Springtime pruning of deciduous shrubs

Shrubs and trees can ben­e­fit from peri­odic prun­ing for a vari­ety of rea­sons. Some­times the plant has out­grown its place in the land­scape, or there are dead branches that need to be removed. Other times, shrubs and trees need prun­ing to main­tain their shape or to pro­mote new growth. While we rec­om­mend that home­own­ers use a Cer­ti­fied Arborist to prune large trees, the home­owner gen­er­ally can safely prune shrubs.

Late win­ter or early spring, before the plants have started their sea­sonal growth, is gen­er­ally the best time to do most of your prun­ing. At this time of year a decid­u­ous plant is eas­ier to prune, since there are no leaves and you can bet­ter see the plant’s struc­ture. How­ever, even if you miss this win­dow, most plants can be suc­cess­fully pruned at other times of the year.

The prun­ing tools you need will depend on the size of the plants that need prun­ing. Bypass hand pruners can be used to cut branches up to about ¾” diam­e­ter. They have two sharp blades that cross each other like scis­sors do when closed and give a cleaner cut than anvil pruners, which have only one cut­ting blade. Bypass lop­pers are sim­i­lar to bypass pruners, but they have long han­dles that some­times are extend­able. Lop­pers can reach fur­ther than pruners and can cut up to 1½” branches. For thicker branches you will need a prun­ing saw. A wide vari­ety of hand saws are avail­able, includ­ing fold­ing saws, which are easy to store and carry.

While a warm day in late win­ter or early spring is the ideal time to do most of your prun­ing, dead branches that cre­ate a safety haz­ard should be removed imme­di­ately. Also, shrubs that bloom in the spring or early sum­mer should be pruned shortly after they flower, since the buds are gen­er­ally formed on the prior year’s growth. Plants that flower in mid-summer or later gen­er­ally can be pruned early in the year, since their buds are formed on the cur­rent year’s growth. If you are unsure about whether your shrub should be pruned before or after bloom­ing, first, cor­rectly iden­tify the plant, and then check with your local gar­den cen­ter, online nurs­ery, or the Delaware County Mas­ter Gardener’s Helpline at 740/833‑2030.

There are two gen­eral types of prun­ing cuts; 1) head­ing and 2) thinning.

Head­ing or head­ing back removes only part of the branch. The cut should be made about ¼” above a bud to pro­mote new growth. Unless you are trim­ming a for­mal hedge, you should avoid “top­ping” a shrub with a hedge trim­mer, since it destroys the plant’s nat­ural shape. Shear­ing with a hedge trim­mer also increases branch­ing on a plant’s exte­rior, shad­ing the inte­rior and elim­i­nat­ing new growth in that sec­tion of the shrub.

Thin­ning removes an entire shoot or branch at its point of ori­gin at the ground or on a larger branch. Thin­ning the cen­ter of a shrub will enable light to reach its cen­ter and pro­mote new growth. Also, the increased air cir­cu­la­tion can improve the plant’s health by dis­cour­ag­ing pests and dis­eases. Cross­ing branches should also be removed.

When multi-stemmed decid­u­ous shrubs have been neglected or incor­rectly pruned, the plant can be renewed by remov­ing the older stems at ground level. Head­ing cuts that trim back the stems by 1/3 to ½ and are made slightly above a bud will stim­u­late branch­ing. The entire renewal process can take up to three years, if it is done slowly and cor­rectly. In gen­eral, never remove more than 1/3rd of a shrub or tree when prun­ing. How­ever, if a fast-growing multi-stemmed shrub has been neglected for sev­eral years and becomes a thick tan­gle of branches, the only to reju­ve­nate the plant may be to cut it back to the ground. New shoots will emerge to form a new bush. These shoots will need to be thinned and the plant will need to be pruned on a reg­u­lar basis to form an attrac­tive bush.

If you are in the process of plan­ning a new foun­da­tion plant­ing bed or an addi­tion to your land­scape, your choice of plants can deter­mine the amount of maintenance-related prun­ing that is required. Slow-growing shrubs need less pruning.

They also take longer to fill in the land­scape. There­fore, you might want to plant larger spec­i­mens. Your local gar­den cen­ter can give you advice on prun­ing and plant growth habits.

Pick a date in late win­ter or early spring and mark it on your cal­en­dar to remind your­self when it’s time for spring prun­ing. Remem­ber to enjoy the col­or­ful blos­soms on spring bloom­ing shrubs, such as for­sythia and lilac, and wait to prune them shortly after the flow­ers fade. Prune your shrubs or trees so that they main­tain their nat­ural shape. If you develop an annual prun­ing rou­tine, your gar­den will look much neater, and the job will be more manageable.

Nancy F. Traub is an OSU Exten­sion Mas­ter Gar­dener volunteer.

Posted by Master Gardener on Mar 15 2013. You can follow any responses to this entry through the RSS Feed. Comments can be made below.