CFL Grow Light Upgrade Guide

by Nebula Haze

Growing cannabis with CFL grow lights? Got a very short grow space?

CFLs are one of the only choices for growers with a very short, tiny grow space. If you have at least 2 feet of length and width, CFLs might not not be the best choice for you. Learn more about the strengths and weaknesses for different types of grow lights.

If you’ve got less than 250W of CFLs (CFLs are perfect if you’re growing in a very short space) you can upgrade your CFL grow (without changing the electricity bill) by getting more bulbs. Let me explain…

Watt for Watt…
Small CFL Bulbs > Big CFL Bulbs

Growing Cannabis with CFLs – What Growers Need to Know

With CFLs, more small bulbs will work better than fewer big bulbs. So if you have some big CFL bulbs, a great way to upgrade is to get the same total wattage with smaller bulbs.

The light from CFLs is only “good” for the plant at short distances (under 10 inches), so to maximize your CFL grow, you want to get even light coverage over the entire surface of your plant. Basically you want the entire plant bathed in light with no dark or shadowy spots. This can only happen with many CFL bulbs, since each individual bulb has a limited range.

Picture of my first grow with CFLs

Example: Let’s say you already have 2 x 100W CFLs (a total of 200W). In this case, you can upgrade by switching to 9 x 23W CFLs (a total of 207W). You can improve your yields this way significantly, and it won’t make a noticeable difference on your electric bill.

Remember that you need to get a light socket to plug in each bulb! In the above example, you would need to get seven extra light sockets (since you already have two for the first two bulbs). With nine points of light instead of just two, you will be able to more evenly cover all the parts of your plant with light.

Once you’ve got 250W (or more) of CFLs, most growers will want to upgrade to a more efficient type of light as opposed to adding more CFLs. The only reason you should stick with CFLs at this point is if you have a very short grow space, and can’t accommodate the bigger height required by more powerful grow lights.


For example, if you have 250W worth of CFLs, you will dramatically increase your yields by switching to a 250W (or bigger) HPS. If you keep the same total number of watts, an HID will not give off any more heat than the setup you have now, but will come with additional cooling options. Learn more about CFLs vs MH/HPS grow lights.



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$300 CFL Grow Light Tutorial

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