If you want to grow onions make sure the pH is about 6.5 to 8.5 and that the soil is well-drained, firm, and not freshly manured. The onions can either be started off indoors as seedlings, but since there is almost no cost difference and it saves much energy and time, the onions are commonly started off with an onion set. These are small onion bulbs that are sold specifically just for planting.
Planting the Onion Set
In late March or early April, you can start to plant your onion bulbs. To ensure you have straight rows you can pull a string across the gardening bed, and push the bulbs into the earth just along the string. The bulbs should be about 10 cm apart, and the tips of the bulb should be showing. The rows should be about 30 cm apart.
Make sure you watch the freshly planted onions because birds like to peck them out of the soil. For that case keep a few extra bulbs and plant those when you notice that some bulbs have gone missing. If you find that the birds are too large a problem to fix with a few bulbs, it will be helpful to protect the onions with a bird netting.
If you find that frost pushes up your onion bulbs, push them back down to help them grow better. The frost will not harm the onion since it likes cool moist temperatures. Make sure you water the bulbs right after planting.
During the Growing Season
Periodically hoe the ground around the onions shallowly and make sure the plants are kept free from weeds to give them as many nutrients as possible. Fertilize the plants every month with a general fertilizer to give the onion enough nutrients. At this point, the bird netting can usually be removed since the green stalks will not be that attractive to the birds anymore.
Harvest and Storage
In late August and early September, it will be time to start harvesting the Onions. When the bulb is ready for harvest the leaves will bend over, but usually, you can just harvest them when you think the onions are large enough.
You can just pull up the onions you need for table use, or you can harvest all the onions at the same time. For the largest onion, it might help if you lift them up with a fork. If you want to enjoy the onions in the winter months, you should spread the onions on sheets of newspaper in a dry, warm place for about 2-4 weeks. This place should be sunny, but don’t let the onions get rained on or have dew falling on them.
This will make sure the onions are dry and will not rot when you store them in the winter. Once the onions are dry you can store them like store-bought onions in net bags, or in slatted trays, or you can tie the dried stems to string and you can hang them in a cool dry place. This method of storing will let you eat onions well into Spring.