Last year I planted a row of mostly Allegany Viburnum with a couple Davidii and Prague for a privacy hedge. The Prague and Davidii have lost all their leaves over the winter. I thought they would be evergreen. The Allegany have a few shriveled up leaves. The hedge row is in full sun and exposure. Is this the best I can expect from these plants? I thought they would provide more privacy and be more evergreen. Thinking about removing some and replacing with hollies and/or little Gem Mag.