Light is essential for photosynthesis, the process by which plants convert light energy into chemical energy. This energy is stored in the form of glucose, which is essential for plant growth and development. Without sufficient light, photosynthesis cannot take place efficiently, resulting in stunted growth and lower yields.

Effects of too little light

Too little light can have serious effects on cannabis plants:

Weak growth: Plants that do not receive enough light grow more slowly and develop thin, weak stems.
Elongated internodes: The spaces between the leaves become larger, resulting in a sparse appearance.
Less Flowers: The production of Flowers is greatly reduced, which leads to lower yields.
Chlorose: A lack of light can cause the leaves to turn yellow as the plant does not have enough energy to produce chlorophyll.

Effects of too much light

Too much light can also be problematic:

Lichtstress: Plants that are exposed to too much light can show symptoms of light stress, such as burnt leaves and discolouration.
Hitzestress: Excessive lighting can lead to overheating of the growing area, which further weakens the plants and increases the risk of disease.
Reduced photosynthesis: Excessively intense light can increase the photosynthesis rate beyond the optimum level, which leads to the formation of reactive oxygen species that can damage the plant cells.

To obtain healthy and productive cannabis plants, it is therefore important to find the right balance and avoid both too little and too much light.

Which light for cannabis plants?

LED-Lampen

Advantages of LED lamps

Energieeffizienz: LEDs consume less power compared to other types of lamps, which reduces electricity costs.
Low heat generation: LEDs generate little heat, which reduces the risk of heat stress and enables better temperature control.
Long service life: LED lamps have a long service life, which makes them a cost-effective option.
Full light spectrum: Modern LEDs offer a broad light spectrum that imitates natural sunlight and optimally supports plants in all growth phases.

Application and care

Installation: Make sure that the lamps are evenly distributed over the cultivation area to ensure uniform lighting.
Distance to the plant: Keep a sufficient distance between the LED lamps and the plants to avoid light stress. A distance of 30-60 cm is usually sufficient.
Wartung: LEDs require little maintenance, but make sure to clean the lamps regularly to remove dust and dirt that could affect the light intensity.

Fluorescent lamps (CFL)

Advantages of CFL lamps

Kostengünstig: CFLs are cheaper to buy than other types of lamps.
Easy handling: They are easy to install and use, making them ideal for beginners.
Low heat generation: CFLs also generate little heat, which minimises the risk of heat stress.

Application and care

Installation: CFL lamps should be placed close to the plants, usually about 5-10 cm away, to ensure optimum light intensity.
Lichtzyklen: CFLs are well suited for the vegetative phase and should provide around 18 hours of light per day.
Wartung: Replace the lamps regularly as they lose intensity over time. Make sure to keep the lamps clean to ensure maximum efficiency.

Metal halide lamps (MH)

Advantages of MH lamps

High light intensity: MH lamps provide a strong light intensity that is ideal for the vegetative growth phase.
Promotes growth: The blue spectrum of MH lamps promotes dense, bushy plant growth.

Application and care

Installation: Place the lamps at a distance of around 30-50 cm from the plants to ensure optimum light intensity.
Belüftung: Make sure that the growing space is well ventilated to compensate for the additional heat emitted by the MH lamps.
Wartung: MH lamps have a shorter service life than LEDs and should be checked and replaced regularly to ensure constant light intensity.

High-pressure sodium vapour lamps (HPS)

Advantages of HPS lamps

Ideal spectrum for the flowering phase: HPS lamps produce a yellow-red spectrum that promotes flower formation and increases the yield.
High light intensity: They provide strong light intensity, which is ideal for the flowering phase.

Application and care

Installation: Keep a distance of about 50-70 cm between the HPS lamps and the plants to avoid burns.
Belüftung: As HPS lamps generate a lot of heat, good ventilation and cooling of the growing space is necessary.
Wartung: HPS lamps have a limited service life and should be replaced regularly to ensure consistent light intensity.

Light stress: cannabis too much light

Symptoms of light stress

Burnt leaves

One of the most common signs of too much light is burning of the leaves. The leaf edges and tips can turn brown and dry. This occurs when the plants are too close to the light source or receive too intense light.

Verfärbungen

Light stress can also lead to discolouration of the leaves. The leaves often appear yellowish or whitish as the chlorophyll is damaged by excessive light. This can impair photosynthesis and slow down plant growth.

Measures against light stress

Correct distance to the light source

To avoid light stress, it is important to maintain the correct distance between the plants and the light source. The distance should vary depending on the type of lighting:

LED-Lampen: 30-60 cm
CFL-Lampen: 5-10 cm
MH-Lampen: 30-50 cm
HPS-Lampen: 50-70 cm

Compliance with the light cycles

Make sure you maintain the correct light cycles for each growth phase:

Keimlinge: 18-24 hours of light per day
Vegetative phase: 18 hours of light and 6 hours of darkness
Blütephase: 12 hours of light and 12 hours of darkness

Adhering to these light cycles helps to minimise light stress and optimise plant growth.

Ventilation and cooling

As too much light often leads to overheating, good ventilation and cooling of the growing space is crucial. Here are some tips:

Luftzirkulation: Use fans to distribute the air evenly in the room.
Abluftsysteme: Install an exhaust air system to dissipate excess heat.
Klimatisierung: In extremely hot environments, the use of air conditioning may be necessary to control the temperature.

With proper care and monitoring, you can ensure that your cannabis plants receive the optimal amount of light and grow healthily.

Avoid light stress with our high-quality grow boxes

Light stress can significantly affect the growth and yield of your cannabis plants. With our specially developed grow boxes, you can create optimal growing conditions and effectively avoid light stress. Our grow boxes offer:

- Ideal lighting conditions: Our grow boxes are equipped with high-quality, dimmable LED lighting systems that guarantee optimum light intensity for every growth phase.

- Perfect light cycles: Integrated timers ensure constant light/dark cycles that support the natural rhythm of your plants.

- Easy handling: Our grow boxes are user-friendly and allow you to easily adjust the lighting and ventilation so that your plants always have the best conditions.

Our top grow boxes

Growbox Cultibox Light Plus 60 (60x60x140)

Compact size, ideal for small cultivation areas. Perfect for beginners.

Growbox Cultibox SG-Combi 60 (60x60x140 cm)

Flexible design, easily expandable. Suitable for versatile mounting options.

Cultivation box Cultibox SG-Kombi 80 (80x80x160)

Larger cultivation area for medium-sized projects. Robust and durable construction.

Grow box cultivation box Cultibox SG-Kombi 100 (100x100x200)

Ideal for larger cultivation projects. Offers plenty of space for a variety of plants.

Growbox Blackbox Silver 100x100x200

Highly reflective inner coating for maximum light yield. Ideal for experienced growers.

Growbox Dutch Masters Eco 150 (150x150x220 cm)

Extra large grow box for professional growers. Excellent ventilation options and robust design.

Say goodbye to light stress and increase the quality and quantity of your harvest. Besuche our growbox collection and find the perfect grow box for your needs.

Cannabis cuttings light

Light requirements for cuttings

Lichtintensität

Cuttings require moderate light intensity to form roots and grow without being stressed. Excessive light intensity can burn the tender cuttings and impair their growth. Use low to medium intensity lighting, such as CFL or LED lamps specifically designed for growing cuttings.

Duration of lighting

Ideally, cuttings should receive 18-24 hours of light per day. Continuous lighting helps to promote growth and accelerate root formation. However, make sure that the light source is not too intense to avoid overheating and dehydration.

Optimal conditions for cuttings

Temperature and humidity

In addition to the right lighting, temperature and humidity are crucial for the successful growth of cuttings:

Temperatur: Keep the temperature in the growing room constant between 20-25 °C. Temperatures that are too high or too low can impair growth and make the cuttings susceptible to diseases.
Feuchtigkeit: Cuttings require a high humidity of around 70-80% to minimise water loss through the leaves. Use a dome cover or mini-greenhouse to maintain the humidity.

Distance to the light source

The distance between the cuttings and the light source should be chosen so that the plants receive sufficient light without being burnt. Here are some guidelines for the distance:

LED-Lampen: 30-45 cm
CFL-Lampen: 10-15 cm

It is important to check and adjust the spacing regularly as the cuttings grow and their needs change. Placing them too close can lead to burns, while placing them too far apart can slow down growth.

Cannabis growth phase light

Light requirements in the vegetative phase

Light duration and intensity

In the vegetative phase, cannabis plants need a lot of light to grow strong and healthy. The ideal light duration is around 18 hours of light and 6 hours of darkness per day. High light intensity is also important to promote dense foliage and strong stems. Make sure that the plants are evenly lit to ensure uniform growth.

Optimum lamp types

The following lamp types are particularly suitable for the vegetative phase:

LED-Lampen: Offer a broad light spectrum and are energy-efficient. They promote growth thanks to their intense blue light, which is ideal for the vegetative phase.
Metal halide lamps (MH): Produce a strong blue-white light that supports vegetative growth. They are particularly suitable for larger cultivation areas as they provide high light intensity.

Light requirements in the flowering phase

Light duration and intensity

During the flowering phase, the light requirements of cannabis plants change considerably. The light duration is reduced to 12 hours of light and 12 hours of darkness per day to promote flower formation. The light intensity remains high, but the light spectrum should contain more red-orange components to support Flower.

Optimum lamp types

The following lamp types are ideal for the flowering phase:

LED-Lampen: Many modern LED lamps are designed to cover the entire light spectrum, including the red components that are important for the flowering phase. They remain energy efficient and generate less heat.
Hochdruck-Natriumdampflampen (HPS): Produce a yellow-red spectrum that is ideal for the flowering phase. HPS lamps promote flower formation and increase the yield. They are particularly suitable for experienced growers aiming for large harvests.

Cannabis seedlings light

Light requirements for seedlings

Lichtintensität

Cannabis seedlings require moderate light intensity to grow healthily. Too strong light can burn the tender seedlings, while too weak light slows growth and produces weak, spindly plants. A light intensity of around 100-300 µmol/m²/s is ideal for seedlings.

To achieve this light intensity, LED or CFL lamps are the best options. LEDs are particularly suitable as they offer a broad spectrum of light wavelengths and are also energy efficient. CFL lamps are a cost-effective alternative that also work well. It is important to place the light source close to the seedlings, but care should be taken to ensure that the distance is not too small to avoid burns.

Duration of lighting

Seedlings should receive 18-24 hours of light per day to promote rapid and healthy growth. This continuous lighting helps the young plants to develop strong roots and a robust structure. A continuous lighting cycle ensures that the seedlings receive enough energy for their development, which is particularly important in the first few weeks after germination.

The lighting duration can be adjusted according to personal preference and the specific requirements of the plant variety. Some growers prefer 24-hour lighting to maximise growth, while others use an 18/6 cycle (18 hours of light, 6 hours of darkness) to better mimic the natural daily cycle and give the plants a rest period.

Common mistakes and how to avoid them

Too little light

One of the most common mistakes when growing cannabis seedlings is providing too little light. This causes the seedlings to become elongated, thin and weak. These weak plants are less resilient and more susceptible to diseases and pests.

To avoid too little light:

Placement of the lamps: Make sure that the light source is close to the seedlings, but not too close to prevent burns. For LED lamps the distance should be about 30-45 cm, for CFL lamps about 10-15 cm.
Light intensity control: Use a luxmeter or PAR meter to monitor the light intensity and ensure it is within the recommended range. If the light intensity is not sufficient, add additional light sources to ensure even lighting.

Too much light

Too much light can be just as harmful as too little. Excessive light can burn the seedlings, bleach their leaves and stunt their growth. This leads to stress and poorer plant development.

To avoid too much light:

Distance to the light source: Keep a sufficient distance between the lamps and the seedlings. Take care not to bring the lamps too close to the plants to avoid burns.
Beleuchtungsdauer: Make sure that the lighting period does not exceed 24 hours per day. A short period of darkness can help the seedlings to recover and reduce stress. An 18/6 light cycle can be particularly beneficial here, as it provides a balance between light supply and rest period.

By avoiding these common mistakes and ensuring the right light conditions for your cannabis seedlings, you lay the foundation for healthy, vigorous plants and a successful harvest.

Cannabis too little light

Signs of a lack of light

Weak plant growth

A clear sign of light deficiency in cannabis plants is weak, spindly growth. Plants that do not receive enough light will desperately stretch towards the light source, resulting in longer internodes (the spaces between the leaves). These plants often appear long and thin, have weak stems and are unable to support the weight of Flowers or dense foliage. This elongated growth is a natural attempt by the plant to get closer to the light source in order to obtain more energy for photosynthesis.

Discoloured leaves

Another clear sign of a lack of light is the discolouration of the leaves. Plants suffering from a lack of light can develop yellow or pale leaves as they do not receive enough light to produce sufficient chlorophyll. Chlorophyll is necessary for photosynthesis and gives the leaves their green colour. A lack of it leads to chlorosis, a yellowing of the leaves that is often first visible on the older, lower leaves. This is an indicator that the plant is not able to produce enough energy for its growth and development.

Measures in the event of a lack of light

Increasing the light intensity

To remedy the lack of light, it is necessary to increase the light intensity. This can be achieved by the following measures:

Additional light sources: Add more lamps to increase the light intensity. LED lamps are particularly efficient and can provide the required light spectrum to promote growth.
Reflektoren: Use reflective materials such as Mylar or white walls to distribute the light evenly and maximise lighting efficiency. Reflectors help to direct the light onto the plants instead of wasting it.
Optimal placement: Ensure that the lamps are evenly distributed over the growing area to avoid shaded areas. Regularly check the distance between the plants and the light sources to ensure that all areas are sufficiently illuminated.

Optimisation of the lighting duration

In addition to increasing the light intensity, it is also important to optimise the lighting duration:

Lichtzyklen: Ensure that the plants receive 18 hours of light and 6 hours of darkness during the vegetative phase. In the flowering phase, the light cycle should be switched to 12 hours of light and 12 hours of darkness.
Use timer: Use timers to precisely control the lighting duration and ensure that the plants receive regular and even light phases.
Monitoring and customisation: Observe the plants regularly and adjust the lighting duration if necessary. Different varieties and growth stages can have different light requirements, so it is important to remain flexible and adjust the conditions accordingly.

By increasing the light intensity and optimising the lighting duration, you can ensure that your cannabis plants receive enough light to grow healthily and produce high yields. Make sure to regularly check and adjust the conditions to ensure optimal growing conditions.

Fazit

The right lighting is crucial for the successful cultivation of cannabis. A lack of light can lead to weak growth and discoloured leaves, while optimal light intensity and duration promote healthy growth and flower formation. The most important points are summarised here:

Light intensity and duration : Seedlings and cuttings require moderate light intensity and long lighting periods, while adult plants require specific light cycles in the vegetative and flowering phase.
Signs of lighting problems :
- Too little light : Weak, elongated growth and yellow leaves.
- Too much light Burnt and discoloured leaves, signs of light stress.
Measures for lighting problems :
- Remedy lack of light Increase the light intensity with additional light sources and reflectors and optimise the lighting duration.
- Avoiding light stress : Correct distance from the light source and compliance with the optimum light cycles.
Optimal conditions Use LED or CFL lamps for seedlings and cuttings and regularly adjust the distance and duration of lighting to provide the plants with the best growing conditions.

By taking these factors into account, you can optimise the lighting conditions for your cannabis plants and grow healthy, high-yielding plants. Make sure to regularly check and adjust the lighting conditions to always provide the plants with the best conditions.

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Fachautor und Biochemier Niklas Bergmann

Niklas Bergmann, Fachautor

Freut euch auf die Insights von unserem Biochemiker Niklas Bergmann! Mit seinem tiefen Verständnis für alles, was mit Hanf zu tun hat, liefert er euch die neuesten und coolsten Infos direkt in euer Feed. Schnörkellos und klar verpackt er das komplexe Thema Cannabinoide und macht es für euch easy zugänglich. Mit Niklas an der Spitze unseres Wissens-Teams seid ihr immer top informiert.