'Rooguchi' is unlike most clematis in one key way: it does not cling. A Pruning Group 3 herbaceous hybrid, it dies back to the ground each winter and re-emerges in spring as a loose, arching shrub that sprawls beautifully through neighbouring plants. The flowers are nodding bells of deep indigo-blue, slightly twisted at the tips, and they appear continuously from June through October — among the longest bloom seasons of any perennial in the garden.
Because it has no self-supporting mechanism, the best way to grow 'Rooguchi' is to let it thread through the lower canes of a rose or shrub, or to give it a low peony cage early in the season. In Zone 6b it is completely reliable: cut everything back to 4–6 inches in late winter before the new crowns emerge, top-dress with compost, and it will return with vigour every year.
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.