|What is the process and expectations of pruning a trumpet vine to a standard?|
|The trumpet vine, Campsis radicans, is a very large and gangly fast growing vine so I am not sure it would be a good candidate for this treatment. On the other hand, it does bloom on new wood, so if you pruned it back very hard in the spring then it would still bloom for you that summer.
To make a standard however you would probably be hoping for a fairly upright "trunk" with a tight flower-covered head and with the growth rate of this vine I think you would be disappointed with the end result.
If you want to experiment, you could take several main sections of vine growing from the ground and tie them upright to a sturdy central stake. Trim them off at the top of the stake now in spring, and perhaps trim them several more times during the early spring to try to make the plant branch at that point. If it tries to sprout from the base, trim those new base sprouts off and only allow it to grow at the top of the stake. Rub off any growth along the "trunk" as well.
Then you will need to let the top bits grow because they are where the blooms will be. They may reach six feet or more in length before it is bloom time. Remember, do not prune it during the summer or you will be cutting off the flower buds. Each spring, trim it back hard to the top of the stake.
An alternative might be to let it grow up a pole or post; one of the most impressive trumpet vines I have ever seen had swarmed an entire telephone pole and was blooming its head off. It was never pruned over many years, instead it was allowed to do its thing naturally so it branched out when it hit the top of the support.
Good luck with your project!