I've had a couple of girls keep stretching while I was gone for a week. They just stretched and stretched, until I finally just threw them out.

What I normally do , is bend the tops over to the sides. By this I mean not snapping them, but I just taking an area of 3-4", and squeezing the stems near the top until it almost looks like it wants to grow DOWN. So all I really do is flatten the stem without kinking it. I feel it is better than cutting the tops, and it keeps the canopy of the plants nice and even, and it 'confuses' the plant to not grow lengthwise and so then it starts filling in.

In your case you could have some lemons instead of great plants. I paid $250 for some seeds from Amsterdam, and after six months, I finally threw them all in the garbage. The buds just came out like little cotton balls....

sn