Deciding on the best grow light system is one of the most important and expensive decisions you will face when creating your grow space. The lighting system you decide to use can have a huge impact on growing plants such as tomatoes indoors. There are many things to consider when deciding on the lights that will work best for you.
When doing research to see what light is best for you, keep in mind that there are four main types ofgrow lights: incandescent, fluorescent, LED, and high intensity discharge (HID). Incandescent lights are not used much due to their low lumen output. Fluorescents however are used all the time for the vegetative stages of growing as well as maintaining mother plants and creating clones. Just remember that these lights are not very powerful either, so you may need more bulbs than you expect.
High intensity discharge (HID)grow lights are the most popular choice for indoor growing. This is because of the high lumen output and the spectrum of light they emit. The downside is that they give off much more heat, are more expensive, and require additional maintenance. This all comes with growing indoors though!
There are two main categories of HID used to grow indoors. Metal Halide (MH) lights are used during the vegetative stage of growing because of the specific light spectrum that is released. High pressure sodium (HPS) lights are used for the flowering stages to help grow big fat buds. Most people will buy a grow light ballast that is one or the other and will use that ballast for that particular phase of growth. It is possible though if you have a small growing area to use a convertible ballast which allows you the grower to change the bulb between MH and HPS when needed. You would simply just have to change the small switch on the ballast.