Hydrangeas produce clusters of tiny flowers on medium-sized bushes and vines. There are five types of hydrangeas: snowball hydrangea, peegee hydrangea, hortensia hydrangea, oakleaf hydrangea and climbing hydrangea. Hortensia, or "mophead" hydrangeas are perhaps the most recognisable type; they are commonly sold by florists and come in a variety of spring pastel colours. All varieties of hydrangeas can and should be deadheaded to make room for new blossoms, although gardeners choose different times to deadhead.
Reason for Deadheading
Deadheading hydrangeas is important if you want the plant to continue producing healthy, brilliant blooms throughout the flowering season. Varieties like Endless Summer hydrangeas, as the name implies, can produce flowers into late summer and autumn if they are well cared for. Plants expend a lot of energy to make beautiful flowers and after a flower expires, energy is used to create seeds. By deadheading flowers, you cut off the energy needed to produce seeds and divert that energy toward undeveloped flowers and creating new buds. Energy expense aside, many people deadhead hydrangeas simply because the dead blossoms look undesirable amid healthy flowers and bright green leaves.
Deadheading may be done from spring through fall as needed. Blooms from plants grown in healthy environments can last as long as four weeks before they wither and die. You be the judge as to the extent of withering you wish to allow before deadheading. Some gardeners like to keep only the brightest blooms on their plants and will remove a flower at the first sign of decay. Other gardeners may wait until a flower is completely brown before deadheading it. You can deadhead hydrangea flowers one at a time as they fade or wait until there are several dead flowers. It's important to note that the method for deadheading in June or July is different than deadheading after in August and later.
A pair of gardening shears or household scissors is all you need to deadhead hydrangea plants. You simply cut through the flower stem to remove it from the plant. Some people like to prune more of the plant when deadheading and may cut long stems. Cutting stems back like this helps to shape overgrown plants and can make the plant healthier. Cutting long stems is OK if done in June or July before the buds have set for the next year. If you deadhead plants in August or later, you should cut short stems to protect the buds that have already formed for new growth in the following year. Make the cut above the first sets of large leaves on each stem to avoid cutting the buds. A few remontant or reblooming hydrangea varieties, such as the Endless Summer hydrangea, are capable of regenerating bloom buds even if they are cut off.
The Case Against Deadheading
Gardeners may avoid deadheading because they believe leaving the dead blooms on the plant helps provides winter protection for bloom buds along the stem. The flowers are not deadheaded until the following spring, after all danger of frost has passed. Dead blooms are often left on plants to add some interest to the plant through the bleak winter months. Although the flowers are dead, they hold their round or cone shapes well, helping to accentuate the plant when it is lacking in foliage.