I had the same issue in my last grow where I started with 8 plants in a 1.2m x 1.2m tent but then I downgraded to a 90cm x 90cm.

2 of the plants were much stronger than the others and quickly outgrew the others. This created a battle between the plants which was stunting all of the plants including the 2 strong ones.

The only solution I had was to take 2 of the strongest growers and kill the rest. I took all the plants out of the tent and I had a look at their development.

The plants which didn't develop well were killed and so I was left with the 2 strongest and most developed. As soon as I cleared out the tent the remaining 2 plants exploded with growth.

The buds started to pack on and even on the lower branches as the light penetrated much better. It was the best decision I could have made.

In my current grow I have only 4 plants in the tent. They all get an equal amount of light and nutrients. Everything is working out well so far and the ladies are just blooming.

I don't expect them to stretch too much. the nodes are quite tight and the plants don't need to fight for the light. I use and LED light, the Pro-Grow 260 and 80w of CFL just for heat.

If your plants don't have to grow over each other to get the light they need they won't focus so much energy into stretching.

Keep the best 3 or 4 plants, but no more. Maybe you can get another light and tent for the rest, a Weeze mentioned.

Hope this helps.

You can see the issue I had in the first grow in my signature.

Take Care

S.L.