Answer: Ninebark, Physocarpus opulifolius, is hardy into zone 2, so it should be hardy in your area. It is a deciduous shrub so it normally loses its leaves for the winter; the bark may also peel, this is one of its distinguishing characteristics. The plant would come out of dormancy naturally as the season progresses. I would be somewhat concerned that they have been under teepees, if for some reason excess heat could have built up inside the teepees and interfered with their normal protective mechanism of dormancy. For winter protection, a plant that is hardy in your area should need only some mulch at the base. In a windy location, some wind protection could also be beneficial. Snow is an excellent insulator, so even if the tops have died back the roots should be able to regenerate the shrubs this season. A newly planted shrub might experience some winterkill, especially if allowed to dry out during the fall prior to freezing temperatures. To check if they are alive, begin at the tip of a branch and work your way downward, checking inside for hints of green. If there is no green and the twig seems like a dry and dead branch and snaps right off, then that wood is dead. Remove any dead wood. You should see new growth from buds that swell later this spring. Then also wait until early to mid summer for signs of new growth from the ground.
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