The best chance I have for notes and soil in my town is lowes. I don't feel comfortable buying notes and soil offline. So what are my best choices? Oh and I plan to upgrade my cfl Closet a little this weekend. So I ask this. About how many cfls will I need to grow 6 medium size bushy plants maybe even a scrog? So how many would work without using too many as I'm still in a 2 ft wide space with 3 ft of height. I plan to just cut a hole in my wall to route hot air out but that can't happen until next week or week after. So ill still have to leave the door open for some time.
There are lots of formulas that growers can use to determine how many CFLs they will need.
For example, some growers recommend that you go by the amount of lumens (light) produced, or by the total wattage of your lights.
However, I think a simpler approach is much more effective, and will result in better yields for you.
Simply follow these principles with CFLs to get great yields every time:
- All parts of the plant should be within 8-10” of a CFL bulb (CFLs should be kept 2” away from the tops of your plants
- Any “shadowy” areas need another bulb
- More bulbs = better results (You want to surround your plant with as many bulbs as possible because the penetration of CFLs is poor; in other words, more small CFLs is more effective than a few big CFLs)
Real-life Example: 7 x 26W CFLs (at 182 watts total) that are spread in an array around the plant will be more effective for growth than 1 x 200W CFL, even though they use less total electricity.
- More lumens = better results (you can’t really give your plant too much light when growing with CFLs, more is better)
- In the flowering stage, make sure that buds get direct access to intense light & keep CFLs as close to buds as possible without burning them (this will dramatically increase yields with CFLs)
The size and shape of your plant is going to have the biggest effect on how many CFLs you’ll need, and that’s why no “formula” is going to be accurate all the time. Any formula is just a rough estimate.
What if I’m still not sure how many CFLs to get?
You can use this formula to get started with planning your grow space, though I recommend using the guidelines above once your plant has actually started growing.
4,000+ lumens/sq foot (more is even better) - lumens is the measure of light as perceived by the human eye, and this number will be listed on the CFL bulb packaging
Example of Estimating Number of CFLs Needed For Your Grow Space:
- Multiple width x length of your grow space to determine the sq feet.
Let’s say your grow space is 2’ x 2’ = 4 sq feet
- Multiple the sq feet of your space by 4,000 lumens to determine the total lumens needed for this space.
So 4 sq feet x 4,000 lumens/sq feet = 16,000 total lumens for that space
- Divide this number by the lumens produced by each bulb
If you’re getting 42W CFLs which are rated at 2,650 lumens apiece, that would be 16,000/2,650 = ~6
- This number is the minimum number of CFLs needed for your space
That means in this case you’d start with 6 (or more) 42W CFLs
Remember, this formula is just an estimate, and you will get the best results if you also follow the guidelines listed above.
Tip for maximizing the light to your plants: Use the power of reflection to minimize light loss. Cover your walls with reflective mylar or paint them with flat white paint. Utilize reflectors to aim more light where you want.
