Loofah's 2013

I live in NY, and I've decided to try and grow Loofahs, I started them indoors around February 20th. They sprouted and quickly went upward under the artificial heating and lighting conditions I have available at home. However, lately they've taken to flopping over, I'm wondering if I'm not providing enough heat or more small trellising or something else is missing? They also seem to have slowed growth at 6" and I'm just wondering about that too.