Wisteria Floribunda Longissima & Brac Shiro Kapitan

Will be planting in next few days. Got great buy on both these plants. These vines are 1" diameter and 5 feet tall already!

Question: hear they are super hard to achieve bloom - what's the secret????

I heard that you have to have ONLY the main stem for wisteria to bloom, have to cut off all the little runners!! I did that and left about two to three inches on each runner at the base of the wisteria - noticed the other day they were starting leaves, so today I cut them right up to the main stem, and four of the seven had sent roots, so I carefully pulled them out and my gosh, I think I'll have four new wisterias!! (Well, my neighbor has two!) Now, the other four have leaves but no roots, so I have them soaking in water, not sure what to do. Hmmmmmmm.

My Wisteria is on a large trellis attached to a retaining wall. I planted it two summers ago and this year it is already covered in flowers, but only at the top of the wall where it receives full sun. The other 6 ft of it that receives about 5 hours of afternoon sun has no new growth, leaves or flowers. What should I do to get growth on the old vine? Should I have cut it back after last season and allowed it to regrow?