Also, remember that clematis are (at least in my experience) very temperamental, they die soon as look at them, and my best successes are ones that have been in the ground for some years - often doing very little for the first few years. This plant can produce dozens of flowers, each ranging up to 5 inches in diameter Plus, it’s beginner friendly. It’s one of the plants people use to make those gorgeous displays of arching flowers over their entryway. You might have to put up with 7 foot of leg and a cluster of flowers under the eaves, though. Clematis, also known as the Queen of Vines, is a vining plant that loves to climb. I think you should wait and see if it flowers at all this year, then prune hard next Feb. The whole point of pruning (I think) is to keep the stems shorter and neater, make them bushy from the base and influence flowering time. They reach for the sky and don't care if their nether regions look a bit threadbare because they would normally be clambering through a camouflaging understorey anyway. I think it's doing what clematis do, left to their own devices. If it's putting out healthy growth at the top then it must be OK. The sap released in the process can attract. A missed prune won't do much harm but if you do it now you will cut off any chance of flowers this year, unless it can crank a few out by Autumn. The slime, or flux, is likely to kill both the bark and any other plants (including grass) which they flow on to. (I wouldn't be!) I don't think you should prune it now, it should have been done in February. I don't think it will like being in a pot after a few years, although you do sound exceptionally good at looking after it. The plant is now seven feet high give or take a few inches. What is your opinion? I tend to discount the situation as it did so well in its second year - or could it be that the conditions were unusually mild last last year? There is good and flourishing new growth at the top of the plant - under the eaves of the porch. My wife wants to cut it right back to say six inches in order to encourage it. The container is watered daily and fed with Miracle Grow about once a month. We are in an urban situation less than half a mile from the sea. About a fifth of the leaves have withered and we had only one white flower! The container is on a North facing side of the house and is subject to wind. It shares a twelve inch cube stone container with a fern which is flourishing. It grew well up a wooden trellis and in its second year it bloomed as promised, exceedingly well. Two years ago we planted a Clematis Avalanche, the evergreen one with prolific white flowers.

Clematis slime flux