Hi there,

All my clems are in containers. Each container is at least 18" diameter... but I couldn't tell you how deep they are without going out there with a ruler. I'll post a pic at the end of this post so you can see that they look like pretty standard sized pots.

I'm in a different zone than you - we don't get hard freezes. I don't do anything with mine over the winter, so I'm afraid I can't help you there.

The clems are all in the big terra cotta colored pots.

{{gwi:606007}}

The general rule of thumb is a plant should be 2 zones lower than your zone for it to survive over winter in a pot. Elsa Spath is rated as zone 4. I've heard people wrapping pots with bubble wrap or putting them in the garage for the winter, but survival is still questionable. I'm not sure if that is from frigid temps or because people either neglect to water or over-water causing the roots to rot. Freeze/thaw cycles can also cause problems, so keeping the pot shaded will be beneficial.

Back to the bubble wrap. Some people don't like using it because of the green house effect it creates if the plant is in a sunny position. Wrapping the bubble-wrapped pot with burlap or something similar might help.

Do you have available garden space? If you do, you could purchase a large plastic liner pot, then build the decorative pot around it. Before winter, bury the potted clematis in the ground leaving an inch or two of the pot exposed above ground; cover with mulch. Before covering it, make sure the soil slopes away from the pot. I haven't tried this with clematis yet, but I've seen several local landscape nurseries do it. Actually, I have even seen pots set on a gravel path and cover with 2 feet of mulch. Regardless, proper drainage is key.

As far as the pot size is concerned, I read that while it's good to be larger, it still has to be a manageable size because at some point you will need to lift the clematis from the pot, root prune a little, and replace most of the old soil with fresh.