Rose achenes are programmed to survive a winter before they germinate. I haven't heard of anyone doing other that cold stratification, Malcolm Manners site - find it with google " achenes Malcolm Manners", and that site links to several propagation resources. I suggest the enzymatic treatment with septic tank compound, stratify them for another 6 weeks, try to germinate them, and try sowing some without stratifying, and report back to us. Thanks. Paul Mozarowski.