Lemon-ups lack of something or fall fade

If you watched the 4x4 video you will see I talked a bit about the lemon-ups fading quite early every time I have grown it.

I figured this had to do with my soil but maybe it has to do with my soil missing something when the plant is getting close to the end?

Either way this is packing the Trichomes and looking like it may be a good yeild.

Here is the video incase you missed it.