the reason you have such a bad stretch is b/c of lack of light/lumens. for a plant to stay short and stout, there are a number of thing's you have to do. ONE: MORE LIGHT!, the more lumen output each light has, the closer the internodes will be, hence shorter and stockier. TWO: Lower your lights. THREE: A FAN, fan's tear the fiberous tissue in the plants stalk thus building more tissue on top of the torn tissue creating a sturdy, healthier stalk. Moral of the story, PLANTS CAN'T HAVE ENOUGH LIGHT! GET MORE!