As we head into winter and our planting winds down, it's appropriate that our garden efforts turn to cleanup and pruning. Many consider pruning a last resort, when a particular shrub or tree is in real trouble but in fact regular pruning can be a most beneficial treatment. This "kindest cut" is an important aspect of plant health. As deciduous trees, especially fruiting trees, go dormant that is the time to clear out any tangled or crossing branches to create more interior space. This holds true for trees such as dogwoods and maples. Deciduous shrubs such as hydrangeas benefit from being pruned back after they lose their leaves. Hydrangeas can easily become overgrown or leggy so a hard pruning can benefit their overall health. Other shrubs such as sambucus (elderberry) benefit from a winter pruning in much the same way.
Sometimes pruning is simply cleaning up. For certain clematis that sprout on new wood, once they lose their leaves you can cut them back to the ground. Make sure they aren't varieties that sprout on old wood, like Clematis tangutica. Even evergreen shrubs benefit from yearly pruning. Large shrubs like camellias can become too dense and need thinning out from time to time. Without proper circulation and access to light, some of these evergreen shrubs may be more prone to thrips. Anyone that's dealt with thrips knows how destructive they can ne.
It isn't just trees and shrubs that benefit from a haircut. Certain perennials also like regular pruning. Larger perennials or sub-shrubs like lavender, rosemary, salvia, caryopteris and heliotrope benefit from pruning. They can easily get woody; the pruning stimulates healthier new growth. Always try to prune when the plant is not flowering. Certain grasses also benefit from a winter haircut, most notably pennisetums. Cut them right down to the base. Come spring they'll flush out new growth and look like you expect them to do.
If you have any questions at all about pruning, consult your nearest nursery professional.