I planted a Clematis montana when our son got married quite a few years ago. I planted it beside an Ash tree, expecting it to climb to the top and then prettily cascade down again. That was the idea anyway, but the clematis had other ideas.
Plants have their own ideas of where they are happy flowering, I have tried a few times to train the clematis up the tree, but I think now I will let it find its own way to wherever it wants to go. I like my plants to be happy.
This same ash tree has Rosa Wedding Day up it. This was planted to mark the wedding of our daughter,it has taken off beautifully, climbing right to the top of the tree. It will flower in about a month’s time, just as the clematis is finishing.
I like this sort of gardening, just plant it, let it do it’s own thing and fling a handful of fertiliser onto where you think the roots are, once a year!