Four Simple Methods To Start Onions From Seed

Growing onions is super easy and inexpensive. They cost just a couple pennies per onion seed, require little water to grow well, no fussing required.

Many gardeners start their onions from sets (basically dormant baby onions) they get from the nursery in spring. They are easy to plant, just push into the ground about an inch, water once a week, watch them grow.

The biggest drawback with sets is the lack of variety as they tend to just come in white, yellow, red, or multiplier. Sometimes they are not the freshest either, so you get dried out duds in the package, and I find that not all the onions break dormancy, basically do nothing at all.

Onions grown from direct sown seeds.

I started growing my onions from seed by fluke and out of necessity many, many years ago. I broke my left wrist badly enough that I needed pins and a cast to hold it in place, so driving my standard/manual SUV to the city for shopping was not happening. I, luckily, happened to have onion seeds at home that I had ordered on a whim that year. I decided to direct sow a few rows of seeds and hope for the best. They turned out to be the best onions I had ever grown! Best germination and size. This was in my Zone 2/3 garden just outside of Edmonton. See them in the potager bed above.

I have been growing from seed ever since. I love all the selections available to me, all colours and kinds and most importantly, I can choose where I order the seeds from, to make sure that I am buying from a company that has taken the 'Seed Safe Pledge'.

Ordering tips!

1. Buy fresh seeds annually as they do not keep well.

2. When ordering seeds, make sure that you are getting long-day seeds in Canada and the northern States. They like our long summer days whereas short-day seeds will just go to seed with all the hours of daylight we get up here.

3. Make sure to check how long the onions store in your pantry if you are looking for keepers. Some of the sweet onions, like Walla Walla and Spanish, do not keep very long (2 months). This year, I am growing Red Wethersfield and Yellow of Parma, both are really good storage onions at 8 plus months.

Okay, let's get to the good stuff. Here are FOUR ways to start your onions from seed.

Onion and cabbage seedlings in my potager.

1. Winter Sowing

The time to start growing onions from seed is right now, late January or early February. Winter sowing is super simple and does not require much by way of supplies. Sow them now and they sprout when the conditions and timing is right. They do it on their own time.

Use 4 litre milk jugs for this, pastry clamshells, salad green containers, pop bottles, or those roasted chicken containers that come with a clear lid. See here for more information about what winter sowing is...

My preferred potting soil. It also comes in small bags.

Poke holes into the bottom of the container for drainage and cut milk jugs in half, leaving one side intact. Check out this link about winter sowing for pictures.

Fill bottom part with a good soilless potting mix, like Sunshine #4 or ProMix HP.

Do not water.

Scatter seeds on top of the dry soil, press in lightly. If using a bottle or jug, leave the lid off for ventilation, if using a clamshell, poke holes into the top cover.

Label the container with what you planted!

Place outside in a shaded spot outside, in the snowbank is fine, does not matter if it rains or snows on them. The onions will stay dormant till the time is right. When the days are long enough and warm enough, the onions will begin to sprout.

When you see sprouting, give them some water and then as needed to keep the soil damp. Keep it in the shade so that you do not cook your seedlings. As days get warmer in spring, open the tops during the day, close at night.

Each time the green tops grow to 3 inches tall, cut them back to 1 inch tall. This will encourage bigger, better bulbs.

Feed with liquid seaweed or kelp every couple of weeks.

2. Starting Indoors

This method requires a bit more equipment. You need bottom heat from a heating mat and good, bright lights.

Start seeds in flats, trays or 6 packs in February for planting out in late spring.

Use a soil-less potting mix, with some compost added in. Do not use garden loam in pots or trays.

Scatter seeds, lightly cover with your compost mix to about 1/4 inch in depth, water in.

Place on bottom heat till you see shoots for faster germination, or simply place in a sunny spot and they will come up just fine. Keep soil moist.

You should see the tops popping through in about a week's time. Take off the heat, if using it, and place under the lights.

Each time the green tops grow to 3 inches tall, cut them back to 1 inch tall. This will encourage bigger, better bulbs. Feed with liquid seaweed or kelp every couple of weeks.

They will be ready to go into a cold frame in late April to harden off and acclimate and then into the garden beds in May. April if you are in a warmer zone. They can take light frosts and are even fine in snow!

3. Direct Sowing

This is my favourite way. Given a choice, I am always going to choose direct sowing. It means no fussing with pots, potting soils, lights, heat mats... just popping the seeds directly into the garden bed.

The biggest drawback with this is, of course, the timing. Onions take 80 to 105 days to go from germination to harvest so need to get into the potager early enough. In my zone 3 garden, I will be sowing on a nice day in early May. They can handle light frosts, snow, rain, and cool-ish temps so no need to wait till last frost.

As mentioned, I did it when I broke my wrist, with great results, so should be able to do it again. If you are in a warmer zone (maybe you're a follower from the island - zone 7), no reason not to sow in April, or even May, as your late summer gives you plenty of time to harvest.

Soak seeds for 12 to 24 hours to help them germinate much faster. Sow in a weed free bed with really great soil that has been amended with compost or manure.

Sow in very shallow furrows, covered with 1/4 inch of soil, 3 inches apart for no thinning. If you don't mind thinning, or want to eat every second onion as baby-sized, sow 2 inches apart. Seeds are large and easy to work with.

Plant rows 6 inches apart. Keep soil moist till you see germination.

4. A Twist on Starting Indoors ..No lights? Have a Greenhouse?

This is the way I grow mine. I do not have lights, do not want to buy lights, hah!

This is a twist on the indoor starts but maybe you have no lights? Maybe you have a greenhouse that you can heat in the cusp seasons? Or a cold frame and frost blankets?

-Start seeds indoors on heating mats, as mentioned above, in February. Once they have germinated, take off heat and place in a bright, cool window.

-If your greenhouse is heated, place them out there, keep greenhouse just above freezing, ideally at 5-10°C (40-50°F).

-Leave in the bright, cool, greenhouse, water and feed as above.

-If you have no heated greenhouse, keep indoors, in a bright window until temps are higher and you are no longer getting super hard frosts (March on the island/April in zone 3).

-Cover at night with a frost blanket, or bring indoors for the night.

-I have a coldframe (mini greenhouse) in my unheated greenhouse so I pop them in there. They stay cosy and warm, till I plant them out.

Picture from Ben at Higgledy Garden Seeds. Use clear totes as a mini greenhouse.

Part two, coming soon, is everything you need to know about planting and growing for a successful harvest of really great onions.

Happy Growing ~ Tanja