I put in a young plant of this last summer, bought at an RHS show I think. It had some new growth by the autumn, but not exactly vigorous. Sat there over winter with small shoots on its tips but these now seem papery. Buddleja weeds in the garden, and 'Black Knight' too, are growing vigorously. Is B. colvilei slow to start or more tender than I thought in an open position? It is not in a frost pocket.