- What do I look for with CFLs as far as wattage, lumens, and kelvin?
- What’s the difference?
- Which CFLs work best for growing marijuana?
- Why do some CFL’S have a higher wattage and lower Kelvin and some a lower wattage and higher kelvin?
- What are the pros & cons of higher Watts & Lower Kelvin vs. low Watts & Higher Kelvin?
Basically, will you explain wattage, lumens, and kelvin with regards to growing marijuana with CFLs?
Wattage measures the amount of power or intensity/strength of the light.
Kelvin measures the color of the light.
They’re completely separate measurements, as I will explain below.
Generally… more wattage = more light = faster growth = bigger yields.
You may also want to look at “lumens” to understand light output. This is another way to measure light output and is often listed on the package of your CFLs.
Each plant should be covered by around 10,000 lumens per plant or even more. So if a bulb gives off 2,500 lumens, you’d need 4 or more of those bulbs per plant for optimal light coverage.
Remember, more light = plant makes more energy = more yields.
Kelvin is a scale which is used to reflect “color temperature” which is a fancy way of expressing the frequency (color) spectrum given off by a particular bulbs.
Vegetative Stage – 5000K / 6500K
Bulbs that are more blue are called “Bright white” or “Daylight” colored and are listed with a Kelvin of 5000K / 6500K. These “high kelvin” bulbs are optimal for vegetative growth.
These CFL bulbs mimic the color temperature of the sun during Spring/Summer.
Flowering Stage – 2700K
Bulbs with a more yellow/red tint are listed as “Soft white” colored with a Kelvin of 2700K. These “low kelvin” bulbs are optimal for the flowering stage.
These CFL bulbs mimic the color temperature of the sun during Fall/Winter.
With Kelvin, remember that all of the colors can be used in all of the stages of marijuana growth, but you’ll get the best results when you match the proper color with the stage of growth your marijuana plants are currently in.