My Marquette are 4 years old now, last winter we had minus 25 for a few days, lost two weak plants and some minor stem damage but the rest of the plants are great. They waited till a day after our usual last frost date to bud out so didn’t have any frost damage. The last 2 years I’ve been buying my Marquette grapes from a vineyard south of Madison the wine is very good although they start picking when the acid is still too high. This year with my grapes I’ll wait till the acid begins to drop before I pick.