Those of us in the nursery business know that there are no shortcuts when it comes to growing plants. If we want to have good looking plants in June, they have to be planted well before that.
Having a garden with flowering perennials is no exception. Take our blueberries for example. If a customer buys the plant in May when it’s in bloom or has started to set berries- that plant will most likely lose the blossoms or berries when they transplant it, that’s the plant’s reaction to being pulled from a pot and placed into the ground, and all plants suffer from some degree of shock when they’re transplanted.
Spring is the time when we all have the urge to plant things. Our gardens are a blank canvas that we want to fill with colors. But if we really want to have a beautiful garden or landscape with perennial plants, the time to plan and plant is in the late fall. At that time of year, the ground is still warm and the soil can be worked much easier than in early spring. The plants are also entering their dormant stage for the winter, so the shock of transplanting them is reduced. Even though the plant is going dormant, the roots will settle in and start growing, and the plant will be ready to go in the spring.
Mulch around the plants (there’s plenty of leaves around in the fall) with a heavy layer, but keep it away from the plant’s stem. You can protect the stem from animal damage with a short section of split foam pipe insulation. It the spring, rake back the mulch and remove any stem protection when the weather starts to warm. Of course if the plant is one that usually dies back completely, the stem protection can be disregarded.
Purchasing and planting perennials in the fall will shorten the time it takes to get the full enjoyment from your plant investment that you are hoping for.
This link is an excellent guide to Planting Trees & Shrubs.