Fading flowers make beds, borders and pots unattractive, and removing these by deadheading is part of the summer garden cycle to get the best from your flowers.
Single flowers usually produce seeds, which soaks up the plant’s energy. Lilies are a typical example, where seedpods are best removed so that the plant focuses on a bigger bulb for next year.
Plants to be deadheaded include bedding plants and other tender perennials including canna and dahlias, which will reward you with flowers until the autumn frosts.
Simply pluck, break or snip off the spent flowers and add to the compost heap. Remove the stalk, too, as stalk remnants are also unsightly. Deadhead to a pair of healthy leaves.
Use finger and thumb, scissors, snips, knife or secateurs, depending on the strength and thickness of stems. Using the easiest, quickest method aids timeliness – leaving spent flowers for two weeks before removing them is much less effective than being rid as soon as they are over.
Red poppies in the wildflower meadow at Gordon Castle Walled Garden, Moray, Scotland (Photo: Julia Stanley/RHS)
Free-flowering bedding plants including cosmos, dahlias and pelargoniums can need almost daily deadheading for best results in the heat of summer. They will go on flowering if neglected, but they won’t flower as well and will look ragged.
It is not worth deadheading annual plants, as flowering signals the end for them. Unless self-seeding is intended, they are best swept away and something else sown or planted.
Poppies and nigella flowers are often retained for their very ornamental seed pods. Self-seeding is often hoped for, particularly for cornfield annuals and other wildflowers and for the many “floral meadows” of annual plants, and here deadheading is omitted so the plants can scatter seeds for next year.
Certain prolific plants – Alchemilla mollis, for example – can appear over wide areas and become a nuisance unless their seedheads are controlled.
Some plants shed flowers of their own accord and need little or no deadheading, including angelonia, begonias, nicotiana and some calibrachoa and petunias. Those that flower in spikes – such as antirrhinums – are easy to deadhead: simply snip out the finished flower spike.
The best time to deadhead is when the flower has wilted (Photo: Helen Yates/RHS)
Many herbaceous plants won’t reflower if deadheaded, but cutting back keeps them neat. Plants that are reluctant to produce flowers following deadheading include hardy geraniums. Shearing these probably won’t lead to more flowers, but new bright foliage will form. Lupins and delphiniums, cut back as soon as flowering is over, produce fresh new foliage and a smaller but valuable late summer or early autumn crop of flowers.
Repeat-flowering roses are often the most important subjects of deadheading, where the faded blooms are removed with secateurs in gloved hands. Cutting out spent flower shoots with secateurs to a healthy leaf is all that is needed. Cutting lower down delays flowering. Snapping of individual flowers of hybrid tea roses leads to faster reflowering.
Feeding after deadheading probably does some good if the soil is not fertile, but ideally mulch and feed in spring to carry the plants through to autumn. Liquid-feeding pots is important, however.
Other flowers that are up and coming, with flowering expected later in summer and into autumn, can be pinched if desired. Pinching is literally removing the bud at the tip of the plant. That top bud inhibits buds lower down the plant and once it is removed, two or more new shoots arise. The result is bushier growth, shorter sturdier plants and more, if slightly later, flowers. Flowers sown in May such as cosmos, sunflowers and zinnia are likely to benefit.
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