Roses are complete greedy guts, They seem to take everything you can give them and more.
However in your cold climate, I wouldn't feed them at all after midsummer. That would only promote soft sappy growth, and cause even more winter kill.
Daisy

My roses just go in potting soil.

The thing to watch is that there is a direct relationship between watering/fertilizing and the porosity of the soil. A lot of traditional rose people like a very, very quick draining soil which they then water and feed several times a day. During a fairly normal summer here, I won't water the pots more than a couple of times, so I need something that holds water.

I use good potting soil as well then supplement monthly with alfalfa/manure tea alternating with fish emulsion and mulch with coffee grounds when I have them. No rain here in the summer so watering is frequent. I read somewhere that inorganic fertilizers can build up salts in a potted rose so I use only organic compostables for my pots.

Diane

My potting mix is similar to the above recipe. My base mix is topsoil (Black Kow), composted manure (Black Kow), sand, and aged pine bark fines. I also incorporate blood meal, bone meal and super phosphate, but in smaller quantities than specified above. If I have cottonseed meal or pre-moistened peat on hand I may add that too. The last thing I throw into the mix is a big scoop or two of perlite. Altho perlite helps with drainage, I use it primarily as a visual aid of sorts -- once those stark white granules are distributed uniformly throughout each large batch of mix, I know that ALL the ingredients are evenly distributed.

You mentioned that you've been curious about using sand in your mix . . . If you decide to use it, I suggest that you avoid the very fine sand. I prefer to use the coarse sand that's labeled as 'medium'. It costs a dollar or two more for a 50 lb bag. Many packaged top soils (like Black Kow) are mixed with sand to keep them friable. Adding additional sand to the mix enhances drainage and delays compaction. Personally, I think it's an essential ingredient.

The thing I keep having happen is the pot will get waterlogged and I can't get it to dry out. Pretty soon the rose is sick. My husband moved two five gallons for me the other day and pointed out one weighed twice as much as the other. The heavy rose is pretty sick. i've been giving it a cup of water once a week trying to get it to dry out.
It's not working.
You might be right about the inorganic fertilizer, Diane. Best luck I ever had was rabbit manure tea. The rabbits have gone to history, though.

For this last batch of roses in biggish pots I used a mix of Fafard 3B which is a soil-less potting mix about half & half with composted horse manure, and some epsom salts & Rose-Tone along with my usual planting practice of alfalfa pellets, milorganite, bone meal & mycorrhizae in the hole. The Fafard is very light and not cheap. Then I topped it with small pine bark chips. Since planting, they've gotten milorganite and alfalfa/fish/seaweed tea once each. I think the soil-less mix helps with drainage. Mine get daily water.

Sherry

Sorry to be so blunt, but there's no excuse for having water-logged pots. What's the composition of the potting medium? Does the pot have drainage holes? If so, is the pot elevated, or does the pot's bottom have direct contact with a hard (or poorly draining) surface? If the pot is not elevated, is it placed on a surface that does allow proper drainage -- gravel, a deep layer of bark mulch, or other coarse material? Potted roses are wholly dependent on the gardener. To thrive, they generally require frequent watering and PERFECT drainage.