DIY CFL Grow Light
Author: Jared Bouck
Project Cost: 25.00
Est Construction Time: .25 Hr
Required Skill Level: Can you screw in a lightbulb?
This project was a personal experiment that i did to learn about lighting options for the growing environment. And as it usually turns out, the results were better than I expected. So I decided to publish my findings here so others can use and experiment with them. Utilizing 4 CFL bulbs I was able to get results that were satisfactory for the vegetative phase of plant development for a fraction of the cost commercially available systems.
For this project we will be using a high wattage home type CFL bulb. Rated at 23 Watts Actual ( 100W incandescent equivalent) and they need to have a color of 6500K for vegetative growth. The nice thing about these bulbs being modular is you can mix colors by just swapping out a light bulb. So you can slowly shift to the flowering / fruiting red color spectrum gradually over a week to reduce stress on your plants.
Light Cord and socket.
This is just a cheap socket and cord fixture from the home improvement store that I picked up for this project. Ideally you will want a ceramic fixture for more rugged use, but this is good enough to start with.
This is a simple 4 bulb fixture. These are usually used in photography as the fixture in soft boxes. In our case it works well for a grow light as well. Note the all plastic construction. This is designed for use with CFL BULBS ONLY. They produce far less heat than incandescent bulbs.
So assembly is unbelievably simple for this project. Here I just installed a light bulb into the fixture for sake of comparison. If you can screw in a light bulb you can make this grow light.
Here we have another shot of the 4 bulb fixture. You can see the back is just a normal screw in bulb end.
The assembled unit all ready to go. Not more I can say other than don’t drop it at this point.
Here we can see the bulb in my little grow room glowing away. These bulbs do put out a bit more heat than I expected. Not a ton, but enough you will want to give it a few inches of clearance from your plants.
Our seedling in the drip system project soaking up the rays.
Here we can see the bulb next to a professional hydro farm 150 watt CFL fixture. Now the real question is how do they stack up?
Ok… so now how does it compare? I was seriously surprised to see what happened when I started taking measurements. So our basic rig is a PVC frame holding the fixture 16 inches from the testing media. We have marked this 4 FQ foot foam board out in a grid so we could measure the results. Here we are using a high end LUX meter to take the measurements. all values have been rounded down for ease of display of information.
First we have our simple DIY CFL grow light. It peaked out at 15,219 LUX in the center of the fixture.
Next we have our HydroFarm CFL 150 Watt System. This topped out at 14,385 LUX but had a much more even spread.
Numbers numbers numbers… So who won?
Well that all depends on how we interpret the data. Without question the Hydrofarm fixture at 150 Watts put our far more light than our 100 Watt CFL fixture. However that is not the full story. The foot print of our fixture is only 1 SQ Foot. where the Hydrofarm fixture takes up substantially more space. In fact in a 3 foot square grow room you can fit 2 hydrofarm fixtures and that is all! No room for any other bulbs. In my situation I have 4 Buckets and I have 2 plants per light.
That being said we can install 4-6 of our fixtures in the grow room and provide substantially more light per plant than the Hydrofarm systems can. But wait you say… We can get 200 Watt bulbs for the hydrofarm system. That’s super. the Light output will be slightly more, but the Combined wattage of 400 Watts can be met squarely by 4 of our 100 watt systems and then exceeded in density with 6 fixtures.
Am I saying that hydrofarm sucks?
Not at all. I have 2 fixtures and l love and use them. But I also now have 6 of my fixture and I am very happy with how they perform. In our test we tested the bottom facing illumination only. With the large reflector the hydrofarm system directs the majority of its light directly out of the bottom. With our system we don’t have any type of reflector or hood and because of this we get a lot of cross and side lighting that is not a bad thing at all! I have thought of putting a simple hood on this and retesting to see how it performs with the light being directed downwards, but we already have a strong hot spot that would be hard to improve upon.
All things said, this is absolutely a low cost and viable way of lighting your plants. we hope you try it yourself!