The single most common pruning mistake is timing, not technique - cutting a spring-blooming shrub in fall removes the buds it already set for next year’s flowers. The right time depends on when a plant blooms and whether it flowers on old or new wood, not the calendar month alone.
Lilac, forsythia, and azalea bloom on “old wood” - branches that grew the previous year. They set next year’s flower buds shortly after this year’s bloom finishes, so pruning immediately after flowering (not in fall or late winter) is the only window that doesn’t sacrifice next season’s flowers.
Butterfly bush, panicle hydrangea, and rose of Sharon bloom on “new wood” grown the same season, so cutting them back hard in late winter before growth starts doesn’t remove any flower buds - it actually encourages the vigorous new growth that produces the summer bloom.
Apple, pear, and stone fruit trees are pruned in late winter while fully dormant and leafless, which makes the branch structure easy to see and reduces disease transmission risk compared to pruning during active growth.
Ornamental grasses and seed-head perennials (coneflower, black-eyed Susan) can be left standing through winter for both visual interest and bird food, then cut back to a few inches in very early spring before new growth emerges - rather than the traditional fall cleanup, which removes habitat for no real horticultural benefit.
Simon runs a small perennial nursery on weekends and writes our native-plant and soil-health coverage. He is happiest arguing about compost …
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