Hi Chelsea –
The type of light or system you will need really depends on how much light your plants will be receiving in the window as well as how many plants you have. If you’ve got them located in a south facing window, additional lighting really wont be necessary. However, should you need another light source I would recommend something much simpler than the bulb, ballast and reflector combo.
The first option would be to install a few of our basic Agrosun 26W CFL bulbs. They are extremely efficient low energy light bulbs that screw into normal sockets while providing full spectrum daylight. They can be placed closer to plants than any other bulb so if you have a small number of plants I would recommend installing these fixtures into a small clamp lamp – or check out our AgroSun DaySpot Grow Light Kit.
If you are trying to provide light to more than just a handful of plants, my favorite lighting system is the T5 Fluorescent Lighting System complete with full spectrum bulbs and a built in ballast. They are great because they come in one piece and just plug into a normal 120V outlet. They also come in a variety of sizes so depending on the number of plants and the amount of space that they take up will determine the size of the system you will need.
It is easiest to hang a T5 from screw hooks in the ceiling with a simple ratchet system. Although, if your plants are not very tall then check out our Jump Start T5 Light System Kit that comes with a 2 foot stand that the light can be raised or lowered on.
Finally, once you select the best system for your set up, I would strongly recommend installing a light timer to ensure that your plants are consistently getting at least 12 hours of light each day, on a regular schedule.