Cutting back flowers is a horticultural practice that encompasses two main activities: deadheading and pruning. Deadheading involves the selective removal of spent or faded blooms, while pruning is the more substantial reduction of plant material to control size and shape. Both techniques are performed to maintain the health of the plant and to actively encourage a more vigorous and extended display of flowers. Mastering the proper timing and technique for these cuts ensures that the plant directs its energy into producing new growth rather than completing its natural reproductive cycle.
Understanding Why Flowers Need Cutting
A plant’s primary biological function is to reproduce by creating seeds inside the flower heads. Once a flower fades, the plant diverts significant energy reserves to developing those seeds. This process signals that its reproductive purpose for the season has been fulfilled, often halting the production of new flower buds.
Removing spent blossoms, or deadheading, tricks the plant into believing it has not yet completed its mission. By interrupting the seed-setting process, the plant redirects stored energy back toward vegetative growth and the formation of new blooms. This mechanism extends the flowering period, especially for annuals and repeat-blooming perennials.
Pruning is also performed to remove dead, diseased, or damaged stems, which can harbor pests or fungal spores, thus improving overall plant hygiene. Thinning out dense growth increases air circulation through the plant canopy, reducing the risk of common foliar diseases.
Necessary Tools and Making the Proper Cut
The quality of the cut directly impacts the plant’s ability to heal and the risk of disease entry, making sharp, clean tools essential. For herbaceous stems and branches up to about a half-inch thick, bypass hand pruners are the preferred tool because they make a clean, scissor-like cut. Bypass pruners create minimal tissue damage compared to anvil pruners, which crush the stem against a flat surface. For thicker, woody material, long-handled loppers or a pruning saw may be necessary.
The proper technique involves locating a leaf node, which is a slightly swollen point on the stem where a leaf or bud is attached. Cuts should be made approximately one-quarter inch above an outward-facing bud or a set of healthy leaves. This positioning encourages new growth to sprout away from the center of the plant, improving light penetration and overall shape. Making the cut at a 45-degree angle allows water to run off the wound quickly, reducing the opportunity for fungal pathogens to enter the plant tissue.
When to Cut Back Specific Types of Plants
The optimal timing for cutting back depends on the plant’s life cycle and whether it blooms on old or new wood. For annuals, the goal is continuous bloom, meaning deadheading should be performed regularly as soon as flowers begin to fade. If the plant becomes leggy or sparsely flowered, a more aggressive cut, called a “shear,” can remove the top few inches of growth to stimulate a fresh flush of foliage and blooms.
Many perennials benefit from the “Chelsea Chop,” which involves cutting back the stems by a third to a half in late spring. This process delays flowering but produces a more compact, sturdier plant and often results in a second flush of blooms later in the summer. Fall cutbacks should wait until after the foliage has turned brown and the plant has entered dormancy, though leaving stalks standing provides winter interest and shelter for beneficial insects.
Flowering shrubs require precise timing based on when they set their flower buds. Spring-blooming shrubs, such as lilacs, set their buds the previous summer, so they must be pruned immediately after flowering to avoid removing the next season’s buds. Conversely, shrubs that flower in summer on new growth, like many hydrangeas, are best pruned during their dormant season in late winter or early spring. For roses, a hard cut in early spring removes older canes and encourages robust new growth from the base.
Care Immediately Following Pruning
After making the necessary cuts, attention to the area around the plant ensures a swift recovery. All pruned plant material, especially anything diseased or damaged, should be promptly removed from the garden area. Leaving this debris on the ground can create a breeding site for pests and fungal issues and prevent the spread of pathogens.
Proper watering is required after a significant pruning session, as the plant may experience shock. Provide a deep watering to the root zone to compensate for the sudden loss of foliage and water through transpiration. Avoid overwatering, which can lead to root rot.
Resist the impulse to apply heavy fertilizer immediately after cutting back, as this can burn the newly exposed tissue. Instead, wait for two to three weeks until you observe signs of active new growth. At that point, a light application of a balanced, slow-release fertilizer will support the energy demands of the new foliage and blooms.