I have 2 clematis that are not growing. One (Rituaal) would start, then the tiny green growth would die off. This happened 3 times already this year, so I took it out of the pot, washed off the soil and discovered that the top of fibrous little pot it was originally grown in was strangling the crown. Small roots in the center of the root mass were growing in a circle and in the center of the fibrous collar and the circle of roots was mass of perlite. I gently removed the fibrous collar, straighten the roots the best I could without too much breakage, and got rid of the mass of perlite. I'm sure this clematis was already pot bound before it was planted into the larger pot it was shipped in. I did not get this clematis from a reputable source.

I discovered, after barerooting, that the other clematis (Maria Cornelia) was suffering from rotting roots because the soil was saturated. I don't know if the nursery I got if from used soil that contained moisture-retention pellets, or whatever those are called, or if I had accidentally bought potting soil with those pellets. I had to pluck of the swollen pellets off little root hairs. If it ends up being that the nursery used the pellets, I doubt I'll buy from them again. If I do, I'll have to bareroot it before planting.

Both clematis are repotted now, and we'll see how they do. I'm sure Rituaal will grow, not sure about Maria Cornelia.