Cost is generally the determining factor between the two types of grow lights. LEDs are more expensive but last a long time and use less power. Fluorescents are cheaper up front but use more electricity than LEDs. LED grow lights also run cooler than fluorescents, so you can put them closer to plants for better growth results. Go with fluorescent grow lights for large indoor gardens for an economical choice. Keep in mind that fluorescents contain mercury, so take care not to break the bulbs. Overall, for the strongest indoor plants, choose LEDs when possible.