Cannabis grows best when the plants receive plenty of warmth and sunshine. That said, there are cold weather weed strains that will tolerate low temperatures and with knowledge of suitable plant types and careful planning there’s no reason why cannabis can’t be grown in Northern climes, either indoor or outside.

Indoor v Outdoor

Both have their advantages. Outdoor growing benefits from free soil, free light and water (providing it rains). However outdoor growing is at the mercy of the vagaries of the weather and pests.

Indoor growing offers control and consistency of the crop through a tightly controlled growing environment but at the cost of artificial light, temperature and often expensive watering systems. Indoor grown plants generally produce a flower with higher THC levels.

Whilst plants need warmth and light, careful selection of plant types with short crop cycles can provide a solution to those living in northern latitudes with short growing seasons. A great example would be Auto Mazar with a short 100 days from seed to harvest.

Privacy may be a deciding factor in the outdoor v indoor debate. If you’re living in a city with close neighbours then indoor might be the best option.

There are some that say that some of the drawbacks of outdoor growing are mitigated as they consider the taste, effects and aromas of outdoor grown flowers are superior to indoor grown plants.

Don’t underestimate the benefits of greenhouse it can offer a viable compromise between the benefits a strictly controlled indoor environment and the cost benefits of outdoor cultivation.

Using relatively inexpensive heat mats can maintain the soil temperature above 12°C. The glass will provide a degree of control of the watering and even on a very cold icy but bright day, the inside temperature of a green house can be more than enough for your plants to remain healthy.

Make sure you keep the greenhouse well ventilated though to inhibit mold growth.

If your area gets enough sunlight there’s no reason why a greenhouse couldn’t allow you to grow cannabis all year round.

How cold can you go?

The answer is 12°C, any lower than this even cold weather weed strains wont survive. A soil temperature below this and the plant starts to shut down, it struggles to take in nutrients and water to the point it will wilt and produce stunted growth.

Roots are particularly susceptible to low temperatures. The ideal temperature for healthy root growth is between 15-20°C. One way round this is to start plants off as seedlings indoors and slowly acclimatise and ‘harden’ them off before planting them out.

Moisture and cold air are the perfect combination for mold growth especially on days with little wind. Once mold takes hold, it’s extremely difficult to combat without preparatory treatments. Mold can cause plants to rot resulting in a lost harvest.

Flowering plants however will prefer slightly cooler temperatures as in their natural state; they’re usually flowering in the Autumn. Indoor growers generally bring down the temperatures during the bloom phase as this can help promote bud development.

What the best cold weather weed strains?

Northern Lights Auto
Northern Lights Auto

It’s obvious, but by picking the best cold weather weed strains you will make your winter growing much easier. Ideally those native to Eastern and Northern Europe and Russia as mother nature will have done all the hard work in producing cold tolerant varieties.

Indicas tend to have shorter bloom cycles than Satvias, ideal if you’re looking to grow outdoors. Also look for auto flower varieties, as they are often ready to harvest outdoors after 80-100 days after germination. Northern Lights Autoflower is suitable as an outdoor cannabis plant. It is successfully grown outdoors in Denmark and Holland and can be harvested as late as October.

Mango Kush Auto is a hardy variety. If grown outdoors it takes around 100 days from seed to harvest. It would be possible, especially using a greenhouse to get two crops during the typical northern Spring to Autumn. It’s also quite small only reaching 75cm–100cm in height making it ideal for greenhouses.

 6 Golden Rules For Growing in Colder Climates

  1. Choose a suitable cold weather weed strain to grow with. Growing with sativas that are indigenous to hot humid environments just isn’t going to work. Pick Indica or autoflower strains that are naturally from colder environments.
  2. Control Humidity – This is particularly important in colder conditions. It might be difficult to control humidity if growing outdoors but keep an eye on your seasonal and local conditions and factor these into your planning.
    Even the simple step of positioning your plants where they get the morning sun to evaporate morning dew might be enough.
  3. Bud rot caused by mold is your enemy so try to position your plants where they will get as much sun as is available and where there might be a breeze.
  4. Maintain a Constant Temperature – Differences between day and night time temperatures can be extreme. Try to avoid temperature swings. Ideal temperatures are 20-25 degrees. Easy enough to maintain if growing indoors through heat lamps but can still be achieved if growing outdoors through timing your planting or using a greenhouse.
  5. Cultivate your seeds indoors and slowly acclimatise them and ‘harden’ them off before planting out if growing outdoors.
  6. Know the Warning Signs – Your plants are living things. Fail to feed and nurture them and they’ll let you know when they’re not happy. Signs to look out for include:
        • Growth slows or stops
        • Leaves or the connecting stalks turn brown or drop off
        • Leaves turn yellow earlier than expected
        • Leaf edges curl.
        • Spotting these signs early enough will allow you to attempt to rectify the issue.

Control Your Nutrients

If growing outdoors, building a healthy ‘living’ soil bed is essential as it will naturally provide the right nutrients in the right quantities the plant needs. It will also help with pest control and diseases. However, when growing outdoors, cooler temperatures below 10ºC will slow and even stop the uptake of nutrients.

In contrast, too many nutrients may cause nutrient burn causing the leaf tips to brown and curl.

Control The Lighting

Good strong sunlight can’t be beaten given its broad light spectrum, however if you’re growing indoors LED lighting provides the ideal lighting given its optimised spectrum and longer life and it is incredibly cheap to run. However, don’t forget that the older HPS and HID technologies do have the advantage that not only do they provide light, they also provide a lot of heat. Two conditions for growing for the price of one.

Final Word

If you are tempted to grow outside, keep a plant or two indoors. Even with the best planning and efforts, mother nature is unpredictable and frost, animal and pest damage can occur so better to be safe than sorry, if the worse happens, then you’ve got a back-up ready to go.

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