It's hard to tell without looking at your soil, but I am going to make a guess based on my own difficult experience. My garden soil is terrible, a gluey, rockfilled mess that has been amended by myself and the previous owner, but I slowly learned with the overwhelming mess of clay and bottomless number of fill rocks large and small, the amending wasn't nearly enough. I did learn to dig, dig, dig in more organics AND, based on a comment in a rose book, add Perlite. You see, things would be fine in the cooler spring temps, but when the temps soared, that airless rocky clay just seemed to be choking the life out of the bushes. Plus, I later read that iron moves particularly slowly in heavy clay, and sure enough by late summer some of my bushes began to have typical lack-of-iron symptoms (chlorosis). My symptoms were poor sad growth, and some bushes would just die. I also had a disgusting grub problem, I would dig up the soil and there was grub after disgusting grub I mashed. Then I treated my garden with milky spore disease. All the amending, perlite, and milky spore disease seems to have improved things, but the improvements continue, and it IS back-breaking work. So I am wondering if you have lousy soil + you said your garden is at the base of a hill, so maybe you have water pooling there drowning/suffocating the roots. And the problem is really showing up as the temps rise?

I haven't had roses long either, but I think it is fairly easy to see where to prune in the spring. Wait to do it after your last frost which should be around March or April. It is a signal for your rose to start growing again so wait until you are sure it is safe. Now, when you look at your rose this spring you will see brown ends on the canes. That is dead wood, and you will cut all of that out. Make your first cut just below the brown wood into the green part of the cane. If you don't see any green cane then prune down to the soil. If the green cane is all white inside like an apple, it is good wood. If the inside is brown then you need to prune further down. Watch for dark areas on the green canes. That is canker and you need to prune below any canker you see. Once you have finished pruning seal all the cuts with something. I use regular white glue, but you can use carpenter's glue or nail polish. That will keep out borers which would otherwise lay their eggs inside the cut end of the cane. Feel free to stop by the rose forum for more advice. I post there quite often and everyone is very helpful.

It may well be too late to think of it, but if you want something lower-growing, some of the Polyanthas might be your answer for generosity of bloom and low stature. In our area, China Doll has been used and used and used because it matches those requirements. For a red, there's Mutterdag (Mother's Day) and Lady Reading. Salmon Pink Margo Koster, and all the rest of the Koster sports (do "Contains" KOSTER in a HMF search, or check Vintage's catalog). I'd use any of those guys before I'd try a Knockout -- Not because I'm a snob, but because Knockouts would be such horses, and because I don't want anything that mildews. In a more modern vein, if you want something truly low-growing, I'd use Kim Rupert's lovely 'Lauren' or 'International Herald Tribune' if I wanted poiple. For White, I might use Pope John Paul (or try the white China, 'Ducher.') For Yellow, gosh, how about Julia Child? For red, I'd really go back to Mother's Day. Jeri

I cut mine entirely out to the ground...BUT only 1/3 of the number of canes at one time...Say a rosebush has 9 basal canes, I entirely remove 3 of the oldest canes during early Spring. If canes are never removed they will get woody and unproductive in later years... Ok when I plant a new rose I let it grow for about 3 years without removing canes...(Unless one dies)...Then after that I remove 1/3 of the oldest canes each year...Our roses are mostly Shrub type roses with lots of canes...Double Ko, etc. I prune our Double Ko's down to 18" or higher each Spring also...Colder climates you might not have a choice because of winterkilled canes...