We recently removed the thermo-blankets from our perennials that were in storage for the winter season and discovered that the roses still showed plenty of life. They also showed signs of death as well. This is why trimming the rose bushes is so important now. The dead growth is your indicator as to how far the trimming needs to be. Generally, cut off all dead growth and even some good growth so that what you are left with is thick, stubby stems that are about six inches long. You only need to have five to seven good stems pointing in all directions. Cut everything else off.
All of the other perennials need to be watered and the areas around them raked and cleaned up. So many of them look dead, with no hope for survival but they will surprise you in the end. That is because most of the old growth really is dead and the new growth will appear from underground. This is so true with items such as the hosta, peony, daylilies, perennial hibiscus (don't expect signs of life on hibiscus until late May) and hardy garden mums. On the other hand, ground covers are looking good and green already as well as a few other perennial plants that actually look as though they just kept on growing all winter long.
Once we have a few rainy days and see more evidence of life, the top-dressing of cow or mushroom manure, as well as a small handful of granulated slow-release fertilizer would be beneficial. Also, bone meal is a great and safe form of an organic fertilizer that many gardeners use as the season begins. It is important not to get any of these fertilizers directly on the center of your plants as they can damage, or burn any new growth that is about to come. If you think that you may have gotten a little heavy-handed with anything, water immediately. I heard this on television the other day, "The solution to pollution is dilution."