If these are kinds that bloom in summer, on new wood you may see some.
The reason pivots on the fact that pruning now will remove the tight/compact summer growth that is desirable, and leave you with a winter's worth of leggy growth/long internodes that's quite undesirable. OTOH, if you wait until spring to prune, you'll be removing the winters undesirable growth and replacing it with tight summer growth.
Mar 02, Give it a good trim after it flowers in the spring by cutting back the tips of the stems to the top leaf bud.
This removes the dead blossoms and also may trigger a second blooming and new leaf growth. You can also shape the shrub at this time. More drastically cutting back spirea should occur in the fall or in late winter to early spring. Oct 25, Spirea pruning not only rejuvenates the plant and encourages blooming, but it also helps to restrain the size of the shrub. Also, trimming spirea back, in many cases, will induce a second bloom.
Other varieties of spirea, such as Japanese spirea, respond better to pruning in the late winter months. Mar 30, Prune away old, mature canes to make way for new growth. Old canes may still produce foliage, but they prevent growth and block the sun from reaching the lower branches.
Cut them off at the base of the plant. In the fall or late-winter, prune the spirea again. This trim is Estimated Reading Time: 5 mins. Spirea White – Pruning, Winter Care and Fertilizing Spirea White, includes Bridal Wreath, Snow White, Snowmound, Fairy Queen and Thor Birchleaf.
Not Japanese White, see pink spirea. Prune these spring flowering shrubs soon after they have bloomed. Top prune the plant to improve the shape and reduce its size but, be careful not to remove more than 30% of the top growth. These shrubs need little winter care but, should be occasionally checked for rabbit or other damage. If rabbit damage is found you can protect the plant with a fence formed with hardware cloth (looks like chicken wire but, with small square holes).
Heavy pruning in late winter or early spring will reduce or eliminate the flower display for 2 or 3 years. However, rejuvenation pruning will restore the health of the shrubs. The best time to prune healthy, well-maintained spring-flowering shrubs is immediately after flowering. Dec 10, Pruning Bridal Wreath Spirea in Winter During bridal wreath spirea bloom time in spring, buds will grow from its greenwood branches, so heavy pruning is not advised, as it.