Trying to grow a Passiflora
I am in MA, a bit north of Boston, and I want a fragrant flowering vine on an arbor next to my patio. I spent last winter looking, and went from a climbing rose (too much work with the time I have available for the garden) through tons of others, and arrived at passionflower. I read all kinds of stuff about how well it grows, but figure the winters here will help to keep it under control. So, I planted two. Facing this arbor, the one on the left actually gets more sun, and should have been fine, but it did not survive. The one on the right faded, but is now coming back. I have one tendril about 2' long with what seems like skimpy leaves, but over the last week it seems to be adding several inches a day. The tendrils are grabbing any and everything they come close to, and I keep unwinding them and putting them back on the arbor. It should soon get high enough that the arbor is all it has to climb on, if it keeps going the way it is now.
Since we don't freeze for a couple of months, it has time to grow, but I'd like to ask if anyone knows any tricks to help it along? Is there some particular nutrient I can bump up to make the roots stronger so it survives the winter and comes back ready to thrive next spring?