Baby vines and blue grow tubes.
Blue X grow tubes are designed to protect young vines and speed-up early growth while also promoting upright growth. It’s not only the shape, but something about nature’s beneficial blue light and the temperature inside the tube. Maybe it’s hooey, who knows?
For our first vineyard block we used paper grow tubes; basically elongated milk cartons.
They were okay but I believe they promoted mildew which is a problem in our climate. Tubes in general prevent the circulation of air and make it hard to spray young vines which does not help. I’ve brought this up at several seminars but there is no evidence that grow tubes promote the growth of mildew.
For our PIWI Solaris hybrid vines, I followed the French tradition and let them grow free for the first year. Lot’s of air, sunshine, and free to roam.