Belgian gardeners advised against pruning hydrangea and lavender in August

In Belgium, gardeners are warned that pruning hydrangea (hortensia) in August can remove the flower buds formed for the next season, resulting in few blooms the following year. Species such as the common bigleaf hydrangea (Hydrangea macrophylla) and oakleaf hydrangea set buds from late July through August, so cutting them at this time eliminates the next year's flowers. While some hydrangeas that flower on old wood are best pruned only in late winter or early spring, others that bloom on new wood benefit from early‑season pruning, not from August cuts.

Similarly, lavender should be trimmed after flowering, ideally in late July or early August, but only the spent flower stems should be removed. Cutting back to old, woody growth harms the plant by creating bare spots and can lead to death. Gardeners are advised to cut just above the green foliage, remove dead or damaged stems, keep the plant well‑watered during dry spells, and apply mulch to protect roots as the season progresses.