Irydyum is correct, you may be the first person asking how to grow taller, lanky plants. (I went to give you rep Iry, but I got to spread the love around first, I owe you one :thumbsup

Zompton, LSTing is a method to fill out a canopy and used to hold heights down. Trimming to allow more light to the bottom will just slow the growth.

Consider chopping the plant's top when it is finished, lower your light, and let the bottom finish flowering. If it has buds low that are smaller and immuture this will get them to plump up and finish better.

Good luck and good growing.