There are over 100 species of deciduous shrubs that fit into the Spiraea genus, many from Asia, but a few from North America. Locally, we can find birch-leaved spirea (Spiraea betulifolia) in the forest. For home gardens, most of the plantings are woody shrubs that lose their leaves in winter, but maintain their upright shape. They are valued for their clusters of small white flowers in the spring.
They can grow a foot in a single year and gardeners will need to prune to keep the mounding shape. Many shrubs flower on last year’s wood so thoughtful pruning will yield a better supply.
Some species bloom on the current year’s wood, like the Japanese spirea. They tend to be shorter and maintain a compact shape, but they can be quite invasive. The remedy is to remove all seed heads after flowering, but this increases the maintenance level.
We have a number of spirea shrubs in the yard, but we have also removed dozens of self-seeded plant this year. In general, the best choice is spring-blooming spirea. Japanese spirea can be planted in space where we can prune regularly, but over time we are removing these low-growing shrubs.
