In 1843, Bull began the deliberate process of breeding a grape that could thrive in the cold New England climate. By 1849, having planted 22,000 seedlings, he had created a large, sweet variety from a native species. By 1853, the grapes were for sale, but within several years, competing growers had begun raising their own crops of Concord grapes, purchased from Bull for $5 per vine. Bull saw little profit from the strain after the initial sales.
Ephraim Bull was elected to the Massachusetts House of Representatives in 1855. In 1893, after a fall, he ended up in the Concord Home for the Aged. He died in 1895. His epitaph reads, He Sowed Others Reaped.