No worries, your peonies are just growing roots underground and settling in before any top growth. It may take them several years to grow to blooming size but peonies  are very long lived perennials so you will enjoy them for decades. One reminder is to not plant your peonies too deep. The growth knobs or eye of the peony tuber should be just barely below the surface of the soil. Even using a mulch on top of the peony growth point can prevent it from blooming as they can be covered with too much soil or mulch. Cut back the foliage in the fall once it yellows and give a spring feeding of a slow release plant food like Osmocote and you should enjoy peonies in a year or two. Keep growing, Marianne Binetti