Peonies are a northern perennial gardener’s standby.   They are tough, hardy, drought-tolerant, and not to mention outstandingly beautiful on the plant and as fresh cut flowers.  Can you tell I love this perennial?? Being a spring flowering perennial, peonies are classified as early, mid, and late spring bloomers.   But sometimes their flowers don’t show up, so let’s talk about the different types of Peonies, and then explore eight reasons why Peonies don’t bloom.  While we’re at it, we’ll touch on how and when to plant a Peony. Five Different Types of Peonies Peonies are divided into five distinct groups:  Garden Peonies, Tree Peonies, ITOH/Intersectional Peonies, Fernleaf Peonies, and Woodland Peonies. Here they are in more detail: Garden Peonies Garden peonies, also known as herbaceous peonies, have a rounded, shrub-like shape.  They are very floriferous with a wide variety of flower shapes.  They are vigorous, very hardy, and many varieties are fragrant.  Garden Peonies are herbaceous perennials, which means that they grow fresh from the ground each spring. Sometimes they need wire support to stand straight under the weight of their heavy blossoms. Garden Peonies range in hardiness from zone 3-8. Tree Peonies  Tree peonies have a shrub or tree-like shape, depending on the plant hardiness zone they are growing in. They can grow over 4 feet tall in warmer climates like the lower mainland of British Columbia and southern Ontario, but they stay shorter in cooler plant hardiness zones. Many Tree Peonies sport huge semi-double blossoms in unique colour combinations