How to Grow Clematis in Containers in the Frozen North
Yes, you can! Even in the Frozen North, it is possible to grow clematis in containers, as long as you pay attention to a few important things. When you come right down to it, we grow Betty Corning, one of our largest clematis, in a container of sorts. And with the ever increasing number of clematis that are bred for container use, the options are nearly limitless. Follow these four steps and enjoy your container clematis!
1. Choosing the containerThere are two important considerations in selecting a container for your clematis. The first is the size. "Standard" recommendations call for containers for small clematis that are a minimum of 18 inches in diameter. (Small clematis are 6 feet tall or less.) Here in the Frozen North, we think 24 inches should be the minimum. If your container is less than that, we recommend extra protection in the winter. (See "mulching", p4.) And, of course, the larger the clematis is, the larger the container should be!
The second thing to consider is the material from which the container is made. Some materials (say, cement!) are heavier than others (like the resins). This is important if you plan to move the container once it is planted.
The material also affects the container's ability to stand up to harsh winter weather. Ceramic or terra cotta containers will not stand freezing temperatures without breaking. These containers, and the plants they contain, need to be moved to a spot where they will stay cold during the winter (so the plants don't try to grow) but where the soil won't freeze and break the containers. Wooden and some resin containers WILL stand freezing temperatures and can be left where they are.