It all depends on the type, age and size of your hedge and what you are hoping to achieve. To encourage growth hedges should be trimmed during spring and right up till the of summer and high growth seasons. Large leaves that are tough do well to be pruned with secateurs. Start with hand shears to remove any dead branches and to thin out the top of your shrub. It is best to remove about one- fourth of the old growth each year and cut them off from the ground. Trim hedges wider at the bottom and less often and Prune less of the shrub at the top more frequently. Regular trimming and pruning and will help keep your garden looking great and healthy.