Attention green thumbs: Here's how to garden in the winter, no grow lights required

Kath Smyth, with the Calgary Horticultural Society, says people can get started now on their gardening, no grow lights required — just a plastic milk jug, some seeds and some soil.

'This is called extending and using our season,' says Kath Smyth, with the Calgary Horticultural Society

Repurposed plastic milk jugs are covered in snow and acting as 'mini greenhouses' for the seeds. (Submitted by Kath Smyth)

It wouldn't seem like optimal weather to start gardening this week, with well below freezing temperatures. In Calgary, the forecast shows temperatures to hover below –20 C until at least Thursday.

Eager gardeners might be left feeling a bit restless as they count down the days until spring, but it turns out they might not actually need to wait.

According to Kath Smyth, with the Calgary Horticultural Society, people can get started now, no grow lights required — just an empty plastic milk jug, some seeds and some soil to make mini outdoor greenhouses.

"This is called extending and using our season," Smyth told the Calgary Eyeopener.

Smyth says it's called winter sowing and it's perfect for those who want an early start gardening.

A jug and seeds

First, you'll need a clean and empty plastic milk jug, Smyth says.

It can be a two-litre or four-litre container, or any clear takeout container with a lid.

If using milk jugs, toss out the cap so the plants can get moisture from the snow. If using a takeout container or clamshell with a lid, cut some slits in it so water can get in.

"They do need venting," Smyth said.

Punch six to eight holes in the bottom of the container for drainage. Then, make a cut about four inches from the bottom, leaving an inch near the handle area intact, acting as a hinge. 

Fill the jug with potting soil to a depth of 3½ inches and pat down into a smooth seeding surface.

Kath Smyth says the jugs can be placed in a snowbank and they should be out of the wind and out of direct sunlight. (Submitted by Kath Smyth)

After that, you can plant your seeds, ensuring you follow the directions on the package. Plants like spinach, kale and lettuce work well in cooler weather, she said.

"Space them out a bit," she said. "Don't just dump the whole package in."

Then, tape up the jug with duct tape and label it with the seed planted inside.

The next step might seem counterintuitive: place them outdoors.

Smyth says the jugs can be placed in a snowbank and they should be out of the wind and out of direct sunlight, though it's OK for them to get some sun.

"Over at the horticulture society in the gardens there, we tucked them in among the shrubs and along the fence line where the sun stays on them [in the morning] and they germinate," she said, adding they pick the spot so the snow will gather on them and create insulation.

'Little greenhouses'

Smyth says that as the days get longer, the sun and the insulation from the snow helps warm up the jugs.

"They create their own little microclimate and they get warm," Smyth said. "Then they start to sprout because it's like … its own little heated greenhouse."

And the bonus? It's great for lazy gardeners.

Instead of traditional methods, there's no period of hardening off plants — the slow exposure to the outdoors — since people don't have to bring them inside every night in the spring.

"Some people forget to do this and kill their plants," Smyth said.

Early harvest

Smyth says you can transplant the legumes as soon as the ground clears and the snow has melted off your vegetable garden and as long as conditions are right.

As well, do not open the jugs until transplant time. It's also possible to harvest around then, too, she notes.

Celery and lettuce, safe from the bitter cold, growing in cups inside a kitchen. Smyth says she also grows plants indoors but winter sowing in milk jugs helps keep her counter spaces less crowded. (Submitted by Kath Smyth)

"My lettuces are usually so big in April ... I'm already harvesting and eating them," Smyth said.

Winter sowing also helps in avoiding having potted plants overtake your indoor space.

"Winter sowing is taking advantage of not having to fill your kitchen counter, as I do with many plants," Smyth said.

"Right now, my kitchen counter is filled with roots that I've rescued from the garbage can. I'm growing leeks right now and onions and lettuces, and I've got celery."

As for planting tomatoes and peppers with this technique, it's best to keep them indoors or wait for spring.

"It's too cold for them," she said. 

With files from the Calgary Eyeopener.


  • This article was updated from a previous version as Kath Smyth said the jugs can get some sunlight. The original version said they should be kept out of the sunlight.
    Feb 09, 2021 3:24 PM MT


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