Calculating your grow lighting requirements really is just two steps - determine your plant’s lighting needs (watts/square foot), and your plant canopy dimensions.
A common mistake new growers make is measuring the dimensions of the
grow room itself.
What you really should be measuring is the footprint of your
plant canopy.
For example, if you are growing in a 5’ x 5’ space but your plant canopy only takes up 4’ x 4’, you don’t need a grow light capable of lighting the 5’ x 5’ space - it would be overkill.
Cannabis plants grow best with 20-30 watts of light per square foot. Don’t make the mistake of thinking more is better. Too much light can lead to bleaching and burning your plants.
Let's say you are growing in a
5’ x 5’ grow space. If your plants need 20-30 watts/square foot, and your canopy takes up 4’ x 4’ of that space, you will need
320-480 watts of grow lighting.
I might think of going LED it could save you a bit on electric and give the plants a better spectrum of lighting.
If you are planning on using
LED grow lights, there are a few things you need to know about calculating your grow light coverage.
Some manufacturers have two different wattage specifications - displayed wattage and actual wattage (power draw).
Because LED grow lights operate so efficiently, manufacturers will display a wattage equivalent to HPS. For example, the
Gavita LED 1700e is 646
actual watts, but is equivalent to a 1,000 watt HPS.
So, if your 5’ x 5’ growing space requires 320-480 watts of grow lighting, and you choose the LED route, make sure your LED light features an
actual wattage of between 320-480.
Now that you know how many total watts of grow lighting you need, you can decide how many lights you will use.
Our
grow light setup post will help you with this step, as there are plenty of possibilities.
With this 5’ x 5’ grow example, the space is big enough where two grow lights could be an option.
However, it would make more sense to use one large grow light.
The number of grow lights your room will need really depends on the size of it.
Grow lights have gotten more and more powerful as technology continues to advance, but at a certain point, 2 lights can cover an area more effectively than 1.
There are also grow rooms that will need even more lights. For example, an
8’ x 8’ grow room would likely need 4 grow lights, and a
10’ x 20’ room could need up to 8 lights.
Related Products
Courtesy of Hydrobuilder..