I live on the coast, so roses are challenging to grow well. Whether they're in the soil or planters that I can move around, they get whitefly and powdery mildew and never really thrive. Sure, I get a bloom, but not a full bush like my Mom in NY has. Initially I didn't want to inhibit their growth, so left the canes intact and tried fertilizers, soap concoctions and other non toxic treatments to combat the flies and mildew. That was a mistake since having researched and now executed a better plan, I have a better solution to keep them thriving.
1. FEED: Roses love Epsom salt. The magnesium helps them stay green and increases the number of bloom by causing basal breaks. It also seems to make the bush resistant to insects when sprinkled around the base. I also found that a 5-5-5 non-chemical fertilizer like fish or kelp provides the building blocks for growth and bloom. Alfalfa meal sprinkled at the base promotes and conditions the soil for plant growth and I have a vermicompost container (Blog) which adds nutrients and organic matter that improve soil.
2. PRUNE: Pruning is ESSENTIAL for healthy roses. You can practically take hedge clippers to a rose bush, and it will grow back vigorously. I trim throughout the growing season in CA which is March-October and reallyI trim by cleaning off unwanted growth and stems that cross. I choose to trim at buds that face out, so the new growth shoots outward and not towards the center. Make a cut about 1/4 inch above the bud and slant your cut parallel to it (about 45 degrees). For spring pruning, I'm more aggressive in what I cut off. I look at the stems and make sure they're green or white. Sometimes I just cut lower to get a healthy stem. I try to have all stems growing outward and not angled in to the center. I cut the canes just above an outward facing bud and DO remove anything that looks thin since the weight of the bloom can be too much for the rose to support and it will spend energy there that is best used to develop new growth. If shoots have come up through the root I cut them back and remove any canes that are crossed so the remaining ones will grow stronger.
3. OTHER CARE: Mid-spring is a good time to thin roses as you see new growth. Your bush will thrive if you remove thin shoots so the bush can expend energy growing and not supporting those shoots.
Deadheading should be done all the time. It encourages new growth.
I don't have to worry about winter cold but wouldn't advise doing any cutting in winter unless you have damaged canes. In really warm areas though, pruning when it's cool will enable the bush to store energy for the first bloom.
Hope this helps! Send your garden images and will post!