A year ago, I came across a rose garden with beautifully defined borders and pea gravel ground cover and couldn't get it out of my head. The pea gravel ground cover attracted me because it seems like a good way to keep weeds down and keep the rose garden low maintenance. I was advised against it by a reliable source, but I don't remember why.
I researched rose gardens and gravel, but didn't find anyone who has actually done this. Out of sheer desperation I asked google "can I cover rose garden with gravel" and it led me to GardenKnowHow and this bit of information:
Gravel Mulch For Roses
I use ¾ inch gravel mulch called Colorado Rose Stone around nearly all of my rose bushes. The gravel mulch is knocked by some as they say it will make the root zone too hot and kill off the plant of bush. I have not found that to be the case in my climate here in Northern Colorado at all.
I like the gravel as I can fertilize all of my rose bushes and plants by sprinkling the fertilizer over the gravel around the bushes, rock the gravel back and forth a bit with a hard tooth rake and then water it in well. I can add some organic matter as well by sprinkling some bagged Top Dressing over the gravel and water it down in well. The zone under my gravel is then a very good soils zone and the organics do their thing to mix further down into the actual root zone.
Well, that's good enough for me! I cleared the area, added the weed barrier (harder than it looks) and tossed what pea gravel I had around, on top.