Does the light have to be at the top?

[emilya]

I did manage to get 2 of the tallest plants to bend over last week by about 12-16 inches but even the leaf stems off the main stalk have regained the height i saved last week, they are growing like crazy. The plants are about 5' (1.524 mtr) at the moment does anyone have a rough idea how much taller they might grow

this depends a lot on genetics. Different strains stretch at different rates the first 2-3 weeks of flowering. General average is that they add about 40% height at this stage over where they were when you switched to flowering. Regarding the bending... don't be too timid... don't break them either, but consider a SCRog grow where you bend them 90º at the 10" mark. They just keep growing sideways. In LST you bend the top down BELOW the height of some of the secondary growth, ie more than 90º, and it produces a hormone that tells the plant to accelerate growth in the secondary branches making the plant bush out. These plants can adapt to all kinds of crazy things... give it a try. 5' tall is pretty tall though, you might want to get some stronger and closer light on them in the veg stage next time and keep them shorter. For instance, my plants were only 14" tall after 9 weeks of vegging.

Emmie