Learning how to grow clematis in pots isn't too difficult, especially as you can keep your eye on it when it's in a container. But if problems occur they are generally connected with careless pruning, especially at the wrong time of year. If you remove the part of the plant that produces flowers naturally this can prevent flowering.
'There could be several reasons why a clematis in a pot isn't thriving,' says Tony O'Neill, gardening expert and author at Simplify Gardening. 'One possibility is that the pot is too shallow, restricting root growth. Another factor could be inadequate sunlight, as clematis plants require at least six hours of sunlight a day. Additionally, poor-quality or poorly-draining soil, improper watering, and lack of support for the plant's climbing habit could all contribute to a struggling clematis.'