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.
They’re completely separate measurements, as I will explain below.
Kelvin measures the color of the light.
Wattage measures the amount of power or intensity/strength of the light.
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.
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.
Vegetative Stage – 5000K / 6500K
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? Basically, will you explain wattage, lumens, and kelvin
The variety of grow lights available today can be confusing, especially for those new to cannabis cultivation. We look at the different types of lighting along with their pros and cons.
Cannabis cultivators know how important light is when it comes to growing successfully. A sufficient amount of the right type of light is one of the most crucial factors for healthy growth and yields of potent buds.
Their availability and low cost are among the advantages of CFL grow lights. These bulbs have standard sockets so you can use them with any standard light fixture. Commonly used CFLs for growing cannabis range from 40W and upwards. They are available in various colour temperatures such as “daylight” at 6500K or “warm white” with a more reddish light spectrum at 2700K. Bulbs with a “daylight” spectrum are more suitable for the vegetative growth phase while “warmer” CFLs with their more reddish light are better for the flowering of your plants.
You can find various types of grow lights for indoor cultivation today. However, not all types of grow lighting are equal. There can be big differences when it comes to their effectiveness and costs. Let’s look at the available grow lighting types together with their pros and cons.
Most advanced growers, therefore, use a combination of MH/HPS bulbs for the duration of their grow. If for some reason you need to choose one type of HID for the entire grow you should get an HPS light.
HID lights cannot just plugged-in to a regular light socket because they need a special hood and ballast. As such, they are extremely power hungry, and can significantly increase electricity bills.
Powerful HID lights in the 600W range or more can produce big amounts of heat. This means you will need adequate exhausts and vents in your grow room. Also, because HID bulbs degrade over time, their life span is somewhat limited. You will have to replace your bulbs periodically. Some growers get new bulbs every year while others grow with them a little longer.
The light output of CFL bulbs is low compared to other types of grow lighting. You will have to put the CFL bulbs very close to your plants if you want to provide them sufficient light. Unless you are willing to use a number of CFL bulbs, CFLs are normally better suited for smaller grows, say if you only grow one or two plants. On the other hand, “day light” CFL grow lights can be the ideal grow lights for clones and seedlings.
There are two main types of HID lights, MH (Metal Halide) lights and HPS (High Pressure Sodium) lights. The difference between the two is that MH lights give a “cooler”, blueish light whereas HPS lights sit at the red end of the spectrum. This makes MH lights better suitable for the vegetative phase of your plants and HPS better for flowering.
We compare lights suitable indoor cannabis cultivation, with their pros and cons. What lighting solution is best?