ST. PAUL (AP) - A new study says Minnesota's wine industry is growing up, but faces challenges.

The University of Minnesota Extension study says Minnesota's wine industry contributed $59 million to the state's economy and supported 3,250 employees in 2011 alone.  The industry barely existed before the introduction of cold-hardy grapes in the 1990s. And Minnesota's grape production continues to increase, particularly for the new Marquette red wine variety.

But the study also says Minnesota's wine industry is no longer a novelty in a state known for its frosty climate.

Extension researcher Brigid Tuck says sustaining its growth will require savvy marketing. Almost 63 percent of Minnesota wine is purchased at wineries, and most host special events such as weddings. She says agritourism endeavors such as wine trails also offer opportunities for boosting sales.