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Spirea, sometimes called Bridal Wreath, are stunning deciduous shrubs, full of blooms that grace the overhanging branches in small clusters of white flowers that smother the branches. The mounded growth can get quite tall, upwards of 1-2 metres with blue-green leaves that remain visually appealing throughout the summer, long after the late spring flowers are gone.
The issue that such plants, while stunning, can at times stop producing flowers. In fact, otherwise healthy plants that previously produced flowers can stop seemingly out of nowhere. So what causes spirea to stop flowering?
There are a few reasons:
If you have had particularly harsh winters, the flower buds that formed in previous seasons could be damaged and therefore, not flower. Harsh winter weather without a lot of snow cover can cause more injuries to your spirea than snow heavy winters, because the snow at least gives them insulation.
Sunlight is also a factor. If you don’t give your plants enough sun, they won’t grow. So sometimes you might need to move the spirea to a new location where it gets full sun. Like many flowering plants, it can still survive in less than adequate sun conditions, but the lack of sunlight will hinder the floral development and stunt growth.
Pruning at the wrong time of year
Pruning can also cause problems with flowering. If you prune your shrub at the wrong time of the year, the flower buds can accidentally get removed. If you wait until it is too late in the summer or Autumn, for example, the pruning might cut back the buds that would otherwise grow the following spring.
These plants need pruning regularly to keep them from becoming too leggy, remove full lengths of spent flowers every year which can mean pruning out around 2ft of established plants. You can if you want prune very hard to almost ground level so that the entire plant is rejuvenated every 3 years to encourage more flowering shoots low down. But make sure it is at the right time of the year to prevent cutting off the flowering shoots that have formed the previous season. Ideally, most varieties which include Spiraea ‘Arguta’, Spiraea Snowmound, Spirea Little Princes, Spiraea japonica Shirobana need to be pruned straight away after flowering which is usually June.
So, make sure you give it the right sunlight, protect it during winter, and prune at the right time of the year.