Qualm entered English in the 16th century, with meanings like doubt and uneasiness.. Usually a qualm comes from doubt about an action and a feeling that you are doing, or are about to do, something wrong. It isnt a bad feeling about another person's behavior but about your own.
The newest type of grow lights use LED technology. One major advantage to the LED lights is the small size. LED lights are only a few inches in diameter and are easy to mount. In some greenhouses, LED lights may be the only practical light option.
Blue light, for example, helps encourage vegetative leaf growth. Red light, when combined with blue, allows plants to flower. Cool fluorescent light is great for cultivating plant growth indoors. Knowing that different colors of light can affect what a plant does is important in a world that depends on plants for food. Advanced LED technology is now making it possible to control the kinds of colored light we provide plants in controlled environments.