I wouldn't think so. The roses will be absorbing the sunlight through out the summer and will use that energy to produce the buds that will give you the fall flush. Once the buds are produced, the amount of sunlight needed is less. At that point, what is important is temperature. If it's too cold, the buds may not open. But one warm day can take care of that and they flowers last much longer with less heat/sunlight.

Then the lower amount of sunlight will put the rose into dormancy. When the angle of the sun increases in late winter/spring, the roses will start to grow again.

I have the exact situation infront of my house. At the moment I have John Davis, Darlow's Enigma and Carefree Beauty. In the backyard which gets sun all year the two Carefree Beauty roses that I have are bigger and produce more blooms. This spring I am going to be putting Country Dancer in the front of the house because I have heard it can tollerate some shade. I am also going to put a Paloma Blanca and a Prairie Sunrise and see what happens. I am hoping to find a rose that will bloom well in this kind of location. Good Luck with Mary Rose. I am hoping some others with this kind of sun situation will tell us what they have had success with.

Yes, the lack of sun past August will decrease your fall bloom. Unless your fall flush occurs in August anyway. Here, fall bloom starts in September, from buds that formed at the very end of August at the earliest. I have a friend with roses in the same kind of situation you describe, and she gets no fall blooms.

Here there is no such thing as a shade tolerant rose. We do not get enough sun for any rose to do well with less than full sun. You do not say where you are so I can't judge what kind of climate you're in, except northern latitude judging from zone 4! But - a cloudy north, or a sunny north? We're a very cloudy north. You may not be.

But go ahead and experiment! All we can do is tell you what we think might happen. We puny humans are often wrong when it comes to guessing what Mother Nature will do.

Thanks for sharing your experiences. Mine are very similar. I buds forming that don't develop once the plant is in the shade when the fall flush is occuring with the rest of my roses.

reg_pnw7, I am in Western Nebraska, sunny warm days and cool nights.

In the spring I am going to move some roses to more sunny locations and replace with shade tolerant varieties and see what happens.

Thanks again for your comments.