Wie viel Licht benötigt Cannabis zum Wachsen?

How much light does cannabis need to grow?

Light is one of the most crucial factors for the growth and health of cannabis plants. The amount and quality of light affect photosynthesis, growth, flowering and ultimately harvest quality. To get the most out of your cannabis grow, it is important to understand the light needs of the plants and manage them accordingly. Here are the essential aspects of providing light to cannabis plants.

1. Light requirements in the different phases

Cannabis plants require different lighting conditions in the different growth phases:

  • Germination: During the germination phase, which lasts about 1 to 7 days, the young plants only need gentle light. A simple grow light setup or natural sunlight can be sufficient. The light intensity should be low so as not to overwhelm the delicate seedlings.

  • Vegetative phase: During the vegetative phase, which lasts 3 to 8 weeks, cannabis plants require about 18 hours of light and 6 hours of darkness per day. This long period of light promotes the plant's growth by maximizing photosynthesis and allowing the plants to grow into strong, healthy specimens.

  • Flowering phase: To initiate flowering, the photoperiod is reduced to 12 hours of light and 12 hours of darkness per day. This amount of light simulates the natural light conditions of autumn and promotes flower formation. The flowering phase usually lasts 6 to 12 weeks, depending on the variety and growing conditions.

2. Types of light and their meaning

Choosing the right light is crucial to the success of your grow. There are different types of lights, each with different features and benefits:

  • LED lamps: LED lamps are energy efficient and offer a full spectrum that covers all phases of plant growth. They generate little heat and have a long lifespan. High-quality LED lamps are particularly suitable for indoor cultivation.

  • HID (High Intensity Discharge) Lamps: HID lamps, including metal halide (MH) and high-pressure sodium (HPS) lamps, are also very effective. MH lamps are often used in the vegetative stage because they provide a bright, blue light that promotes growth. HPS lamps are ideal for the flowering stage because they emit a warmer, orange-red light that stimulates flower formation.

  • Compact Fluorescent Lamps (CFL): CFL lamps are a cost-effective option to start with, but they don't provide the same light intensity or efficiency as LEDs or HID lamps. They are good for smaller growing spaces or for the germination phase.

3. Light intensity and distance

Light intensity is just as important as the duration of the light. Too little light can slow growth, while too much light can burn the plants.

  • Light intensity: Light intensity is often measured in Par (Photosynthetically Active Radiation). Plants need sufficient light intensity to perform photosynthesis effectively. In general, cannabis plants require a light intensity of around 400 to 600 µmol/m²/s during the vegetative phase and 600 to 1000 µmol/m²/s during the flowering phase.

  • Light distance: The distance between the lights and the plants is important. Lights placed too close can burn the plants, while lights placed too far away can slow growth. For LED lights, the distance should be about 30-60cm in the vegetative phase and 30-45cm in the flowering phase. For HID lights, the distances can be a little larger, about 60-90cm in the vegetative phase and 45-75cm in the flowering phase.

4. Light cycles and control

Controlling the light cycle is crucial to managing the growth and flowering of your plants. Automatic timers can help to precisely maintain light cycles and ensure your plants receive consistent conditions.

  • Automatic timers: Timers can be set to reliably turn the lights on and off at set times. This is especially important for indoor growing where precise light cycles are required.

5. Conclusion

Cannabis plants require careful light provision to grow healthily and produce a high quality harvest. During the germination phase, gentle light is sufficient, while the vegetative phase requires about 18 hours of light per day. The flowering phase begins with a reduction to 12 hours of light and 12 hours of darkness. Choosing the right type of grow light, the right light intensity and the distance between the light source and the plant are crucial for the success of the cultivation. With the right light provision, you can optimize the growth of your plants and enjoy a bountiful harvest.

6. Choosing the right variety

The most important thing when growing cannabis plants at home is choosing the right strain. It should suit your growing conditions and meet your preferences in terms of taste and effect.

Here are the best cannabis strains that you will also like:

  • Northern Lights: This strain is the most legendary cannabis strain there is! Perfect for beginners and a classic among the strains with a stimulating, alert effect.
  • Green Gelato: What a delicious effect! This strain produces a large yield and leaves you feeling alert and refreshed, while providing euphoria and creativity - a delight.
  • OG Kush: A classic for experts! The variety is feminized and therefore perfect for you if you grow in controlled conditions such as a grow tent. The effect is relaxing and calming.
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