Last Spring was my first attempt at clematis. I planted four jackmanii vines beneath four 7' trellis. All did well and flowered heavily BUT they all climbed vigorously to the top of the trellis before flowering, "spilled over" the trellis and then flowered with 80 percent or more of the blooms in this spillover at the trellis top.

Will I be able to train them this next Spring to cover the trellis and flower evenly or am I stuck with them flowering all at the top? Is their a guide to pruning and shaping that someone can suggest?

Thank you.