Plant lighting - facts and tips about growth lights and plant lights

• LED plant lamps:
  Most plant lamps are now equipped with LED lamps (Light Emitting Diode) that have a long lifespan and use little electricity. LED lamps use 80–90 percent less energy than a regular light bulb or halogen lamp. The new LED fixtures are often slightly slimmer in shape and take up less space than others.
• Quality of light:
  In the world of lighting, there are many terms to describe the quality of light. Natural daylight contains all the colors of the rainbow and is therefore called full spectrum light. This is the type of light plants need. You will also encounter many more words that describe the light of the lamps:
• Important light measurements:
  • Watt measures power, for example, 60 W
  • Kelvin degrees measure color temperature, for example, 4000 K
  • Lux is a measure of light intensity, which is how much light hits a specific surface.
  • Lumen measures how much light a light source emits, for example, 2200 lm. If a light source of 100 lumens shines on one square meter, the brightness on that surface will be 100 lux.
  • Micromole measures brightness per second and square meter, for example, 200 µmol/s/sqm.
• Lumens and lux vs. micromoles:
  Apart from watts, lumens and lux may be the most well-known terms, but they are not actually so useful when it comes to growing plants. Lumens and lux describe how our eyes perceive light.
• Micromoles for plant growth:
  When growing plants, we therefore talk about micromoles instead. This term describes the number of light particles emitted from a lamp and hitting a surface. A basic rule among professional producers is that it takes about 200 micromoles per second and square meter for seed sowing.
• Watts and micromoles:
  If you have a lamp of 100 watts, the brightness on a square meter will be about 200 micromoles. A good benchmark is therefore 100 watts per square meter. The lamp should be on for 16 hours to achieve the best growth for the plant.
• Supplemental lighting for indoor plants:
  If the lamp is used as supplemental lighting for indoor plants or for plants that will overwinter in a cool room, less light is needed.

In today's market, there is a wide range of different plant lighting available. You can also use cheap low energy lamps with a simple screen or a fluorescent tube with white light. They are both options that provide a lot of light for the money.

For white color shades, there is a rough division into warm white, neutral white, and daylight white. All white variants work well, as they contain all colors. The only lighting that cannot be used is regular light bulbs. They are inefficient, emit too much heat, and do not contain the type of light that plants need.

Fluorescent fixtures are available in many different lengths. They usually have a cool, blue-white light. If you want a warmer and more comfortable light, you can choose a fluorescent tube with 4000 kelvin. The higher the number, the colder the light is perceived.

The distance to the plants should ideally be around 10-20 cm. As the plants grow taller, gradually raise the lighting to a distance of 50 cm. If you use LED lighting, it is possible to have it closer to the plants without causing burns. LED lights emit less heat.

Tips! Regardless of the type of lighting you choose, it is wise to choose a variant that can be raised and lowered!

• Light for sowing seeds:
  What is most light-demanding is to sow seeds and pre-cultivate vegetables, herbs, and flowers for planting. They need at least 200 micromoles or 100 watts per square meter. The lighting should be on for 14 to 16 hours per day. Follow the circadian rhythm and turn off the light at night.
• Light for indoor plants:
  If your indoor plants are a bit inside the room, they normally do not receive enough light in winter and therefore need supplemental light from a lamp. They need about 100 micromoles or 50 watts per square meter, for 12 to 14 hours per day. Follow the circadian rhythm and turn off the light at night.
• Light for overwintering plants:
  If you have plants that need to overwinter, it is best to store them in a cool place, such as a cellar. They need about 70 micromoles or 30 watts per square meter from 8 to 12 hours per day.
• Tip:
  Feel free to use a timer so you don't have to remember to turn the light on and off.
• Source:
  Bergstrand, Karl-Johan. 2015. Modern plant lighting.