When the tag says to fertilize perennials & shrubs in the spring, what is the suggested fertilizer?

There are a couple of different fertilizers you could use for your perennials and shrubs. The Art Knapp's Tree, Shrub and Hedge food (18-4-8) is good for things such as evergreen shrubs. The Art Knapp's flower and vegetable (8-20-20) is good for all of your perennials and flowering shrubs. Both of these fertilizers are slow release, granular application. If you wanted to use a water soluble product that should be applied every 2 weeks for best results, I would recommend Plant Prod 30-10-10 for your evergreens and Art Knapp's 12--36-12 for your flowers, (annual and perennial) and other flowering shrubs.