Clematis is the classic companion to roses — the two climb together naturally, clematis threading through rose canes to add colour before, during, and after the main rose flush. There are three pruning groups: Group 1 (spring-flowering, prune after bloom), Group 2 (large-flowered hybrids, light prune in early spring), and Group 3 (late-flowering viticella types, cut hard to 12 inches in late winter). For mixed plantings with roses, Group 2 and 3 varieties are most useful.
The cardinal rule is 'cool roots, warm top': mulch deeply at the base and plant with the crown 2–3 inches below soil level to protect the growing point. Clematis wilt can strike suddenly, collapsing a stem overnight — cut back to healthy tissue and the plant almost always recovers from the protected crown.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.