When should you prune spring-flowering shrubs versus summer-flowering shrubs, and why?

When should you prune spring-flowering shrubs versus summer-flowering shrubs, and why?

• A. Spring-flowering after bloom; summer-flowering in late winter or early spring before bud break; to avoid removing next year's flowers on wood
• B. Spring-flowering in late winter; summer-flowering after bloom; to encourage more flowers
• C. Both types should be pruned in mid-summer; to maintain shape
• D. Spring-flowering shrubs should be pruned right after flowering; summer-flowering shrubs should be pruned in late winter; this preserves next year's bloom

Answer: (D)

The key idea is whether a shrub forms its flower buds on last year's wood or on the current season’s growth. Spring-flowering shrubs set their buds on wood from the previous year, so pruning after they finish blooming protects those next-year buds. If you cut them earlier, you risk removing flowers that would appear next spring. Summer-flowering shrubs form their flower buds on new growth produced this season, so pruning in late winter while the plant is dormant promotes fresh growth that will carry the next round of blooms. Pruning them at that time helps ensure robust flowering later in the year. This timing matches the need to preserve or encourage future blooms, which is why it’s the best approach. For context, lilac and forsythia are spring-blooming; butterfly bush and many crape myrtles are summer-blooming, illustrating the old-wood versus new-growth rule.