do gauras need any trimming during the growing season

Question

see above

Answer 1

You can cut Gaura back once by one-half when the plant is about 12 inches tall for a bushier plant with only about a one-week delay in blooming or cut it back to about two-thirds its unpruned height one more time in midsummer for blooms starting in late summer on a compact plant.
https://www.gardeningknowhow.com/ornamental/flowers/gaura/growing-gaura-plants.htm