I keep this plant in my small sunroom late Fall until May. Zone 5. Flowering this year for the first time! When I bring it in for the winter, I would like to prune it to a more manageable size. Would this decrease flowering next year? Also, not sure when it may need a larger pot? Thank you!
Generally, once the flowers drop it will be time to prune it. You can prune to your desired height. As far as when it needs a larger pot- You will know when roots start coming out of the bottom holes, and circling inside of the pot.
Here are some articles that will help:
https://www.gardeningknowhow.com/ornamental/flowers/iochroma/iochroma-plant-care.htm
https://www.gardeningknowhow.com/houseplants/hpgen/learn-more-about-repotting-houseplants.htm
I have a Royal Purple lochroma that did fantastic this summer in full sun in the ground. I live in Zone 8b (NE Vancouver, WA) & the leaves died with the first frost. Should I prune the plant back or let it be? So far, the stem are good.
If the stems do not die back, just lightly prune it for desired height. If the stems die with a few hard frosts, you can cut it down to a few inches from the ground and it will resprout in spring.
https://www.gardeningknowhow.com/ornamental/flowers/iochroma/iochroma-plant-care.htm