The Tricks To Growing Onions Successfully


Growing onions for cooking or fresh use are best started early indoors to get a good jump on the season.

They can be sown directly into the garden but the crop will simply be a little later.

There is a myth in the gardening world that home gardeners need to purchase "sets" to get a good crop. Professional market gardeners simply sow seed for their main crops.

row of onions

A nice row of onions (and carrots)

The Trick


The trick to sowing direct into the ground is to sow early. Seed that is not in the ground by the first week of May will not normally mature before frost. So, look for a late April sowing to get those onions up and growing well from seed.

Sowing indoors is easily done. Take a flower pot, sprinkle onion seed on it so the seed is approximately 1 quarter inch from each other, cover very lightly with soil, water with warm water and give full sunlight.

The seeds will sprout very quickly if they are not too warm (this is a seed that I wouldn't put on a heating mat but just leave at room temperature). Grow them on with half strength plant food and full light until early May when the rapidly growing onions can be carefully transplanted into the garden.

For Large Roots


If you want your roots to be really large or really early, (such as specialty Spanish onions), then I'd buy sets and plant these in late April as well. But for general use such as cooking, go with seeding or home sowing.

Outdoor Sowing


Outdoor sowing usually puts the seeds one half to one inch apart (it isn't rocket science so you don't have to measure – just be close) and one quarter inch deep. Note that deep sowing will simply kill the seed. Rows for growing onions should be approximately 12 to 18 inches apart if you are using a thick seeding rate. You want to encourage air circulation in the garden to reduce or eliminate fungal problems.

When the growing onions start to touch at this close spacing, thin out and use the smaller tender onions in cooking or pickling. This leaves the remaining onions adequate space to reach two to three inches in size.

Feeding For Success


This is a shallow rooted vegetable so feeding early in the spring combined with a mid summer feeding of liquid fish emulsion or other liquid organic fertilizer will give you excellent results.

This is over and above the normal application of compost in the spring. This shallow root system also means that you have to be careful with irrigation; you should not allow the growing onions to get too dry during the heat of the summer or you'll set them back. Again, drip irrigation is ideal but overhead will work fine.

Harvest your onions as you need them through the season. Harvest by thinning the plants as they mature and grow into huge specimens. You'll be able to store them much more efficiently if you "cure" them in the garden before you bring them indoors.

About The Tops


There's a lot of advice about knocking over the tops of bulbs to make the bulb grow larger. Generally I understand the reason you knock the tops over is to prevent heart rot if there is heavy rain just before you cure the bulbs. If there are no heavy rains forecast (and the bulb will not be absorbing excessive amounts of water) there is little reason to knock over the tops.

Book cover Vegetable Gardening

Curing Onions Before Storing


To cure the bulbs for storage, pull the bulbs out of the ground and allow them to sit on top of the soil for 7 to 10 days to "cure". Avoid leaving them to be exposed to frost. Leave the soil on the roots to dry out naturally.

The neck will dry out during this time and you can remove it just before storing the bulbs. You can also clean the soil from the roots at the same time as the dried out necks are removed. (necks are the long leaves that will wither down when pulled from the soil -you'll understand when you see them) Do not cut into the green growth of the bulb before storage.



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