Ask Mr. Smarty Plants

We are also at a loss about two things: How on earth did you transplant a vine that size? and (2) What is it doing growing in Minnesota?

The first question has to do with the fact that a plant growing that long in one place must have had one heck of a root. If it is still growing and putting on buds after that kind of move, we have to tip our hat to whoever did it. The second question is that both of the native plant candidates  to be a "trumpet vine," Bignonia capreolata (crossvine) and Campsis radicans (trumpet creeper) are hardy from USDA Hardiness Zones of 6 to 9 or 6 to 10. Hugo, in Washington Co., MN, is in Zone 3b, where annual average minimum temperatures are -35 to -30 deg. The closest that crossvine grows to Minnesota is the very southern edge of Ohio. The nearest the trumpet creeper comes are counties in the very southern corners of Wisconsin and Ohio. 

However, whether it lives through the Winter or not, we think the best possibility is that you have Campsis radicans (trumpet creeper). Probably, that far North its invasive tendencies are not going to have a chance to get going before it starts freezing back. Both vines are considered native to the southeastern United States, and both can become somwhat invasive, climbing up trees or buildings and putting out suckers all over everywhere. While trumpet creeper is beautiful and a prolific bloomer attracting hummingbirds, it can be a pest in the fields and has a sap that can irritate the skin. It is sometimes referred to as "cow itch" or "Hellvine," if that gives you a clue. 

Either plant is going to bloom better if it can get up to the sun, which may be why you have buds up high, but none down low. If the buds are breaking up high, the roots are alive. We would do no trimming unless and until it did start to get invasive, and then only to control its spread beyond where you want it and nipping off suckers if they appear. We would suggest that as soon as the blooms and leaves start to drop that you trim it down fairly close to the root area, and then cover that with mulch. If the roots freeze, the plant is dead, regardless of what it went through to get transplanted.

From our Native Plant Image Gallery:

Bignonia capreolata

Bignonia capreolata

Campsis radicans

Campsis radicans