It won’t be long before the romantic, old-fashioned shrubs begin to bloom. Though everything here in Northeastern PA is dreary and some snow still lingers along with temps below freezing, it’s actually great thinning weather for the bridal wreath spirea (Spirea vanhouttei) and other flowering shrubs. In May, the arching flower laden branches of the “Bridal Wreath” will put on a gorgeous display of white cluster-shaped blossoms to the delight of garden visitors (both human and the pollinating kind).
The best time to thin these quick growers is in late winter or early spring while they are dormant. It’s easy because there isn’t any foliage and the structure is easily seen. I can’t get enthusiastic about climbing around in snow and ice to do this so as soon as the snow melts and I can get to the base of the shrubs I begin the task. Today is March 20, 2014 and it’s the first day of spring. It’s a brisk sunny day, so I’m on it.
Since I prefer the loose naturally flowing shapes of shrubs as opposed to the neatly manicured “balled” look, I cut out one-third of the oldest branches to the ground every other year. Rarely do I ever cut back the tips, unless they are planted near a walkway and need a gentle trim. There’s nothing wrong with a little shaggy shrubbery! It adds a bit of romance to the garden. (Everything doesn’t have to be trimmed into topiary.)
Begin by counting the number of branches coming out from the base of the shrub. Let’s say there are 22. Divide that number by 3 to arrive at 7.33 (round down to 7). You will remove 7 branches from the shrub as close to ground level as you can get with your loppers. I suggest using safety glasses while doing the thinning. I’ve had previous experience with some wild branches!
I marked the branches for removal with tape for this photo. It is best to remove no more than one-third of the total number of branches in order to keep the shrub in good health. Now look for the oldest (usually thickest) branches and remove them first. They will be more gray than the newer growth which is a warm brown. If there are any dead branches clip them out as well. They don’t count, they are already dead.
Thinning out the older branches will open up the base and center of the shrub allowing light in. In a few weeks, new shoots will form and the following spring they will bloom. If you are crafty, the thin soft tips of the cut branches can be trimmed into smaller sections about 18 inches long and formed into wreaths or swags.
I have rejuvenated many old, tired-out shrubs that lacked blooms with this method and the results are amazing. In a few years they regain their vitality and blooms increase. This works wonders on older mock orange (Philadelphus) and lilac (Syringa) too. When working with very mature shrubs, plan to thin over three years in order not to place too much stress on the shrub.
Bridal wreath spireas are a low-maintenance way to bring structure and seasonal interest to your space. They are very forgiving and will still continue to bloom even if they are neglected. If you are considering a garden wedding in the backyard in May, then give this shrub a chance to attend the ceremony.