I have three container grown Clematis (names not known) that did not do at all well last year. I would like to replace some of the soil and generally get them to perform better than before. I believe they are mid/late bloomers. They are at present looking very tatty, tall (4-6 feet high) and brown. Could someone please advise the best time and method to prune and also the best time to take out old soil and replace with new, to replace nutrients please?
Also, may I ask how much and when to water, as I feel this where I failed last year.