Lighting Question

Okay so i recently got a ballast or however you spell it from a friend for free and it can hold only one bulb what light bulb should i go with for 2-3 autoflowers. I also would like to know if i need other lights too if so please mention

Well, the ballast will say what bulb you can have

hps.............

You need to match your ballast with the wattage of the bulb. If it's a 400w ballast then get a 400w bulb. Depending on the ballast, I would get an MH bulb for veg and an HPS bulb for flowering. Good luck.