Can perennials be planted in containers?
Perennials can be planted in containers. The problem arises if the container is too small. With small containers, the sun will thaw out the soil very quickly in the early spring, sometimes before the ground is thawed out. What this does is it encourages the perennial to think it is summer too early and makes it want to start growing too early. The danger lies in when we get a hard frost mid-spring and the perennial is actively growing. This can be really hard on the plant. Therefore, if someone wants to put perennials in a container, it is no problem as long as the container is large enough that it will not thaw out much before the natural ground will thaw in the spring.
