We have seen many plant samples from customers of less than health shrubs recently. Too many times the problem is older plants that haven’t been properly pruned to help the plant keep vigorous new growth coming. The plants get old and woody and lose their shape and density.
Flowering shrubs lose their natural shape if sheared at the top. You should only prune older branches and dead branches. This leaves room for the rest of the plant to grow. Flowering shrubs can be rejuvenated and kept young and healthy looking by removing 1/3 of the oldest stems in early Spring. If you do this three years in a row you will never lose a complete year of flowering; and after three years you have a healthy plant in place of the old one.
Evergreens with needles should not be left un-pruned when young. It’s best to lightly prune them every year when the new growth is finished sprouting in early summer. Light pruning will encourage the plant to grow bushier and keep the original shape you wanted. Trying to reduce the size of older needled evergreens will expose old wood which will not produce new growth and will look unattractive. Taxus yew is an exception to this rule as it can produce new growth from needleless wood and look good after a few years of growth.
Broadleaf evergreens don’t need much pruning. Some light pruning to keep the shape of the plant is all that is usually required. If holly, rhododendron, andromeda or azaleas get to be overgrown they can be cut back to leafless wood in early spring. In a few years they will look good, just like the taxus yew. You should remove spent flowers on your rhododendron to leave room for the new shoots to grow and develop.
For more information about how and when to prune trees and shrubs including Hydrangea, click here.