Do we need to leave the plant in the ground over the winter, or trim to ground level or dig up and keep indoors until Spring?
Certified GKH Gardening Expert
This depends on if you have an annual or perennial lobelia. There are many species, and each have different care requirement. They won't tolerate freezing temperatures well, so if it gets cold in your area you will have to dig them up. Here is a collection of articles that will help you care for lobelia: https://www.gardeningknowhow.com/ornamental/flowers/lobelia/