Onions go well with a variety of dishes. Here you can learn everything you need to know about growing onions in your own garden.
The onion (Allium cepa) is one of the most popular vegetables. It belongs to the amaryllis family (Amaryllidaceae). Whether stewed, fried or raw, onion is simply a must in many dishes. Even if its origin is somewhat of an unsolved mystery, it feels very much at home in the temperate latitudes of Central Europe. In the following, we will show you how to grow onions at home, what you need to know about onion plant care and give you step-by-step instructions for onion harvest.
- Growing onions
- Buying onions vs. propagating onions
- Onion varieties: best varieties to grow and cook with
- Onion plant care
- Harvesting and storing onions
Although onions can be cultivated from seed, most gardeners prefer to simply put onion bulbs into the ground to grow them. This is more convenient and usually more successful. In the next paragraph, we will discuss what to consider when growing onions.
Planting onion bulbs: the right location
Onions thrive best in loess and clay soils. The balanced amount and constant supply of nutrients as well as the high proportion of humus make these soils the perfect location. Those without ideal growing conditions for onions can incorporate compost into their onion bed. The most important thing is to loosen the soil deep enough. Loosening up stimulates soil life and aerates the deeper layers.
Tip: Would you like to grow onions in a container or on the balcony? No problem! Just keep in mind to choose a container big enough for the new bulbs to form.
When is the best time to plant onions?
You should not plant your onions before the end of April. The bulbs contain a lot of water and are therefore sensitive to cold. At the end of April, there is a lower risk of night frost and the higher soil temperatures ensure rapid growth of the young plants.
Note: Most of the time, it is the “summer” varieties that are planted in domestic gardens. As described above, these should only be planted in April. Apart from that, there are also winter varieties you can plant in August. The first bulbs are usually harvested in late May.
How to plant onion bulbs?
Loosen up the bed before planting the bulbs. Plant them deep enough to just have the shoots sticking out of the soil. Plant at a distance of at least 15 cm in a row, leaving 25 cm between rows. Planting in rows also makes it easier to take care of your bulbs later on (while weeding etc.).
Summary: Growing onions
- Loosen up the soil; if necessary, mix in compost (preferably in autumn!)
- Sow onion seeds at the end of February or plant onion bulbs at the end of April
- Do not plant the onion bulbs too deep; their shoots should stick out
- Distance between rows 25 cm; distance within the row at least 15 cm
- Regularly remove weeds to prevent competition
Buying onions vs. propagating onions
Cultivated onions are the safest way for a lush onion harvest. You can buy onions in any well-assorted gardening centre or order them online.
Growing your own onion bulbs
After the first year of cultivation you can propagate your freshly harvested onions yourself. Simply harvest and dry the bulbs as described above. Alternatively, you can propagate them by division: Cut the tuber along the base of the shoot dividing it in the middle. It is crucial that both halves of the onion contain part of the shoot and root base, otherwise sprouting is impossible.
Note: The propagation of common store-bought onions is usually not very successful, as these vegetables have often been stored for a long time and also come from overbred varieties. During grafting, high-yield varieties and tasty varieties are placed on a resistant rootstock. Although it is possible to graft vegetables at home, this is very time-consuming and not always fruitful.
Propagating onions from seeds
If you want to see your onions grow from the beginning of germination, you can also buy onion seeds. The options are endless! A bag of onion seeds is very affordable and available either online or in well-stocked local shops. You can either sow your onions outside in February or grow them in small pots before planting them out.
Tip: In order to not complicate things, it is best to grow your onions from bulbs. They are affordable and usually promise greater success of harvest than seeds do!
Onion varieties: best varieties to grow and cook with
There is a large selection of onion varieties, which can easily become overwhelming to choose from. We compiled a small selection of different onion varieties, where we briefly explain their differences:
Smaller and spicier onion varieties:
- ‘Tonda Musona’: a white onion variety; very tasty; long-lasting; good for storage
- ‘Rossa di Toscana’: a traditional heirloom red variety from Italy; round shape; intense flavour
- ‘Zittauer Gelbe’: an heirloom onion variety; firm consistency; good flavour
- ‘Texas Early’: late-ripening yellow variety; bears larger onions; abundant yields and good aroma
Large and mild onion varieties:
- ‘Exhibition’: lush green shoots; high yield; aromatic; onions weigh up to 1.5 kg
- ‘The Kelsae’: an English variety; very mild and large; record harvest: 6 kg onion!
- ‘Alisa Craig’: an English variety; mild flavour; large onions (>700 g)
Onion plant care
The onion plant itself is easy to care for. However, there are a few things you should pay attention to to ensure a rich onion harvest. We will tell you what is important when it comes to onion care.
Onions are low to medium-yielding plants. Adding compost in autumn is the best way to enrich the soil with nutrients and positively influence its structure. After that, it is not necessary to add fertiliser. Alternatively, you can choose to fertilise in spring. In that case we suggest using a plant-based tomato fertiliser. The potassium contained in tomato fertiliser stabilises the cell walls extending the onions storage capability. Make sure to incorporate the fertiliser thoroughly as it will attract onion flies if on the surface.
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Onions prefer moist soil but should not be waterlogged. Depending on weather conditions, regular watering at longer intervals is the best way to provide your onions with an adequate supply of water.
Harvesting and storing onions
Onions are a classic kitchen staple and are used for cooking all year round. In the next section, we will discuss when to harvest onions, how to preserve and store them so that they last long.
The onions are ripe and ready for storage from the beginning of August. No gardening tools are required for harvesting the bulbs. Simply pull them out by the leaves and place them side by side spread out on the ground. Storing them that way, the outer skins of the bulbs can dry out over several days and thus become more durable.
Important: Turn your bulbs regularly while they are drying!
When the outer skins of the onions are dried, you can store them either hanging or lying. To hang the onions, simply tie the leaves together where they grow out of the bulb and hang them in a dark, cool and dry place.
Note: Do not store onions next to potatoes! Potatoes release a lot of moisture, which can be easily absorbed by dry onion skins.