Onions grow underground and are biennial plants. You sow them one year, from which small onions will grow. You have to keep these cool and dry and then you can plant them in the spring.
For convenience, you can also simply buy seed onions at the end of winter. It is best to plant these around February / March, when the soil starts to warm up a bit. Onions grow quickly, and you can usually harvest them as early as June.
Plant the onions in rows about 8cm apart. The top tip of the bulb should be just above the earth. Try to leave about 30cm between the rows. You want onions to grow underground, so don’t overfert them or they’ll soon stick out above the ground. It is also best to weed the weeds by hand. Onions have shallow roots, which means that you can quickly damage the onions with a hoe.
Although the onions like water, they dislike soaking wet soil. Watering is very important. Because they grow and root superficially, they often suffer from drought quickly. You will not easily see it in the onion itself, they only grow less well if they do not get enough water. In drought it is best to water regularly, this ensures extra large onions. But beware! They really don’t like to be in soaking wet ground!
You know it’s time to harvest when the onion’s tops fall and dry out. You can then pull them out of the ground and let them dry on a rack. If they are completely dry, you can keep them for months!