Mine regrew after a fairly severe haircut, but do it after it's flowered. Early flowerer.
Mine survived a fairly severe haircut but was never pleasing to look at after that. I'd start again
Hi i took for the first time 4 cuttings of Rosemary last year just stuck them straight into the soil and they are just magic ,i dont recomend this way i think a little more time and care next time in proper cuttings soil but Hey it worked and Rosemary is so easy and seems to be a tough plant ,in Falmouth there is a 12 foot high wall covered with rosemary growing from the garden at the top its all just hanging there in summer its just stunning
This rosemary grew enourmous and had dead bits on it, so about 4 or 5 years ago I dug it up and found the lower branches had rooted in several places so I pruned the best looking bits quite hard and re-planted them. I now looks like a big bush, overflowing it's bed again.
you can clip it like a hedge with shears,my son has rosemary hedge and we clip it twice a year.