Cold can certainly be a factor for slow growth.

btw, expecting a 3 y.o. climbing hydrangea to "take off" is maybe overly optimistic ;-) IME, these never exactly "take off" - growth is slow and steady and it can take as much as 7-10 years before they flower (sometimes less).

My parents have one that just took 20 years to bloom.

I hope mine doesn't take that long to bloom. I bought a Wisteria vine from Home Depot and everyone said it would take years to bloom but mine bloomed the second year, and it getting ready to bloom again this year - year 3. Maybe I'll have the same luck with my climbing hydrangea?

Your wisteria was probably grafted - that is the most common way to generate young wisteria vines that bloom promptly (it is the seed grown vines that take endless years to reach blooming maturity). Climbing hydrangeas are not grafted and DO take some significant time established in the ground before they start flowering but the timing can vary on size/age of the plant initially and location.

The discussion about the climbing hydrangea is so timely. They have them in stock at Lowes and I was torn on whether or not to buy. I did seem to remember that it takes decades to bloom. Thanks for the reminder. I think I'll pass.