Deadheading, Disbudding and Plant Care
Dead flower heads should be removed from plants to prevent them from setting seeds, which diverts their energy from producing further . Deadheading also gives a tidier look to the garden and prevents the build-up of fungal in rotting material. Seed heads which are allowed to ripen also attract seed-eating birds which can cause physical damage to other parts of the plant — African and French marigolds are often destroyed in this way.
Deadheading of early flowering perennials, such as delphiniums, lupins and violas, will often encourage a second show of flowers later in the season.
Do not deadhead plants which are grown for decorative fruits or seed heads. Also, if you want to save some seeds for the next season, allow one or two blooms to wither on each plant. Harvest the seeds only when the pods are dry and ripe.
You can deadhead soft-stemmed annuals and perennials by hand. With finger and thumb, snap off flowers with a twisting motion as soon as they fade. You will need scissors or secateurs to deadhead those with tougher or wiry stems — do not tear the stem or loosen the roots by attempting to break stubborn stems by hand. Badly bruised or torn stems will die back and look unsightly or kill the whole plant. Make all cuts diagonally, sloping away from a growth bud, so that water runs off.
Dead flower heads should not be put on the compost heap — any seeds which have ripened may remain dormant for up to several years and germinate in unwanted places when the compost is distributed around the garden. Preferably burn this material instead.
The dead flower heads of certain plants can look attractive in autumn or winter and these can be left intact. The heads of many hydrangeas, for example, take on bronze and purple hues as the petals dry out. In addition, they afford some protection from winter frosts for sensitive dormant growth buds — leave them on the plant until the following spring. The dead flower heads of summer heathers are also attractive.
Disbudding involves removing unwanted buds so as to direct the whole of a plant’s energies into a few buds. It is done to produce extra large sized blooms — particularly of carnations,, dahlias and grown for exhibition. All buds but one on each stem are removed as soon as they can be handled — generally about the size of a pea — by rubbing them out between thumb and forefinger, or by cutting them off with a sharp knife
When growing blooms for a specific date — an exhibition or a birthday, for instance — disbudding can be timed accordingly. To delay flowering of the main crown bud, allow side buds to grow on side-shoots up to 5cm (2in) long before removing them. The time from securing the bud until the bloom is ready varies according to the species and variety. With chrysanthemums, for example, this period is six to nine weeks, depending on the feeding programme Plants which naturally produce sprays of flowers can be disbudded to ensure more uniform heads. With, for example, remove the larger centre buds and the smallest buds from each cluster.
When growing the highest quality flowers for exhibition or cutting, it may be necessary to protect them from heavy rain, hail and high winds. Staking early and correctly will help to reduce wind damage, as will a site sheltered from the prevailing wind.
To reduce wind damage further, plant or build windbreaks around the growing area —plants, timber or plastic. Rigid plastic screens with a perforated or slatted construction give the best results, allowing air to pass through, but at a significantly reduced speed. Solid structures such as fences and walls can create damaging turbulence around plants downwind of them.
For very valuable blooms, construct an open-sided timber framework with a sloping roof around and over the plants. Cover the top with tough, clear polythene or PVC sheeting once the flower buds begin to show colour —no earlier or plants may develop weak, straggly stems due to the slightly reduced light.
Flowers rich in nectar can be mutilated by birds — especially spring-flowering crocuses. A chemical spray-on deterrent is available which can remain effective for up to eight weeks, but results may be rather variable. Alternatively, construct a framework of dark-coloured, unobtrusive sticks or canes around the plants and stretch black cotton back and forth between them in a lattice-work. Few birds risk getting trapped under the cotton.
Rich, fertile soils generally produce the largest, lushest plants, but in some cases they encourage luxuriant foliage at the expense of flowers. Many annuals, including nasturtiums (Tropaeolum majus), can be disappointing on well-prepared soils. A sunny, quite dry spot with relatively poor can give much showier displays of flowers. Succulent plants, such as stonecrops (Sedum) and mesembryanthemums, are also reluctant to flower well when the soil is too moist — in nature they may only flower and subsequently set seeds when the life of the plant is threatened by drought or intense heat. For the same reason do not use fertilizers high in nitrogen on shy-flowering plants.
In recent years, Fl hybrids — especially of annuals — have become popular Many of these produce larger, showier flowers which may also be more resistant to rain, wind and disease. Where any of these problems have occurred in previous years, switch to an Fl hybrid selection. It is pointless to save seed from such annuals; they do not breed true.
Aspect is often very important in determining the display of flowers. A sun-loving plant grown in shade may produce a reasonable amount of healthy foliage, but few or no flowers.
F2 hybrids — second generation hybrids — also have improved flowering qualities over the open-pollinated varieties. They are not quite as spectacular as Fl hybrids, but the seeds are somewhat cheaper to buy.