The shrub rose rosa rugosa puts out a long season of flowers once it gets going, flowering all summer and into the fall. Rosa rugosa grows in U.S. Department of Agriculture hardiness zones 4 to 7, producing white or pink flowers. This plant benefits from annual pruning to keep it healthy and to control the size. A rosa rugosa that goes without being pruned can reach a maximum height of 7 feet with an equivalent width.
Rosa rugosa plants should be pruned while the rose canes are still dormant. Prune in late winter or early spring, after heavy frosts have passed. When pruning at this time, rose plants won't have leafed out for the season, making it easier to identify old or damaged growth that can be tricky to see when the canes get shaded by leaves later in the season.
When cutting back these plants, use the rejuvenation technique, which removes the oldest, most woody canes. This spurs growth. Choose one-third of the oldest canes -- these will be thicker at the bottom and more woody, with less green tissue -- and chop them down at the base, using pruners. Once you've done this, cut back long branches to keep the rosa rugosa's size in check.
Rejuvenation pruning prevents rose shrubs from getting too crowded and increases air circulation. Shrubs with greater air circulation are less likely to contract bacterial or fungal diseases. These roses can look overgrown or bushy if not pruned regularly, so annual trimming helps give the rosa rugosa a manicured look.
The rosa rugosa twigs and stems are covered with small thorns that can make pruning a challenge. To protect yourself from injury, wear gardening gloves, long-sleeved shirts and long trousers to shield your hands, arms and legs.