He now works with propagator Hargreaves Plants which has exclusive UK rights.
Some 60 nurseries are now conducting trials. A primocane, it can produce two crops a year in May/June and from August.
Polka has been making £8-£9 at wholesale, a third more than traditional varieties.
Said Stubbins: “Polka has shown it can follow on from Tulameen and Glen Ample.”
Hargreaves Plants expect to double the amount of canes available next year to more than a million.