"However, some lavender plants can bloom earlier in the season than others, so the exact timing of pruning will depend on the variety that you are growing." Climbing hydrangeaClimbing hydrangeas are the only type of hydrangea suited for summer pruning. Rambling rosesOnly rambling roses should be pruned in summer, and that should be done after flowering, Barker advises. It is advised to not prune roses if rain is expected (Image: Getty Images)For young rambling roses, cut stems back by about 40cm and remove any dead or damaged growth. Barker recommends not pruning roses if rain is expected, as this can increase the risk of fungal infection at the cut sites.