The Right Light Spectrum for Cannabis Plants: A Guide to Optimal Yields
The right lighting is a crucial factor for success in cannabis cultivation. The light spectrum plays a central role as it directly influences the growth and development of the plants. In this blog post we explain what a light spectrum is, which colors are important for cannabis plants and how to optimally adapt the lighting to the different growth phases.
What is the light spectrum?
The light spectrum describes the wavelengths of visible and invisible light emitted by a light source. It is measured in nanometers (nm) and ranges from ultraviolet (UV) light to infrared (IR) light. Each wavelength affects plants in a different way.
- Blue light (400-500 nm): Promotes the vegetative phase by stimulating photosynthesis and producing compact plants with stronger stems and leaves.
- Red light (600–700 nm): Supports the flowering phase and increases the formation of flowers and fruits.
- Far Red (700–800 nm): Affects plant elongation and plays a role in controlling the plant growth cycle.
- UV light: Can increase the production of cannabinoids and terpenes, but should be used carefully so as not to damage the plants.
The optimal light spectrum for different growth phases
1. Seedling and vegetative phase
During this phase, the focus is on developing strong roots, stems and leaves.
- Blue light is particularly important because it promotes compact growth and prevents plants from shooting up.
- Recommended wavelengths: 400–450 nm .
LED lamps with a high proportion of blue light or full-spectrum lamps are ideal here.
2nd flowering phase
During the flowering phase, cannabis plants need more red light to develop large and dense flowers.
- Red light supports photosynthesis and stimulates flower formation.
- A small amount of blue light ensures stability and quality.
- Recommended wavelengths: 620–660 nm .
Modern LED panels allow the spectrum to be individually adjusted to the phase, which offers maximum control.
3. Late phase of flowering
In the final phase, additional UV light sources can be used to increase resin and terpene production. However, UV light can stress the plant, so careful dosing is important.
Lighting Types for Cannabis Cultivation
1. LED lamps
LED lights are energy efficient and offer a wide, adjustable spectrum, making them ideal for growers who want maximum control over their lighting.
2. HID lamps (MH and HPS)
- Metal halide lamps (MH): Good for the vegetative phase due to their high proportion of blue light.
- High-pressure sodium lamps (HPS): Excellent for the flowering phase thanks to their red light spectrum.
3. Full-spectrum lamps
These lamps cover the full spectrum and are an excellent choice for all growth phases. They are especially practical for smaller grow rooms.
Tips for the right lighting
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Lighting duration:
- Vegetative phase: 18–20 hours of light per day.
- Flowering phase: 12 hours of light and 12 hours of darkness.
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Light intensity:
- Too much light can stress plants, while too little light inhibits growth. Regularly adjusting the light source to the size of the plant is crucial.
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Quality of the lamps:
- Invest in high-quality lamps that provide uniform illumination and optimally cover the spectrum.
Conclusion
The right light spectrum is a key to successful cannabis cultivation. By adapting the lighting to the respective growth phase, yields can be maximized and the quality of the harvest improved. LED technology offers the best options here as it is efficient, flexible and sustainable. With the right knowledge and the right equipment, nothing stands in the way of a successful harvest!