Planning an early-autumn outdoor wedding? Prolong or delay the flowering of hardy perennials by selective hard-pruning. When monkshood (Aconitum spp.) reaches one metre in late May or early June, carefully (and courageously) remove the top one-third, flowerbuds and all. Or prune part of a large drift. This method also works with valerian (Centranthus), coneflower (Echinacea), leggy Gaura, Phlox, Penstemon, Salvia nemorosa and other perennials, contributing to the plant's sturdiness and later, prolific flowering. Delphinium spp. may give a second show - deadhead after initial blooming, and cut back stems by two thirds. It's a good idea to provide an extra top-dressing of compost or manure as compensation for this overtime work!