Since they are in the Ground, and have no Lips to lean on, the PVC should work Great! I would have done it the exact same Way, BTW, I like the way You used a Cinder Block, I believe it is, to weight the other end down. This kept my Plants at a Manageable Level, till Harvest Time. I have no Name for this way of tying the Plant Down, it just came to Me after some Thought for a few Days. Improvisation is what I like to call it! Well miwa, I hope You like this way of Growing. I would not Steer You wrong, I Promise! SINCERELY, JAMESTHEGREEN.