As soon as their flowers fade, it’s time for azalea, rhododendron, chokecherry, lilac, weigela, forsythia, and viburnum pruning. These spring-blooming shrubs produce their flowers on the previous year’s growth. Pruning them too late in the season could mean removing next year’s developing flower buds. If you are unsure of when to prune a particular flowering shrub, a good rule of thumb is always to prune after flowering.

Whether you’re doing a viburnum pruning or a light shaping of your rhododendrons, proper pruning promotes well-branched shrubs with a denser growth habit.

Tips for spring-blooming shrub and viburnum pruning

You shouldn’t prune spring-blooming shrubs into round meatball shapes. Instead, start by removing any branches, and then selectively trim others, one-by-one, in order to maintain the shrub’s natural shape

  • Use a clean, sharp pair of pruners or a small pruning saw to make the mark. To the spritz of pruning disinfectant before you move to another plant.
  • The pruning requirements of spring-blooming shrubs are minimal because their natural growth habit requires very little maintenance.
  • Don’t remove more than one-third of the total plant height at any one time, and step back and carefully examine the plant after each mark.
  • Keep the shrub’s structure open by removing one or two of the larger branches each season. This also encourages new growth.

Viburnum pruning, and the pruning of other spring-blooming shrubs, but it does require a bit of finesse. With a light, yearly pruning that encourages their natural form, these plants will produce a plethora of beautiful blooms every spring.

Pruning can benefit landscape plants by maintaining size, promoting flowering, removing and focusing growth on younger or more vigorous stems and helping to control insect .  However, timing can be on flowering shrubs, especially spring blooming shrubs. 

For these reasons, shrubs which bloom prior to mid-June should be pruned shortly after flowering each year to preserve flower buds.  By pruning these shrubs now, the new growth that results will have time to fully mature this growing season and develop the flower buds needed to bloom next spring.  In some cases, this newer more vigorous growth, combined with additional sunlight to inner branches can actually enhance the flowering display of the coming spring. 

Generally, spring flowering shrubs are pruned using the renewal method.  In this technique, about 1/3 of the largest, oldest stems are removed at ground level.  This focuses growth on the younger, more vigorous stems.  It also opens up the interior of the plant for increase air flow, which helps control pathogens, and increases sunlight, which helps develop a array of interior growth.

Now that you are armed with good information on when to prune spring flowering shrubs, have confidence and get out there pruning.  Remember, it will always grow back and practice makes perfect.

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