What do the experts recommend regarding time(s) to prune the native roses, Rosa nutkana and Rosa gymnocarpa? I am interested in controlling their growth without losing bloom and/or rose hips. Do either or both of them bloom on second year wood?
Peter McHoy’s A Practical Guide to Pruning says that the pruning method would follow that of vigorous species roses, which produce flowers on old wood. He says to remove any dead wood in early spring (similar to ‘late winter’).
The Royal Horticultural Society A to Z Encyclopedia of Garden Plants (edited by Christopher Brickell, Dorling Kindersley, 1996) says to prune species roses as needed only, cutting out one fifth to one fourth of the oldest stems. A Pacific Northwest native wildlife gardening source on the web recommends only pruning out dead wood, and otherwise leaving it be.
Since Rosa gymnocarpa is also once-flowering, it should be pruned–if you need to prune it at all–just after flowering.
The following are general guides on rose pruning in the Northwest, from the Seattle Rose Society and Roses for the Pacific Northwest.