Some people don't cut theirs back but I like mine to have a fuller foliage mound. My mom always cut hers back, rooted some of cuttings, and she had beautiful plants and flowers. Wait until early spring if you're going to trim them up. You can ask Shelley what she does with hers as I don't think she cuts hers back.
@sieveheadsarah thanks Sarah 😁 there’s a little family-run greenhouse just up the road from me. They only grow annuals but it’s just a massive greenhouse crammed full of gorgeous plants. They always seem to perform better too 😊