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When to Prune Shrubs in Minnesota

By Sharon Sweeny ; Updated September 21, 2017
Azaleas bloom during the month of April in Minnesota.

Pruning shrubs in Minnesota is similar to pruning in any other US Department of Agriculture hardiness zone. Wherever your garden is located, the time to prune is determined not by what month it is, but by the growing and blooming habits of the shrub in question. Regardless of the species or variety of your shrubs, determining the best time to prune them depends on when they bloom.

Early-Spring-Blooming

Nearly all shrubs that bloom in very early spring do so on wood grown the previous summer. Therefore, the best time to prune shrubs like azaleas and rhododendrons in Minnesota or elsewhere is immediately after they finish blooming. If you prune them later in the season, you cut off their newly forming flower buds, eliminating flowers the following year. Depending on the species and variety of the shrub, prune them during April or early May in Minnesota.

Late-Spring-Blooming

Shrubs that bloom later in spring, such as lilac, bridal's wreath and forsythia, should also be pruned immediately after they finish blooming. Very few shrubs that bloom later in spring flower on the current years' wood. Accordingly, prune them right after their flowers fade, unless you wish to cultivate and harvest their fruits. In that case, prune them in late winter, but only to remove dead or diseased branches, and to remove older growth making room for newer, more fruitful branches to develop.

Summer-Blooming

Although only a few varieties of shrubs bloom in summer, such as roses, hibiscus or hydrangeas, those that do bloom in summer produce their flowers on branches that grew during the current growing season. These shrubs are best pruned in late winter or very early spring. Ensure that you prune them before the sap begins to rise and before the buds begin to open.

Pruning Techniques

Make the pruning cut just beyond the point where the branch grows out of its originating branch, also called the crotch of the branch. There is a slightly raised ridge encircling the branch near the crotch. Make the pruning cut just beyond that ridge. Pruning cuts made this way heal faster and do not require sealing with products specifically designed to seal pruning wounds.

Remove all dead or diseased branches, cutting back to live, healthy wood. Also remove one of any pair of branches that are crossing or growing too close together; remove the weaker of the two.

Whether you are pruning in early spring, summer or fall, never remove more than one-third of the shrub's branches, to ensure the remaining branches can manufacture enough food to keep the shrub alive.

Some shrubs are prolific growers, sending up "suckers" around their bases. These suckers can -- and should -- be cut off at ground level any time during the growing season. They sap energy from the shrub and will reduce the number of flowers the following year.

 

About the Author

 

Sharon Sweeny has a college degree in general studies and worked as an administrative and legal assistant for 20 years before becoming a professional writer in 2008. She specializes in writing about home improvement, self-sufficient lifestyles and gardening.