Beginner Gardening: My Grow Light Experiment (T8 vs. T5) , 1 by TLeaves

TLeaves wrote:
The topic of regular fluorescent “shop lights” versus specialty “grow lights” has come up several times. Since someone recently gave me a grow light (T5), I decided to do a little comparison. So, here is a very UN-scientific experiment between my old faithful shop lights (which use T8 bulbs) and my new T5 fixture.

My T8 lights include: 2 four-foot fixtures side-by-side with 2 T8 lights in each fixture and a reflecting hood. I replaced the bulbs this year since I heard that old bulbs get dim and less effective. I didn’t want this to be a factor in my comparison. I bought “daylight” (high spectrum) bulbs. The T8 fixtures are on pulleys so I can raise and lower them as needed to keep them close to the plants. The plants under these lights were kept about 1-2” away from the bulbs.

My T5 lights: A single 2-foot fixture with 4 of the daylight (like around 5,600 spectrum) bulbs. The plants under this fixture were kept about 5-6 inches from the bulbs. There is no need to put T5 lights on pulleys because the plants get plenty of light without needing to be close.

I used all tomato plants in the comparison. They were all planted on the same day, potted up on the same day and in the same type of soil. I used the same variety plant – one under the T5’s and one under the T8's.

Here are the results:

Growth: There wasn't any difference in growth that I could see. Sometimes the T5 plants were bigger and other times the T8. Any differences seemed to be other factors.

Heat: I had expected the T5 light to be HOT, but it really wasn’t. It was a tad warmer, but nothing significant. Later on after the experiment, some larger plants grew up into the T5’s. Some, not all of the plants that came in direct contact with the T5 bulbs showed light areas on the leaves from too much heat.

Color: I was very surprised to see a difference in plant color. The plants under the T5 lights were typically darker green. In photo #1, the T5 plant is on the left. In photo #2, the T5 plants are on the left. Not sure if darker green has any significance, but this was the most consistent difference in the test.

My conclusions after all this . . .

T5 Advantages: Hardening off the plants was easier. After being under the T5’s I was able to move the plants to full sun, pretty much right away. I also liked not having to move the T5 lights up and down which made watering and viewing the back plants easier.

T8 Advantages: Cheaper. Same growth as T5's assuming you keep the lights within an inch of the plants to give them as much light as possible (otherwise leggy). Cheaper. T8's don't give off heat so no issue if plants touch the lights. Did I say cheaper?

UNscientific, but hopefully helpful. Now, if someone would only give me an LED light … (*smile*)



This message was edited Apr 29, 2013 12:21 AM