I live in Michigan and in my neighborhood the soil is slightly alkaline 7.3 (Michigan soil varies all over the state). Rosa multiflora is a very happy weed around here, so I think it's alkaline tolerance may be pretty good, although there may be other factors involved since soil is so complex. I actually prefer roses grafted on multiflora, and get most of my roses from Pickering since most of their roses are grafted on multiflora stock with a few exceptions. Every rose I've planted from them has always taken right off, I've never had a failure. I've had very few own root roses do well for me with the exception of Alika and James Mason. Those roses are incredible, but give them a huge amount of room, they sucker and don't play nice with other plants. Alika is growing on really crappy, stony, gritty 7.3 soil. It took about three years to establish. While establishing it looked like a spindly, vase-shaped plant and I came close to shovel pruning it, but in the fourth year it exploded sending out suckers everywhere. It has now grown into a briar clump of about 6 x 12, and would be bigger if the mower didn't stop it. James Mason is establishing a briar clump also and he is a grandchild of Alika thru Scharlachglut.