Three reasons you want to prune spring-flowering shrubs in June:
1. Most importantly, the shrubs will bloom next spring. It is so disappointing to have spotty little flowers or no flowers at all. This is created usually when the enthusiastic gardener is tidying up in fall and gives the shrubs a reshaping — thus cutting off all next spring’s flower buds. Flowering shrubs set next year’s blooms by the end of June. That is why now is the time to prune.
2. Reshape the plant into a “responsible” size. There is nothing worse than spending the rest of the year battling back the trailing branches each time you walk the sidewalk. If they outgrow their selected spot, they will rub against the house or shade your other landscape plants.
3. Preserve the shrub’s glory so it continues to produce blooms all over the plant instead of just at the spindly tops.
Spring-flowering shrubs provide a colorful backdrop for the first bulbs, and their blooms persist through the spring until the perennials burst forth with their summer color.
In North Central Washington, we can grow a number of colorful, fragrant shrubs because our climate provides winter cooling and warm, moderately dry springs.
Breaking into vibrant yellow bloom when the soil temperature reaches 50 degrees, Forsythia is our harbinger of spring. This is followed by the fragrant four: Wisteria, Viburnum, lilac and mock orange. Spring ends with the pinks of the Wigelia and Rhododendron.
Now is the time to maintain these landscape assets. If not pruned at the right time nor at all, these shrubs become gangly, bloom poorly and spread profusely to become a common, everyday garden thug!
What is the shrub’s natural size? Most flowing shrubs naturally grow to about 10 feet tall. If you want it to be a 5-foot ball, you will be spending the rest of your life whittling away at it. Perhaps you have the wrong plant in the wrong place.
People always tell me that they are hesitant to make big cuts because they are afraid it will hurt the plant. Don’t worry — plants lack feelings and won’t hold any pruning against you.
Be sure to use the proper tool. If the branch is more than 1/2-inch wide, don’t use a pruner; use a lopper. If the branch is more than 1-inch wide, use a handsaw to ensure a clean cut.
Start pruning by removing the long, extended branches that whip you in the face as you walk by. Cut the branch to the ground. Don’t be shy about cutting.
Then cut out any branches that broke during the spring’s wind or are crossing and rubbing. (This almost always requires a handsaw). Cut those branches to the ground. New shoots, suckers, will replace them to create shorter branches that will be covered with flowers within the next two years.
Cut out the dead wood, and you will be amazed at how much better the entire plant looks!
To slightly lower the height of the shrub, cut the tallest branches back to the first side shoots, which will produce blooms next year. Cutting a few of the canes, the branches, clear to the ground will promote the growth of new branches that will bloom at a shorter height.
Some special considerations:
Rhodies do not really thrive on this side of the mountains, so people are reluctant to cut them until they have grown up over the windows. You can prune Rhodies back much further than you think if you do it at the right time. The right time is within about 10 days of the blooms falling off. When you cut the tops of the branches, the heavy stems will produce new side branches at the height you hoped for — and the plant will bloom next year. If you have missed this pruning time, you will reduce the number of blooms for next year, but you will have restored your view.
When the Wisteria is the size you want it to be, maintain it by taking off all the summer runners. This shrubby vine is the greatest problem to prune because generally, pruning requires a ladder.
A great source for pruning information is Cass Turnbull’s “Guide to Pruning.” The author is witty and provides easy instructions for growing and pruning flowering shrubs as well as other plants.
A WSU Master Gardeners of Chelan County column appears weekly in the At Home section. Bonnie Orr is one of three columnists featured.