Last updated on April 22nd, 2022
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Spiraea, 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 have finished.
The issue with such plants, while stunning, is that they can (at times) stop producing flowers. In fact, otherwise healthy plants that have previously produced flowers can stop seemingly out of nowhere. So what causes a Spiraea to stop flowering?
There are a couple of reasons, and these will talk about in more detail below.
If you have experienced a particularly harsh winter, the flower buds that formed during the previous season could have been damaged and therefore, will not flower. Harsh winter weather without a lot of snow cover can cause more injuries to your Spiraea than heavy winters with snow because the snow will, at least, give them some insulation.
Sunlight is also a factor. If you don’t provide your plants with enough sun, they won’t grow. Therefore, in some circumstances, you might need to move your Spiraea 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 be removed. If you wait until it is too late, in the summer or autumn, for example, any pruning might actually 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 away around 2ft from your established plants. You can (if you want) prune them very hard, almost to ground level, once every 3 years so that the entire plant is rejuvenated. This will encourage more flowering shoots low down. Again, make sure this is done at the right time of year to prevent cutting off the flowering shoots that have formed the previous season.
Ideally, most varieties, which include Spiraea ‘Arguta’, Spiraea ‘Snowmound’, Spiraea ‘Little Princess’, and Spiraea japonica ‘Shirobana’ need to be pruned straight away after flowering which is usually around June.
Overall, if you make sure you are providing your Spiraea with the right amount of sunlight, protecting them during the winter, and pruning them at the right time of the year, your Spiraea should reward you with a fantastic display of flowers.