Different Sizes of Fluorescent Grow Lights

Fluorescents are typically labeled T5, T8, or T12. The T designates size by diameter. T5 tubes are about the diameter of a dime, while a T8 is closer to a nickel. T12 tubes are the largest. As their diameter grows smaller, fluorescent lamps get more efficient. A T8 fluorescent tube will be more efficient than a T12, and the T5 tubes are more efficient than both.

I use a large 8-lamp HO T5 fluorescent fixture to light and grow a rotating group of houseplants, herbs, orchids, and young transplants.

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