I may take up to 1/3 of the height off strong-growing shrub roses after each cycle of bloom in order to encourage more branching and compact, upright growth. And that's after substantial pruning as growth begins in spring, sometimes removing a few older canes at the base as well as cutting back about 1/3.

However, that's not a universal prescription. We might be able to give better advice if we had pictures along with your location and the rose varieties.

Pruning will not kill roses, except occasionally when very old and neglected roses are cut down to the graft, or if the graft is cut off.

Michaelg is right about pruning not killing roses. The deer have pruned the roses in my front yard for years, until I finally caged the roses, and they didn't do it on time or correctly.

However, there is a caution ... if you live in a climite like mine where we generally get triple digit temps for weeks on end or longer, you don't want to take off all of the leaf canopy and leave almost all of the plant with bare canes. The canes will get sunburned, which leaves them vulnerable to insect damage.

So, the real answer is "it depends"

Smiles,
Lyn

As said above, it would really help to know what the roses are, where you live and pictures would be a plus.

I'm in the process of systematically cutting back my larger bushes. They've gotten too big for me to handle and deadhead, especially from my scooter. Bushes 6 feet tall are being cut down to one foot. So far everyone I've done has come back nicely. Several large Explorers and rugosas have been cut back or are being done. My goal is to get them all done by mid July.
All mine are own root so I don't worry about grafts.
My advice: Don't be limited by the 1/3 or 2/3 rule. Cut back what you want.
BTW, I expect mine to bloom again this season. Some repeat bloomers done earlier are already setting buds.

I agree it depends wildly on where you are.

I actually prefer to do mine during the growing season because winters where i am get cold enough to kill new growth but not reliably cold enough to induce dormancy.

They usually bloom after pretty severe cut-backs.

I usually do a big prune after the spring flush, especially on bushes that have gotten gangly, are flopping over from the weight of blooms + rain, and ones that I didn't prune enough in the early spring. You will set them up nicely for the next flush, even if you delay it a bit. I usually do this again in late summer to set up for a fall flush, but my season may be longer than yours.

Hi everyone-thank you for all the information! I don't have any pics at the moment-I am in CT if that helps. I've been told they are tea roses, cape cod roses, shrub roses. Not sure what they are-they grow in masses-6-10 medium sized white blooms off each branch-probably about 2000 blooms per bush. Very light fragrance. I will attempt cutting back a few this weekend that are not really visible from the street in case they look horrible. I'm cutting off most of the green new growth, so I was worried exposing much of the underlying older wood could damage the plant.