Anna, I have it planted in a rock garden and this happened by mistake. I was traveling and did not have time to plant and I put it it against the tree before I went on my business trip. I was so busy I forgot I had put it under the tree.
You should have seen my face when I was walking around the garden wondering where the fragrance was coming from and realized it had planted it self in a mostly rock area and climbed the tree. I just took some homemade compost and shoveled on top of the pot. It has been there now for 3 years. I was afraid to dig it out and try to get it out of the pot.
I got 13 Clematis from a independent seller for 3.00 a piece so it was easy for me to forget what I had with my business travel at a high time.
I would love to move it closer to the house but I am afraid to move.