Growing onions from seed


Hello,  I live in Owen sound, and have a vegetable garden. I’ve grown bulb onions for several years, and this year would like to collect the black onion seeds, and hopefully start them from seed next year. How do I do this?



Thank you for calling — this is a very good question.

Many/most vegetable gardeners grow onions from “sets”, which are small, immature onion bulbs. They’re easy to handle, plant and grow — period. But growing from seed lets gardeners choose from a wonderful list of varieties, from early-season sweet onions to late-season onions for keeping on hand longer. Onion colours range through the entire spectrum, in varying shapes and sizes. Further, from our research, most onion experts seem to agree that onions grown from seed perform better than those grown from sets. They are less prone to disease, they store better, and they bulb up faster.

So, first: if you plan on collecting seeds from your garden this year for planting next year, drOnion-Seed-Headsying them is very important, if you want them to be viable. Allow your onions to mature, blossom, and develop seeds. Spread the black seeds out on paper, and air dry for about a week. Then store in a dry and cool place.

Alternatively, if buying seeds, enjoy sourcing options from seed catalogues, and order varieties suited to your climate and zone. Onion varieties differ in the length of daylight, and the temperature, required to make a bulb. Onions in south-central Ontario require at least 14 hours of light to bulb up. The plant first grows foliage in cool spring weather, then form a bulb during warm summer weather, triggered by the long days.

Either way, with your own seed, or purchased, next spring, when seeding, purchase fresh seed-starting mix as a safety precaution against soil-borne diseases — delicate onion seedlings stay in pots for up to 10 weeks, and need to be hardy. Follow your seed catalogue directions to the ” T “, to ensure strong, deep-rooted seedlings that will then mature into healthy bulbs.

And for good reading for you, and our fellow gardeners, from the Ministry of Agriculture, Food and Rural Affairs, here is a link to their information on roots and bulbs, including carrot, garlic, horseradish, leek, onion, parsnip, radish, rutabaga, shallots, sugar beet, sweet potato and table beet.

All the best with your new foray into growing onions from seed !