Techniques to encourage repeat flowering
• Chelsea Chop This produces a succession of flowers, makes growth compact and bushy, and reduces the need for staking. As its name suggests, it’s something you should do around the time of the Chelsea Flower Show, from late
May to early June. Cut back the stems of herbaceous perennials by a third to a half using shears or secateurs (secateurs are more precise). Flowers are smaller but greater in number and it extends the flowering season. Pruning closer to flowering time increases the delay in flowering, as regrowth takes longer. If you have several clumps of one cultivar, cut each group back to varying degrees. If you only have a single drift then cut those at the front back harder than those at the back. Deadhead to produce more flowers.
• Hampton Hack Another technique that takes its name from a flower show. Particularly useful for herbaceous geraniums, such as G. sylvaticum, G. endressii and G. phaeum, it involves shearing back herbaceous plants to just above ground level, just after flowering. This encourages a flush of new foliage, further flowers and stops self-seeding.
It is a useful way to manage Alchemilla mollis after flowering and prevent it from becoming a weed. An alternative approach to controlling lady’s mantle is to pull off the flowered stems at the base immediately after flowering. Water, if needed after cutting back, and apply a general fertiliser help to promote regrowth.
• Deadheading Deadhead roses by cupping your hand around the whole bloom as the flowers fade, to prevent the petals from scattering on the ground. This technique also applies to camellias and peonies. Cut off the individual flowers of cluster-flowered roses as they fade, then prune back the stem by around 15cm to a strong, healthy leaf once the cluster has finished flowering. Hybrid tea roses should also be removed to a strong outward facing bud. Deadhead rhododendrons with your finger and thumb, carefully snapping off spent flower clusters at the base and taking great care not to damage or break off the soft, new spring growth. Deadhead buddlejas and lilacs by cutting off spent flowerheads with secateurs to a pair of leaves behind the flower to encourage further blooms. Don’t remove the spent flowers of plants that produce ornamental fruit, if you want to save seed or if the seeds or fruit are of benefit to wildlife.
• Further reading The Well-Tended Perennial Garden: the Essential Guide to Planting and Pruning Techniques by Tracy DiSabato-Aust (Timber Press, 2017). A completely revised and expanded version of the definitive work on this subject.