Friday, March 17, 2017

Do Grow lights really work? And How to choose the Best Light for Indoor Growing?

Do grow lights really work? Yes!!! All plants need the light. But do you know how to choose a grow light for your plant? Now, let us keep it simple.

Mostly, there are High pressure sodium(HPS) lamp, Metal Halide(MH) lamp, LED light on the market.

The wavelength and effect of plants growing light
1. The color temperature and lumen
The color temperature and lumen are seen by human eyes with no effect on the photosynthesis of plants. Yes, you can ignore these two parameters.
2. The influence of spectrum to plants physiology
280 - 315nm -- minimal influence to the shape and physiology
315 - 400nm -- absorb tiny chlorophyll, affect the photoperiodic effect and prevent the stem growing.
400 - 520nm (Blue) -- absorb maximum chlorophyll and carotene and affect most to the photosynthesis. It suits for promoting plant growth.
520 - 610nm -- absorb pigment in low ratio
610 - 720nm (Red) -- absorb chlorophyll in low ratio and significantly affect the photosynthesis and photoperiodic effect. It makes flower and bear fruit well.

*Based on the above theory, plant growing lights are usually full blue, full red or red-blue-combination to cover the wavelength range that photosynthesis needs. Red-blue-combination light appears pink color in visual.

*Now, I think you have knew how to choose a grow light. Let's put it all together.
Spectrum is the most important parameter. Want your plants growing up, choose BLUE LIGHT; Want them flower and fruit, choose RED LIGHT.
The appropriate spectrum proportion of red and blue light is between 5:1 to 10:1, usually 7~8:1. It would be the best to adjust the proportion according to the plants growing period needs if possible.

The difference between HPS, MH and LED lights.
1. Energy
It is directly related to your electric bill. LED light costs about 1/4 energy consumption of HPS and MH lamp. As for the same wattage, LED light can save 30-40% electricity charge compared to HPS and MH lamp.
2. Application
The working temperature of HPS and MH Lights is pretty high that they would burn out the plant if too close as well as significantly affecting the room temperature if too many. So HPS and MH lights are apply for greenhouse, not for multilayer cultivating rack & seedling stage.

The grow light below 50W is suitable to close to plants, should be 20 - 40 inch height to the plant canopy when applied. Such as plant tissue culture, layered planting, floriculture at home, small space soilless culture. By the way it is good response at seedling stage. Light over 50W is used for greenhouse environment. The best distance between light & plant canopy (most plants) is about 100 inch.

Now I think you should have an idea why blue & red LED grow lights are the best seller, and how to choose the right grow light for your indoor growing.