Hydroponic systems are often indoor systems positioned in places where there isn't access to direct sunlight all day long. Most edible plants require at least six hours of sunlight each day, with 12 to 16 hours even better. So unless you have a sunroom or other such space with lots of window exposure, you’ll likely need to provide supplemental grow lights. Hydroponic kit systems usually come with the necessary light fixtures, but if you are piecing together your own components, you will need to buy separate lighting fixtures.