Native Plants

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Thursday - April 23, 2015

From: Reading, PA
Region: Mid-Atlantic
Topic: Non-Natives, Pruning
Title: Non-Blooming Bridal Wreath Spirea in PA
Answered by: Anne Van Nest

QUESTION:

We have 12 - 15 Bridal Wreath Spirea across our backyard. We have lived here for about 10 years (the plants longer). They have always bloomed except last year (2014) several didn't bloom and this year (2015) only about one to one and a half have bloomed (and not very much). Are they dead or should we cut them back almost to the ground in hopes of saving them? We have had two really bad winters in the last two years. Could this have affected them?

ANSWER:

Even though Bridal Wreath Spirea (Spiraea vanhouttei or S. prunifolia) are not native, Mr. Smarty Plants does have some suggestions about why the plants are not blooming.

It could be the two previous bad winters. The flower buds on bridal wreath spirea are formed during the previous year and could have been damaged by an unusually harsh winter. This spirea is hardy to USDA zone 5 (and Reading is in zone 6b) so low temperatures shouldn't normally be an issue. But a harsher winter with less insulating snowcover could injure the plants.

Also if the shrub is pruned at the wrong time (too late in the summer or in the fall) then the flower buds will be removed and the shrub will not bloom the next year.

Bridal Wreath Spirea does regularly need rejuvenation pruning to stop it from getting too leggy so they can be pruned back hard (or pruned back strategically 1/3 each year over three years) to bring it back to a better health and shape - this is particularly important if they are quite old.

Lastly, they will bloom and grow fuller if they are in full sun. Are yours still getting full sun?

The Missouri Botanical Garden has information on the plant that may help. As well as Clemson University Extension.

By the way, there are several native Spiraea that grow in PA. Click on the images below to take a look.