Removing spent flowers will ensure your hydrangeas produce healthier, more bountiful blooms later on.
In addition to encouraging hydrangeas to produce more flowers, pruning these shrubs each year helps keep them healthy if they get damaged by weather and allows you to shape them however you like.
Deadhead After Flowers Die
If you do this early enough, you may encourage the plant to set a second flush of blooms. "The hydrangeas that flower on the new wood will sometimes flower again, if you remove the old flowers early enough to promote new growth to produce new flowers," says Becker.
If it blooms on old wood (stems from the summer before the current one), its buds are being formed, and if you wait too late you may cut them off, meaning no flowers next spring. So these shrubs should be pruned immediately after their flowers fade.
Without going through the deadheading process, hydrangeas will not produce as many flowers and the few produced may not grow as big to their full potential.
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
To rejuvenate the hydrangea, remove up to 1/3 of the older living stems down to the ground each summer. This will revitalize the plant. If necessary to control the size of the plant, cut back before late July to allow for buds to develop. Usually the plant will return immediately to its former size.
Coffee grounds add extra acidity to the soil around hydrangeas. On a chemical level, this increased acidity makes it easier for the plant to absorb naturally occurring aluminum in the dirt. The effect is pretty blue clusters of flowers.
Hydrangea Care Tips
Water at a rate of 1 inch per week throughout the growing season. Deeply water 3 times a week to encourage root growth. Bigleaf and smooth hydrangeas require more water, but all varieties benefit from consistent moisture.
Sometimes bigleaf hydrangeas become overgrown and need to be trimmed. However, too much pruning will greatly reduce or eliminate flowering. In late summer, after the bloom period, dried flowers can be removed.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
Deadheading your hydrangeas isn't a care step you want to skip. "Deadheading allows the energy produced by the plant to go into the leaves, stems, and roots (rather than forming seeds) for future growth," says Melinda Myers, a professional gardener.
Unlike other flowers, deadheading hydrangeas will not make them bloom again. Regular hydrangeas bloom once per season, while reblooming varieties produce a second set of flowers later in the season on new stems.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon. The reblooming Endless Summer® Hydrangea series prefers part shade. These include BloomStruck®, Endless Summer®, Blushing Bride®, and Twist-n-Shout®.
Miracle-Gro Performance Organics Blooms Nutrition
This is an all-purpose blossom booster that's suitable for use on a wide variety of perennial and annual blooming plants, including hydrangeas. It provides various minerals, including copper, calcium, and iron, to supplement common nutrient deficiencies.
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum. In addition, fruit peels, lawn clippings, peat moss and pine needles, are thought to have a similar effect.