Caring for my Plant

My plant is now about 2 inches tall and if I had a garden I would be transplanting it in it, but I don't.  I've been supplying it with plenty of water; in fact, my regular routine has been varying according to how hot it is outside.  On colder milder days I don't supply my plant with that much water.  When the days are cooler it is noticeable that the plant takes in less water, so I keep the water supply on a low side.  I'm debating if I should began rasing my plant inside my apartment instead of outside.  It seems that the cold at night is keeping the plant from growing at a faster rate; before the plant seem to be sprouting at a faster paste with the hotter weather.  Looks like I might be looking into buying some indoor lights to supply my plant with heat if the weather begans to stay more on the cooler side.  I'm trying this Fertilizer Spray to see if I can get quicker growth.  Fertilizer Spray