Can You Grow Weed in Winter? A Cold-Season Outdoor Guide

Yes, you can grow cannabis outdoors in winter, as long as your winters are cool rather than freezing: start plants indoors, move them out in containers, protect them from frost and pick fast-flowering genetics. Winter harvests are smaller, but pests are rarer, and in mild climates like much of Argentina it lets outdoor growers keep a crop going all year. In other words, cold weather doesn't have to stop you from growing cannabis year-round. Sure, the ideal time to grow most cannabis seeds is when it's warm and the days are long, which is what the plant needs to grow and develop properly. But winter grows are doable, and for outdoor growers they're a way to run a full yearly cycle with one big upside: far fewer pests. There's a downside too: lower yields. You can make up for that by adding more plants. You just need to keep a few things in mind to pull off a winter grow, whether you're in Argentina or anywhere with mild winters.

Plenty of people wonder which plants do best in winter. It might not seem like it, but there are a lot of them.

Just as some plants need long, sunny days to thrive, others aren't big fans of the heat and actually need the cold to grow strong and nutritious.

So what can you grow in cold, rainy, windy weather? The classic winter vegetables are the brassicas, a huge plant family that includes cabbage, broccoli, cauliflower, arugula, turnips and mustard greens, among many others.

What you grow will always depend on how much space you have. If it's not much, say a container or a small balcony or rooftop garden, go for winter lettuce varieties (Argentine growers favor types like Española, Reina de Mayo and Marina), plus arugula, mizuna (Japanese mustard greens), cilantro, oregano and chives.

You can add spinach and Swiss chard to the winter lineup, and if you've got a bit more soil, radishes too.

If you have a good amount of garden space and fertile soil, your options open up: cabbage, cauliflower, kale, broccoli, bok choy, Swiss chard, onions, carrots and even legumes.

There are lots of brassicas, but not every winter crop is one, and many plants can't handle frost: that early-morning cold that settles as ice crystals and tends to burn plants that aren't built for it.

To prevent frost damage, cover your plants with plastic, frost cloth or a low tunnel, which is just wire hoops with plastic stretched over them. In a small garden, an upturned bottle or jug over each plant does the trick, especially when it drops below freezing. The key is that the cover never touches the plant, or it'll burn or freeze anyway. Once the frost passes and temperatures rise, take the covers off and let everything air out.

Growing weed in winter: what you need to know

You can also run fall-winter cannabis grows, but when should you start? In Argentina and the rest of the Southern Hemisphere, March or April is a good time (that's September or October in the Northern Hemisphere). Your summer harvest makes a handy reference point: as you harvest, you can put out seedlings you germinated ahead of time, or germinate straight in the container. You can still germinate in May and June (November and December up north), but if it gets really cold, the plants may barely develop or not make it at all. You can even start as late as July (January in the Northern Hemisphere), but then you'll need very fast-flowering plants. And when we say cold, we don't mean below-freezing temperatures all day for long stretches, because almost nothing grows in those places. We mean climates where winter averages around 5 to 10 °C (41-50 °F), like much of northern Europe and North America, or countries such as China, Pakistan and northern India, where some mountain regions stay cold year-round. Those are exactly the places some of the best seeds for cold climates and cold seasons come from. So if some of today's best seeds come from those regions, it's because growing cannabis in winter really is possible, especially since a lot of the genetics on the seed market originated in climates like these.

Tips for growing cannabis in winter

Seeds:

If you're starting from seed, germinate indoors in any winter month. Germinate with plain water at 18-22 °C (64-72 °F).

Seedlings:

Keep seedlings indoors until they've put on enough growth. If you're working with clones, there's no rush to move them outside; you can veg them for about 30 days. Once you move your plants outdoors, they'll most likely start flowering, because the short winter days hit them with a photoperiod shock.

Lighting:

Following on from that, if you want to stretch the photoperiod so the plants keep growing, you'll need indoor lighting, such as LEC (light-emitting ceramic) fixtures.

Containers or in-ground?:

Containers are your best bet, especially for an outdoor winter grow, because they give you better protection from the cold. Plants growing directly in the ground are harder to keep warm if the soil itself is cold. You can also lay down a ground “blanket” made from heat-absorbing material, like a layer of limestone. Vineyards use this a lot to even out the temperature swing between day and night. If there's frost, it keeps the roots from freezing.

What about pests?

Pests do show up less often in winter, but humidity can always bring trouble, especially mold and fungus. Preventive fungicide treatments are always a good idea, especially in the rainy season.

The best way to harvest:

Staggering your harvest is a smart move: if an unexpected frost hits, you won't lose the whole crop, and you'll have buds ready to harvest over a longer stretch. It also means you can work in less space than if you planted all your seeds at once.

How do you keep temperatures up?

Growing weed in winter means keeping temperatures where the plant needs them. Heaters and thermostats really only make sense in greenhouses. To keep the temperature right for each growth stage at all times, your best move is to put one thermometer in the growing medium (root-zone temperature) and another in the greenhouse (air temperature) , so you always know where you stand and can switch on a heater when needed. If the medium is very cold, warm your watering solution to 18-22 °C (64-72 °F) before you water. You might also like...