Clay and roses don't really work together. Roses need good drainage. The first rule of planting a rose is to dig the hole, then fill it with water [before you put the rose in] to see how long it take for the water to drain away. The better the drainage, the happier the rose.
When we moved here and started digging the garden beds, I double dug the bed I wanted to put roses in. Double digging is where you remove the top soil, then dig down another foot or so and loosen everything up and amend the soil, yada, yada, yada.
The trouble was that we were digging down into clay. My dad came over, took one look at the hole and said, 'You've dug a swimming pool. That water is never going to drain.' He was right, dammit. It rained that night and that water stayed in there for freaking ever.
We tried roses on the terraces, but they didn't like that either. Then we transplanted some old roses that Eric rescued from a job and they did fine. And we got some rugosas and they've done fine, too. Roses can do just fine here. We just had to find tougher roses.
And don't get me started on those blasted multiflora roses that they wild planted in the midwest to feed the birds. They grow here, too.
Last week, Eric and I went to war against a giant multiflora that turned out to be a linked community of them an acre across, with canes 80 feet high and thorns the length of your arm. They were smart, too and fought back. I have verily been wounded by one! The blood! Oh, the horror!
I might be exaggerating a little.
But only a little.
The roses were linked. There were about 8 of them. The canes were only 15 feet or so high and the thorns were the big scary rose bush size. The rest of the story is absolutely true.