stems of the plant. At some point the weight of the small onions is so heavy that the stem kinks and the onions sink to the bottom. There they take root, sprout and form new plants.
Since the multi-level onion does not produce flowers or seeds, it can only be propagated vegetatively - either by dividing the mother onion or using the brood onions. You can simply let nature run wild and let the plant reproduce itself, or you can harvest the onions and put them in the ground yourself. The best time for this is August, when the bulbs are ripe and strong.
Another method of propagating multi-level onions is to divide the mother onion. In the course of the storage of reserve substances, the plant forms several secondary bulbs. These can also be dug up in autumn and individually planted in new locations.

Are aerial bulbs hardy?

Single onions are hardy and perennial. This means that they survive the winter in the bed and sprout again in the new year. If the winter is mild, the plant stays green and you can continue to harvest the chimney-like stems.
If you have grown the multi-onion in a pot, it should be protected from frost by isolating it and placing it out of the wind.

Harvest and use multi-layer onions

With the air onion, all parts of the plant are edible. Both the broiling onions, the green chimneys and the mother onions in the ground. This means that some of the multi-layer onion can be used almost all year round. The green chimneys should not be harvested excessively, especially if the plant is still to develop brood bulbs. The bulbs 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 immediately or stored. Under suitable conditions - that is, cool, dark and above all very dry - these can be stored until next spring. However, only onions that have not yet sprouted are suitable for this.

In the kitchen, the set onions can be used in a variety of ways, but they are suitable because of that Their size, for example, is ideal for pickling as silver onions, but also raw, fried or as Onion spice. Their taste is described as finely aromatic, hot and onion-like, so that air onions are also often used in pasta or as an accompaniment to meat and fish.
The green chimneys are ideal as a substitute for chives or spring onions. In terms of ingredients, multi-onions are in no way inferior to ordinary onions. Because of the essential oils, the use of multi-onions can have a positive effect on vascular ailments such as arteriosclerosis and high blood pressure.

Summary: harvest and use multi-level onions

• All parts of the multi-layer onion can be used in the kitchen
• Harvest chimneys all year round from the shoot and use them like spring onions or chives
• Onions ready for harvest from July, from the end of September they can be harvested for storage. The onions can be used whole and pickled, fried or eaten raw in a salad.

Tip: We recommend not to remove all bulbils from a vent in summer, but to leave a few on the plant, which then possibly form a next floor.

Are you a fan of unusual vegetables and do you like to experiment with something in your garden? Then we can send you our article about strange vegetables recommend.