[3] The exact origins of the boysenberry are unclear, but the most definite records trace the plant as it is known today back to grower Rudolph Boysen, who obtained the dewberry–loganberry parent from the farm of John Lubben.

[5][6] In the late 1920s, George M. Darrow of the United States Department of Agriculture began tracking down reports of a large, reddish-purple berry that had been grown on Boysen's farm in Anaheim, California.

Undaunted by this news, Darrow and Knott headed out to Boysen's old farm, on which they found several frail vines surviving in a field choked with weeds.

The number dipped during World War II but peaked again in the 1950s at about 2,400 acres (970 ha), to the point where boysenberry crops exceeded those of the (previously) more common raspberry and blackberry.

[3] By the 1960s, the boysenberry began to fall out of favor due to a combination of being difficult to cultivate, susceptible to fungal diseases in coastal growing areas, and too soft and delicate to easily ship without damage, as well as having a short season of availability compared with newer cultivars.