During the winter, my days are short, the sun is low in the sky and it's often cloudy or raining. I use artificial lights to get my garden plants growing strong by the time I can set them outside. I used to use fluorescents in various configurations. For several years I've been using LEDs. They work very well, don't overheat, and my plants are healthy. They also get whatever daylight comes through the glass in the sunroom, but this time of year most of the intensity and day length is via the LEDs. I keep them quite close to the plants, 6 inches or so. They are mixed wavelengths.