I had heard that this plant takes years to finally flower, but these are covered with flowers and flower buds in just 17 months from seed. What I did was to prune off two feet of the ends of the vines when new growth reached or exceeded six feet. The plants sent out new runners at the first node next to the cut. Flowers and flowers buds occur (for me) only on the new runners, when they reached 2 to 3 feet in length. There were no flowers or flower buds on vines which had not been pruned.