Ornamental grasses and many ground-covers should be pruned annually before new growth appears in the spring. Perennial vines need to be pruned periodically to control their aggressive growth, but care needs to be taken to limit removing flower buds.
Pruning Trees and Shrubs
Deciduous trees (trees that lose their leaves once per year) – Ideally pruning should be done while the tree is dormant over the winter and it is recommended to wait until late-winter such as February or March.
Evergreen trees (trees that maintain their leaves or needles year-round) – Depending on the species, most pruning should be done between late-winter through mid-June.
Any ornamental tree or landscape shrub that flowers after June 15th should be pruned in early spring, preferably before April 1st
Any ornamental tree or landscape shrub that flowers prior to June 1st should be pruned immediately after the spring flowering to avoid removal of the buds for the next growing season.
Continuous blooming shrubs, ones that flower throughout the growing season (spring, summer and fall) can be pruned throughout the year but avoid pruning just prior to winter as new stimulated plant growth can become susceptible to cold weather damage.
Most non-flowering shrubs can be lightly pruned at any time during the growing season but it is best to wait until the shrub goes into dormancy, during the winter, before doing any major pruning or reshaping.