experiments and overall growth improvements™

I have been wanting to do experiments with weed to make it grow overall better, Ihave some ideas...... one is that when you plant is growing, do you think spreading apart the new leaves that are developing so get more light will improve growth?, also on my next grow i am going to be growing 2 plants in one pot but i am going to have the roots of one plant going in one direction and the roota of the other in the other direction and have the plants twisted around eachother to combine into one, i was already trying this experiment and all was going well but i killed them by accident if i didnt im sure all would have worked out well. Right now i have 6 plants undera 430watt HPS light about 10 inches away, the degrees stays at around 80 degrees,air circulation is good and humidity as well but my plants are 1 and a half months old and only about 4 inches tall with about 4 sets of leaves, all the leaves are close together, is there anyway i can make my plants stretch to make them taller?? i dont know what the growth problem is, never had this happen before

move the light back away from the plant but honestly for 1 and 1/2 months your plant should be ALOT bigger then that... mines only 2 weeks ond and there a little over 4 inch tall with about 6 sets of leafs... so just move the light up like a foot and they will stretch more and spread out... i use cfl lights tho so idk why yours is growin so slow lol...