As I mentioned, some cannabis strains can handle the cold much better than other strains. If possible, it helps to pick a cold-resistant strain if you know that your grow area may experience chilly temperatures on a regular basis. Learn where you can get seeds.
However, in order to get most cannabis plants to start flowering (making buds), you need to give them at least 12 hours of complete darkness every day, which means grow lights need to be off for 12 hours/day. For some growers in a wintry climate, a 12-hour dark period (even during the day) will send the temperature plummeting too low.
Recommended auto-flowering strains for the cold
But you can capture that power indoors, too. If you’re growing in a basement or garage, it’s common for the floor to be cold. When that’s the case, put your plants on a tray or some other barrier to prevent roots from sitting directly on the chilly floor.
Cannabis plants thrive in the winter as long as you protect them from the cold
The ruderalis hemp plant (the ancestor of all auto-flowering strains) evolved in the freezing environment of northern Siberia
Let me elaborate a little more on changing the light schedule. It’s common to grow in a garage or attic that is an okay temperature during the day but too cold at night when the grow lights go off. In this case, change your plant’s light schedule so the grow lights turn on at night (during the coldest hours) to help equalize day and night temperature.
Modern autoflowering plants are ruderalis hybrids that have been bred for yields, bud quality, and potency, yet some strains still carry resistance to cold
Recommended cold-resistant photoperiod strains
Building upon what we said earlier, autoflowers can be perfect for less than optimal conditions outdoors. Most autoflowers will only spend 30 days or less in the vegetative phase, and will then start to go into flowering on their own. Their entire lifecycle from seed to harvest can be as short as 8 weeks. This way, you can plan your grow perfectly so that you can harvest right before frost or rainfall. What’s more, autoflowers don’t rely on hours of light exposure like photoperiod strains do. This means you can set them outside to grow and flower independently of the season.
Most of us are not so lucky as to live in a warm climate like Southern Europe or California. Growers in those locations can cultivate their ganja all year round without much trouble, but the short summers and long winters in our climate (Northern Europe) aren’t exactly ideal if we want to grow cannabis. Then again, growing cannabis in cold weather is possible if you know how to go about it. Even better, the chillier temperatures in our climate can actually have some advantages for growing weed.
On the other hand, LED lights can be a clear disadvantage in winter. Since they produce almost no heat, they can’t warm up your growing area as HID lamps do. This means you’ll likely require an extra heater so that your plants can thrive when it’s colder.
4. KEEP A MOTHER PLANT INDOORS
One difference to HID is that LED lights create significantly less heat. In general, this is seen as an advantage. During the warmer months of the year, LEDs won’t heat up your tent as much as HID, so you won’t need additional cooling for your grow room. Likewise, LEDs allow you to output lots of light and therefore maximise your harvest without risking heat stress or burning your plants.
To ensure your plants can survive any threat of frost, make sure to place them in a spot that gets direct sunlight in the morning. The reason for this is that it is better when plants can slowly defrost after a night of chill. This way, your plants may even be able to survive nights that drop below their healthy threshold for development. Growing spots near a lake or river can also be very good. They are naturally a few degrees warmer, so there is less risk for frost at night.
Tip: If frost is expected, water your plants in the evening. This protects the roots from freezing.
HOW TO GROW MARIJUANA IN COLD WEATHER
The problem with HID lights, however, is that these light fixtures create a ton of heat. This means that indoor growers often require special cooling systems in their grow room to keep the plants at a comfortable level. Not so during the colder months of the year! The colder temperature outside and the hot HID lights can make it so your plants can grow in just the right temperatures. This means no extra heating or cooling required for your grow room, which can help save a lot of money. Some growers take the colder months of the year as an opportunity to add more HID lights to their grow room for higher yields.
The same is true for CFL (fluorescent) grow lights that are still widely used for vegging. Just like LEDs, these lamps hardly create any heat, so you will possibly need some heating solution to keep your plants happy and healthy.