Pruning and Training Wall Shrubs
2008, Dorling Kindersley Limited
Pyracantha can be trained up a wall or a fence like a climber. New berries are formed at the base of stems made the previous year, so take care not to prune them off.
Certain shrubs, while not actual climbers, can be treated almost as if they were by growing them against fences, walls and trellises. Use the same pruning methods as for freestanding plants, but tie in stems during the summer in order to guide growth over the surface to be covered. At the same time, shorten any shoots that are growing away from the wall to make sure the shrub stays neat and narrow.
Pyracantha, cotoneaster, and ceanothus make excellent wall shrubs; all flower in spring at the base of stems made the previous year. Make sure that the wall is in good condition before fixing a trellis to it, as any repairs will be difficult once the plant is established. When pruning, take care not to cut back too hard into the old wood if you want blooms and berries. Shorten all new sideshoots in midsummer, leaving two to three leaves to encourage flower formation the following year, and to make any berries more visible.