Think you can't grow cannabis just because it's winter? Think again! With the right setup, you can successfully cultivate cannabis indoors even in sub-zero temperatures. Here's a step-by-step guide on how to do it.
In principle, this applies to beginners and seasoned professionals alike: When growing cannabis, there are numerous factors to consider and various methods to achieve successful yields. Most importantly: Don't panic, nobody is born a master, and one of the best parts of growing is observing and learning for the next grow!
Step 1: The right room
Choose a well-insulated room or a dedicated grow box where you can optimally control the conditions. Garages or cold basements are less suitable without additional insulation. Your goal: The temperature should be constant and controllable.
Step 2: Setting up the lighting
Sunlight is scarce in winter, making artificial lighting essential. High-quality LED grow lights or HPS lamps are ideal, as they provide the correct light wavelengths for plant growth. An optimal cycle is 18 hours of light and 6 hours of darkness during the vegetative stage, and 12 hours of light and 12 hours of darkness during the flowering stage.
Step 3: Temperature control
Your plants thrive in temperatures between 20°C and 28°C . Use space heaters or heating mats to maintain this temperature, even in a cold room. Be careful that the temperature doesn't fluctuate too drastically, as this could stunt plant growth. Please note: When growing indoors, it's crucial to avoid safety risks such as overheating and short circuits, especially when using space heaters and heating mats. Ensure you use only high-quality, moisture-resistant devices with overheat protection and that the electrical wiring is correct. Use thermostats to control the temperature, install smoke detectors, and ideally, keep a fire extinguisher readily available. This will minimize the risk of fire and create a safe environment for your growing project.
Step 4: Ventilation and air circulation
Good air circulation prevents mold growth and keeps plants healthy. Therefore, install fans to bring fresh air into the tent and expel warm, stale air. An exhaust system with an activated carbon filter ensures that stale air and odors are efficiently removed.
Step 5: Regulate humidity
Cannabis requires a humidity level of 40-70% during the vegetative stage . During the flowering stage, the humidity should be reduced to 40-50% to prevent mold growth. A humidifier can help if the air is too dry, while a dehumidifier regulates excessive humidity.
Step 6: Choosing the medium – soil or hydroponics?
- Soil: Easier for beginners. High-quality cannabis soil with the right nutrients provides a stable foundation.
- Hydroponics: More efficient, as the plants are supplied directly with water and nutrients. However, this method requires more precise management of nutrient supply.
Step 7: Nutrient supply
In winter, dry air from heating systems can lead to increased water evaporation, which affects nutrient uptake. Make sure you use a balanced nutrient solution for the growth and flowering phases to prevent deficiencies.
Step 8: Timetable and patience
From sowing to harvest, it can take 8 to 14 weeks, depending on the variety . Ensure consistent care throughout this time – regularly check light cycles, temperature, humidity, and nutrients.
- Growth phase (vegetative phase)
During the growth phase, the plant focuses on root and leaf development. This phase typically lasts 4 to 6 weeks, but can vary depending on the variety and growing goals. It is easily recognizable by the vigorous growth of leaves and stems – and the absence of flowers or pre-flowers. The plant develops numerous side shoots to maximize the surface area for flower formation.
- When to initiate the flowering phase?
The transition is achieved by changing the light cycle. During the growth phase, the light cycle is typically 18 hours of light and 6 hours of darkness. To induce flowering, you change the light cycle to 12 hours of light and 12 hours of darkness.
- Identifying feature: When to switch?
An important indicator of when to initiate the flowering stage is the size and growth pattern of your plant. The plant can increase in size by 50-100% during flowering. Therefore, you should ensure that the plant has reached approximately 50% of its desired final size before switching to flowering. Seeing pre-flowers – small flower buds at the nodes (where the leaves grow from the stem) – is a sign that the plant is about to flower.
- Flowering phase
After switching to a 12/12 light cycle, the flowering phase begins. Here, the plants develop visible flowers (also called buds). Growth slows down, and the plant puts its energy into flower production. Trichomes (small resin glands) and fine white hairs (pistils) begin to form.
Step 9: Harvest time
When the flowers are ripe, meaning when about 70-90% of the trichomes are milky to amber in color, it's time to harvest. Cut the plants and hang them in a dark, well-ventilated room to dry slowly.
Here are a few tips that can help you get the densest and most compact buds possible :
- Light intensity : The buds develop more densely when they receive sufficiently intense light during the flowering phase. High-quality LED or HPS lamps with adequate power (approx. 600-1000 watts) can increase bud density. Ensure that the light reaches the entire plant evenly.
- Air circulation : Good air circulation helps the buds become firmer. Install fans to ensure air circulates well around the plants.
- Temperature and humidity : During the flowering phase, the temperature should be between 20-26°C and the humidity between 40-50% . Excessive humidity can cause the buds to remain fluffy and become susceptible to mold.
- Nutrients : Ensure that the plants receive the right flowering nutrients during the flowering phase , especially sufficient phosphorus and potassium , which are crucial for bud development. Use bloom boosters to support flower growth.
- Trimming and lollipopping : During the flowering phase, remove the lower leaves and smaller shoots (lollipopping) so that the plant concentrates its energy on the upper flower clusters. This will make the upper buds firmer and more compact.
- Proper drying : After harvesting, slow drying is crucial. Hang the plants in a dark room with about 50% humidity and let them dry for approximately 7-10 days . Drying too quickly can make the buds fluffy.
But which seeds are right for me?
There are different strains of cannabis, each with different needs. Sativa strains are generally taller and have longer flowering times, while Indica strains are more compact and flower faster. Autoflowering strains flower independently of light cycles and are more resistant to environmental conditions. Feminized seeds do not flower automatically, allowing growers greater control over the yield.
At Marry Jane you'll find no fewer than 20 different seeds to choose from. Click here for 187 Sweedz, the seeds of the 187 Strassenbande, and here for MJ Seeds.
With this step-by-step guide, nothing stands in the way of your successful indoor winter grow! Have fun and good luck – your Marry Jane Team
All statements without guarantee.
Note on language usage:
For the sake of readability, we have chosen not to use gender-inclusive language in our texts. However, all genders are always addressed equally. At Marry Jane, we place great value on inclusion and equality – everyone is welcome, regardless of gender, identity, or origin.
