Using CFL Lights to Grow Weed? Here’s Why You Might Not Want To!

cfl lights to grow weedWe all love our energy-saving light-givers, don’t we?

Well…all isn’t peaches and gold in a sky of milk and honey.

Using CFL lights to grow weed does have disadvantages, as everything else does in existence; along with the advantages.

How those “disadvantages” or limitations, if you will, affect you and your grow, all depends on how dedicated you are and your close attention to detail will yield miracles.  So what are some disadvantages to keep in mind when using CFL lights to grow weed?


1.) CFL bulbs are only considered “efficient” when growing up to several small or medium-sized plants.

It’s a waste of energy to try and grow a large number of plants or large plants–a HID would prove more suitable. Why is a CFL less efficient than an HID? Well, you would need to compare a group of CFLs, with enough lumens to illuminate all of your plants thoroughly.

For a small space, a HID setup can easily be overkill and provide far too much heat, use too much energy, for plants that need to be far away from the bulb to prevent burning = lost lumens. A CFL is more efficient in this case. For LARGE grow spaces, or grow spaces that accommodate significantly more than 4-5 plants, or plants that are very tall–too tall for CFL coverage–HID lights are the way to grow.

You would have to use so many CFL bulbs, that you would probably meet or exceed the same amount of wattage as a 600 or 1,000 watt HID when it’s all said and done. THAT is defeating the point of using CFLs in the first place–to save power
and money. NOT efficient.


2.) CFLs must be used in groups for best results.

Using a large number of bulbs becomes a problem with mounting and positioning, while simultaneously controlling light reflection and containing heat. If you buy a CFL hood that dissipates heat properly, doesn’t get too hot and reflects light correctly, you shouldn’t be concerned with this issue, since you are most likely using one large bulb per reflector/hood.

However, if you are a DIYer and thus need to create your own reflector, make sure the bulbs are placed in a BUNDLE, as close TOGETHER as possible. Do NOT spread the bulbs out over a large surface area! This effectively diminishes the INTENSITY of usable light shining down, especially considering the typical light footprint below the hood, and around the plants.

This is why it’s best to grow several plants, between 1 and 4 total, to ensure the max amount of light is shining down in as small of a square area as possible, while being as close as possible. Screw COVERAGE, go for INTENSITY!!


3.) CFL bulbs do not have a long “footprint” and must be placed very close to the plant.

CFLs must be place within 1-2 inches, but no more than 4 inches for best results. Plants must be “trained” to utilize compact floro lighting effectively. The term “footprint” is now mutually   interchangeable for “lumens,” so one bulb will not have enough lumens to travel very far without “losing” considerable lumens along the way; this term should not be confused with “penetration.” All light penetrates equally, it’s the AMOUNT of light which determines “penetration!”

Now, unless you plant on using a LOT of CFL bulbs, don’t expect to get very bright light penetrating all of the dense foliage in your garden, unless you are using a reflector that holds a ton of bulbs, and you have trained your plants to receive that light–your fan leaves aren’t unnecessarily blocking other fan leaves from receiving light.

Since you MUST keep the bulbs close to the plant to encourage soaking up all the available lumens, you MUST watch the “burn factor.” You can have the closest leaf to the light at 2 inches away one day, and then the next morning you’ll find that same leaf (or worse, BUD) touching the light…..BURNED. Watch your lights and pay attention daily. Raise them up, or lower your plants–but don’t let ’em burn!


4.) The lumen per watt ratio is much less (50%+) than the ratio of HID lighting such as HPS.

For example, a 23 watt CFL averages roughly 1,600 lumens, giving it a lumen per watt ratio of 69.6. On the other hand, a 600 watt HPS at 90,000 lumens, runs at a lumen to watt ratio of 150. 150 lumens per watt is DOUBLE that of the CFL at 69.6.

If you are looking for max efficiency for large grows, look elsewhere than energy-saving light because it won’t fit the bill; but you probably already knew that. On the other hand, if you want to maximize results while not busting the budget, and you want a small-scale personal grow, look no further than CFL lighting. At a range of 60-70 lumens per watt, you’ll get the job done and then some.

So measure your grow area and figure out how many watts per square inch you are looking at with CFL bulbs. 50, 75, 100, 150 is good for watts per square foot. Lower than 50 and your space is beginning to get too large for CFLs to cover with intense enough lighting. I personally grow with 150 watts per square inch, and I’d never go less than 75–and even THAT’S pushing it. SO if you don’t have a small space, go HID.


THOSE are the disadvantages of using CFL lights to grow weed.

By Robert Narley