Since no one else has replied, I'll jump in. All depends on which cultivar you have. Which passionflower do you grow? There are many named varieties & cold hardiness varies with each one, so start with knowing which one you grow & its reaction to cold temps. Would think in your zone most would be root hardy if not cane hardy, so mulching the root zone would be sufficient unless your vine is only rated for zones 9-10.

Is this a young first year plant in your garden? If so, the root mass may not allow the canes to survive its first Winter. I would not prune back the vine. My Blue Bouquet died back to the ground its first two Winters, but resprouted from the roots to grow strongly & quickly each Spring. When it gained enough root mass with more maturity, it was able to overwinter its topgrowth, even keeping most of its leaves. The main stems got thicker, turned brown & woody & weren't phased by cold down to zero here. Autumn thin stems usually were too new to survive, but a few always managed to. Those that didn't were clipped out in early Spring, back to live wood. Dead leaves were left as insulation till then as well.

Here in central Virginia, we usually have mild spells periodically during Winter. Found it's important then to water the roots during these spells if no rainfall obliges. Also make sure to water them well before cold spells are predicted in the Fall, so the ground is moist before temps go down.

Four Blue Bouquets were planted here in '99 to grow up front porch pillars & span the arches between. The base of the porch is stone, which likely keeps them warmer than they would be further out into the garden. The porch faces ESE & the passionflowers are protected by the house from cold & drying prevailing Winter winds from the North & West in that location.

Is your trellis & passionflower located in a Winter-protected spot? Depending on your variety, where you have it sited & what size it's attained so far, different protection measures could be used in its early years. Let us know the passionflower you grow & it's garden position, and we'll brainstorm how best to protect it.

This post was edited by vasue on Sun, Sep 28, 14 at 14:18

Leave the leaves as is for any last-minute growth and food production.

It should die back on its own as the first few frosts come through. You may have mild winters but at least a few frosty nights should still kill the top part of plant. At that time, go ahead and remove the dead growth.

It should return in the spring, stronger than ever. And since you didn't have it in a pot, you probably should get many volunteers in and around that first plant also. It's up to you if you want those extras to grow also.

I found my passion flower at the Montrovia website. I've pasted the link below. Sorry it took me so long to get back to you all. It looks like it may have survived the winter months. We get lots of rain and mild winters here.

Ooops, here is the link (I hope it works)

Here is a link that might be useful: Passiflora