To know which type of grow light will be best for your microgreens, you need to understand a few technical things about light and what the plant needs in terms of lighting for photosynthesis.
PAR value for Microgreens
PPFD (photosynthetic photon flux density) is a measuring unit of PAR (Photosynthetic Active Radiation), which is a spectrum or range of colors of light from 400 to 700 nanometers that plants are able to use for photosynthesis. For microgreens, the light should be full spectrum with a high PAR value (400-700nm).
Light intensity for Microgreens
Microgreens require high intensity light (like sunlight) to grow at their best with the best crunch and flavor development.
Lumen tells us how bright a light source is. Higher the value, brighter the light will be. Lux is the total amount of light that falls on a surface. The closer the light is to the seed tray, the higher the Lux reading. For microgreens, the grow lights should have 1600 to 2000 Lumens of brightness so it can cast the light from the recommended hanging distance from the plants.
Color Temperature for Microgreens
Color temperature is used to describe the appearance provided by a light, how it will look when you turn the light On. The value ranges from 1000 Kelvin to 10,000 Kelvin. It is a spectrum of warm colors to cool colors:
- warm white (2000-3000K)
- bright/cool white (3100-4500k)
- daylight (4600-6500K).
The color temperature of sunrise/sunset is 3200K, natural daylight is 5500 K and the blue sky is 12000K. For microgreens, the color temperature of the light should mimic daylight, i.e. a minimum of 4000K to 6500k, just like the color temperature of daylight.
T8 fluorescent lights are one of the ideal choices for growing the best quality microgreens indoors. You can also use T8 LEDs or simply place them near a sunny location that receives abundant sunlight.
A recommended product that matches this specification is JESLED T8 LED grow lights. They have a color temperature of 6000K with 3000+ lumens. They work great with microgreens and are a very cost effective light setup for microgreens. It will cost just $10 a piece and it will cost you about $0.55 to run 3 lights for 17 hours/day for 7 days. As you go along, you can invest in a 300w full spectrum LED which costs about $70 a piece.
About T8 Fluorescent Lights
Fluorescent lights produce short-wave ultraviolet light. They are cost-effective, have good light intensity, and the heat produced is not much so it does not harm the young seedlings.
T8 is a tubular light with a diameter of 1 inch. T5 is 0.6".
- Do not leave the light open all day as the leaves can wilt or burn.
- Keep the spacing between your grow lights and top of your tray no more than 6".
- Not getting enough light for even 1 day can weaken your microgreens.
- Microgreens that get less light become pale. On the contrary, microgreens could burn with too much light.
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