Throw Those Power Shears Away! Hand Pruning Is The Way To Go
Hand pruning by an experienced horticulturist can greatly improve the health of your shrubs and small trees. Shearing plants with power tools is not only time consuming, but can stress plants, making them more suseptable to disease and attacks from insects and mites. Proper hand pruning combines a mixture of directional, heading and thinning cuts. These cuts control height and width and also allow air and light to penetrate into the plant interior. Air circulation and sunlight help to dry the plant quickly after rain or irrigation. This is critical because constant moisture can promote fungal disease.
In addition to disease vulnerabilty, sheared plants are more suseptable to insect and mite outbreaks. Azalea, boxwood and hollies are among these. Sheared azaleas are frequently attacked by lace bugs and mites. Shearing your boxwoods will likly lead to a mite outbreak. Sheared hollies are a magnet for scale insects.
Why does shearing a plant make it vulnerable to attack? Besides stressing the plant, sheared plants develop a tight, shady shell which creates an environment that is hostile to beneficial predators. These are the "good bugs" that keep the "bad bugs" under control. Beneficial predators like lady bugs and lace wings prefer to operate on a plant that is more loose and open.
Shearing formal hedges with power equipment is a sometimes necessary evil on formal landscapes. In this situation, small, fist sized holes should be pruned into the hedge with hand clippers. Small holes should also be made in individually sheared plants.
You should always be able to just barely see through a correctly pruned shrub.