How to ignite onions

Growing onions - caring for onion sets

Growing “boring kitchen onions” in the garden is a good idea: onions are versatile, healthy and can be stored for a long time, making them one of the most valuable vegetable plants - no wonder that the ancient Egyptians regarded them as a sacrifice and means of payment. It is also a good idea because special types of onions in particular are very easy to grow in the home garden. They don't even exist as onion sets (but their care is also important), they are sown as normal and from then on they are actually always easier to care for, right up to “automatic propagation” by brood onions.



  • Onions ‘are actually asparagus’, no joke - they belong to the asparagus-like order
  • Within those, to the Amaryllis family and to the genus Leek, to make it a little more confusing
  • Our normal kitchen onion is scientifically called Allium cepa
  • The genus leek, allium, includes other types of onions
  • And a variety of edible leeks such as chives, garlic and leeks
  • This diversity is probably much greater than the species already cultivated suggest
  • Because the onions (and leaves) of Allium plants are probably all edible
  • However, only a good half a dozen of hundreds of species are grown by humans ...
  • The Allium cepa itself hardly grows in the wild anymore, it is almost only available as a cultivated plant


The kitchen onion has been grown in Germany for so long and so frequently that we know around 50 different names for it, from the Bolle to the Ulk to the Zipolle. Even if the homeland is probably further south (you don't really know because the ancestry has not yet been clarified), onions seem to feel comfortable with us without any problems ...

So it is, the onion has some demands on the soil, but otherwise fits into almost any environment that is reasonably sunny and warm, with little care. Warm means that onions should be grown in rough locations in very sunny locations, where they can still enjoy some protection or benefit from a favorable microclimate - it is not for nothing that the main commercial growing areas of German onions are all in warmer regions.

Natural varieties of onions multiply by sowing. Since onions grow into tall, slender plants in the upper area, which develop beautiful, large umbels with up to 100 individual flowers, you could do without creating a “proper” onion bed. Simply use onion cultivation as a garden design element: In an area with herbaceous ground cover (onions get along very well with oregano, for example), scattered onions are planted, ideally “Allium cepa var. Aggregatum” varieties such as the shallot, which in contrast to the "common" kitchen onion Allium cepa var. cepa forms several onions and brood onions. So you can harvest and also watch how your onions multiply automatically by daughter onions.

The floor

In Germany, onions are z. B. in Thuringia around Erfurt, in Upper Franconia around Bamberg and in the Palatinate, everywhere there are sandy loam soils. This prefers the onion, and the soil should be fine crumbly, but well set. If basic soil cultivation (e.g. loosening) is necessary, it should therefore be done in the autumn before onion cultivation.

Onions need quite nutritious soil, but they cannot tolerate excess nitrogen. So far only synthetically fertilized soils should either be subjected to a soil analysis, mostly they are overfertilized and first have to be “emaciated” (you can find out how to do this in articles on soil remediation). If onions grow in soil that is too nitrogenous, they mature poorly and tend to develop more foliage than onions.

The soil should be provided with ripe compost in the autumn before cultivation, onions do not like fresh or freshly fertilized soil.

Temporally variable growths

Onions are diverse, especially in terms of cultivation times and periods, first you have to decide between summer onions and winter onions:

The kitchen onion that you usually tearfully process on the kitchen table is the allium cepa, which only experiences summer. It is made to grow sometime in spring and harvested sometime between August and October and is therefore called summer onion.

The Allium cepa can also be cultivated over the winter, these onions are sown in August, ripen in the next spring and are therefore called winter onions (not to be confused with the winter onions “Allium fistulosum”).

Stick, sow, plant?

The onions are also variable in the way they are grown, as there are three different methods to choose from:

1. As the name “onion set” suggests, plugging is a classic cultivation method, and there is a reason. The weeds can be fought more easily in neat rows, onions only stay in the bed for a short time and are ready for harvest as early as July. The small onions can already be treated during cultivation so that they do not shoot later (form flowers), this is done by a so-called kiln at temperatures between 30 to 40 ° C. All advantages in commercial cultivation and therefore commonplace.

You can buy ready-made onions in spring, which you can pin in March or April depending on the region, which is how it works:

  • You get a piece of wood and “perforate” the bed
  • So deep that each onion sinks to a depth of about 4 cm
  • You should still just be able to see the tip
  • Row and plant spacing depend on the desired bulb size
  • The closer, the smaller - anything is possible between 20-50 cm per row and 5.15 cm per plant
  • Depending on the region, you can bring in the first onion harvest from July

2. Onions can also be sown. Like every plant (not yet made sterile by breeding), an onion also reproduces via seeds in order to enable genetic variation and thus adaptation to its environment (evolution).

Onion seeds are offered under the slightly confusing name of pickled onions, the sowing goes like this:

  • Start from mid-March to early April, depending on the region, when the ground has dried
  • Create seed trenches (in the case of “disordered” sowing, seed pits) with a depth of 1-2 cm
  • Row spacing 25-40 cm, plant spacing 5-15 cm
  • Sowing density affects onion crop size
  • If you are looking for a bumper crop, you can plant up to 120 onions per m²
  • Depending on the date of sowing, variety and region, harvest maturity between August and October

3. Onions are only grown from a few varieties that are popular in the trade and are then grown in bulk. If you want to grow old, exciting onion varieties, you can look for young plants instead of onion sets. They are raised from the cultivars that make the bulbs, so you get clones that have exactly the same characteristics as the parents (skin strength, tolerance to downy mildew ...). Young plants, like onions, have the advantage that foreign growth is easier to remove, with organic onions you should also have less to contend with diseases, while onions are often sold with a fungal pathogen in them.

Even if it's called onion sets - for home gardeners there is little reason to do the cake with the stick. Only a few varieties are grown into onions, and the onions that grow in this way do not keep as long as the onions that are grown from seeds. Direct sowing may result in one or two failures, but you can cope with that in the home garden, but you can grow very special, old varieties from seeds (or young plants), which then also bring a very special aroma into the kitchen.

Watering, fertilizing, maintaining

Like all plants, bulbs need regular watering as they grow so that there is always a little moisture in the soil. Like all land plants, they don't want to stand in wet soil that will cause the roots to rot. With onions, however, there is the special feature that, especially with late storage onions, irrigation is stopped in the time shortly before harvest, the drier onions are harvested, the better they can be stored.

If you have prepared the soil well in autumn, the onions no longer need fertilizing. In very poor soils, ripe compost can be added in season, never fresh manure, which attracts onion flies.

Onions do not like competitive vegetation so much, if the ground between them is not planted with oregano or the like, weeding or the use of the hoe is the order of the day. When the bulbs are of a certain size, you can pile them up a little, this also protects against competitive growth and also makes the bulbs a little larger.

Harvest and storage

The earlier you harvest onions, the less suitable they are for storage. The first will be the winter onions that were planted in the previous year, followed by the set or planted spring onions, then the seed onions or varieties planted later.

The early onions can each be harvested fresh for processing. In the case of varieties with several onions, you can “dig” and only harvest a part and leave the rest in the bed.

You can harvest a few onions for the kitchen at any time once they have grown into onions. Storage onions should be harvested when they are ripe; they are ready for harvest when around two thirds of the leaves are wilted. Storage onions should also be harvested as dry as possible. They are not watered the last time before harvest and are pulled out of the earth with leaves in dry, sunny late summer weather. Storage onions remain on the bed as long as there is no rain threat, they dry off there and thus become much more durable. So they can pre-dry in the garden for up to ten days, are then collected and dried in the storage room, turning them occasionally.

The storage room should be dry, cool and airy; When the onions are completely dry, you can braid a handful of onion plants on the foliage and hang them up (or simply tie them together if you are not a braiding artist).

"Dry, sunny late summer weather" is a rather theoretical instruction that late summer weather does not always obey. In the past, the onion foliage was bent over when the weather wasn't cooperating. This is no longer recommended today, onions that have not ripened on the leaves have a much shorter shelf life. If you want to accelerate ripening because bad weather is forecast, you should rather use a digging fork to lift the bulbs (with leaves!) Out of the ground, just enough to tear off some of the roots. Then the onions stop growing and ripen almost naturally ’and very quickly.

frequently asked Questions

Which types of onions are best for growing in the home garden?
“Allium cepa” is already available in many varieties and several breeding groups: The Allium cepa var. Cepa (common kitchen onions, of which there are the onion sets) in an incredible number of varieties, but not the most exciting varieties for the private garden. These can be found in the second group, Allium cepa var. Aggregatum, the onions that are capable of propagation by brood onions, shallots and almost forgotten species such as the potato onion, for example. There are also other interesting species, winter onions (Allium fistulosum) and pearl onions (Allium ampeloprasum pearl onion group) z. B. that do well in the garden.

Can I propagate onions myself?
Yes, of course, you can get bulbs to flower and seed (they need a certain special treatment, instructions are also available on the Internet) and sow the seeds. Or you can inquire about the types of onions that form bulbs, these types can then be propagated through them. But of course also through seeds, if at some point you develop the ambition to further develop rare onion varieties through breeding.