Growing Cannabis at Home in Autumn and Winter: Indoor Setup, Lighting, Costs and the Legal Framework

As the days get shorter, the outdoor season ends for many growers. Adults in Germany who may legally grow cannabis for personal use can carry on indoors. This guide explains what an indoor setup needs in autumn and winter, what to expect in costs and which rules apply. It is general information only, not a growing or consumption recommendation and not legal advice.

The legal framework in Germany

Germany's Consumer Cannabis Act (KCanG) allows adults aged 18 and over to grow cannabis privately. The key points:

• Up to three plants per adult at any one time.
• Up to 50 g of dried cannabis may be kept at home and up to 25 g carried in public.
• Plants and harvest must be protected from access by children, young people and third parties, for example in a lockable room or cabinet.
• Passing on or selling the harvest is prohibited.
• Cultivation is tied to your place of residence.

Cannabis policy in Germany is still under debate. Check the current legal position with an official source before you start. If you rent, take a look at your tenancy agreement and speak to your landlord if in doubt.

Why grow indoors in autumn and winter?

Indoors, you control light, temperature and humidity yourself, so growing no longer depends on weather or season. The heating season does bring its own challenges, though: dry air from radiators and cold windowsills noticeably affect the room climate.

The basic setup

Grow tent or grow box: For one to three plants, a tent with a footprint of roughly 60×60 to 100×100 cm is usually enough. It should be lightproof and have a sturdy pole to carry the fan and filter.

Lighting: Modern LED grow lights are the first choice in winter because they are efficient and give off little waste heat. Look for full-spectrum light and follow the manufacturer's recommended coverage area when choosing the wattage, which is usually more reliable than general rules of thumb.

Extraction and odour filter: An extractor fan with a carbon filter keeps the air fresh and dampens odours. It is also a matter of consideration for your neighbours.

Substrate and pots: Good-quality potting soil or ready-made mixes and fabric pots of about 10 to 15 litres suit beginners. Good drainage matters.

Measuring tools: A thermo-hygrometer, a timer and a pH meter are part of the basic kit.

Light and light cycle

Photoperiod varieties need two phases:

• Vegetative phase: around 18 hours of light, 6 hours of darkness.
• Flowering phase: 12 hours of light, 12 hours of darkness.

Autoflowering varieties flower regardless of the light cycle and are often simpler for beginners, but they usually take less time and produce smaller yields. In Germany, seeds may be obtained from EU countries. Choose reputable suppliers.

Getting the winter climate under control

• Temperature: Around 22 to 26 °C is typical in the vegetative phase, slightly lower in flowering. In winter, a tent in a cold room can cool down too much, especially during the dark period.
• Humidity: Around 60 to 70% for seedlings, later 40 to 50%. Dry heating air may call for a humidifier, while air that is too humid during flowering raises the risk of mould.
• Air circulation: A small fan inside the tent helps prevent mould and pests.
• Location: A room without large temperature swings, not directly beside a window or an outside wall.

What does it cost?

Costs depend heavily on the equipment. As a rough guide for a small setup:

• One-off: Tent, LED light, extraction with filter, pots, measuring tools and accessories together often cost around €250 to €600, depending on quality.
• Ongoing: Soil, nutrients, seeds and above all electricity. A small 100 to 150 watt LED light running 12 to 18 hours a day can cost a few euros a month in electricity, a little more with fan and filter.

These figures are guidelines. Prices and electricity tariffs vary, so calculate with your own numbers.

Common mistakes

• Too much nutrient or water: Yellow or burnt leaf tips are often a sign of overfeeding, drooping leaves a sign of overwatering.
• Mould during flowering: Make sure there is a good climate and air movement, and check the plants regularly.
• Light leaks: During the dark period, light from outside can disrupt the cycle.
• Harvesting too early or drying incorrectly: Drying and curing have a big effect on quality. Both are slow processes, done in a dark, cool place with good air circulation.

FAQ

How many plants may I grow?
Up to three plants per adult at any one time.

May I give away or sell the harvest?
No. Passing on and selling are not permitted under the KCanG.

Do I absolutely need a heater in the tent in winter?
Not necessarily. The heat from the lamp is often enough, but in cold rooms an extra heat source can make sense. What matters is that the temperature does not drop too far, even during the dark period.

How long does a growing cycle take?
Depending on the variety, roughly three to five months from germination to harvest, plus drying and curing.

Conclusion

With a bit of planning, indoor growing is quite manageable in autumn and winter. What matters is a suitable setup, a stable room climate and compliance with the legal requirements, above all protection against access by third parties. Do your research beforehand and, if in doubt, ask an official body.

This article is for general information only. It contains no health claims, no encouragement to consume and no legal advice.