What moyboy said mate, 4 hours is no where near enough light, for seedlings / young plants you really want them to be on 18 hours of light, or at least 12, less than that they will think it's winter and will go into hibernation or just grow very slowly, as is evident. At the three month mark your plants should be at least a 1 - 1 1/2 feet high.
Go down to bunnings and buy some strong CFL's (compact fluros), about 24-28 watt or higher if possible, and keep them a inch or two above your plants with a small fan blowing on them ... (keep them undercover/inside), the fan is not for the heat of the fluros, but to get your plants to grow stockier stems to support the weight on the fruit.
Remember, an inch or two above your plants, any longer and the intensity of the light gets too weak. I would throw at least 1 CFL per plants to begin with, maybe 2 just to get them a bit bigger, then plant them in a full sun spot.