The ‘Incrediball’ hydrangea is a celebrated cultivar of the smooth hydrangea species, Hydrangea arborescens. This North American native shrub is highly valued for its massive, snow-white flower heads and its robust, improved stem strength compared to older varieties. Pruning is necessary maintenance, ensuring the shrub directs energy toward producing strong, new growth and the largest possible blooms each season. Understanding the proper timing and technique for cutting back the plant is simple.
Optimal Timing for Pruning
The correct timing for pruning the ‘Incrediball’ is determined by its specific flowering habit: it blooms exclusively on “new wood,” which is the growth produced during the current growing season. This characteristic simplifies the pruning schedule considerably, as there is no risk of removing flower buds that formed on old, overwintered stems. The primary, structural cutback should occur when the shrub is dormant, specifically in late winter or very early spring, just before new green growth begins to emerge.
Pruning during this dormant window allows the plant to use its stored energy to push vigorous, strong shoots immediately as the weather warms. A secondary, minor pruning can involve deadheading the spent flowers in the summer or fall. Deadheading improves the plant’s appearance and can prevent the heavy, dried flower heads from flopping over. If you enjoy the visual interest of the dried blooms in a winter landscape, you can safely leave them on the shrub until the main spring prune.
Step-by-Step Pruning Methods
Before beginning the annual cutback, gather clean, sharp bypass pruners to make precise cuts that heal quickly. The first step involves sanitation cuts: identify and remove any wood that is dead, diseased, or damaged, taking these stems right down to the ground. Removing this material improves air circulation within the shrub’s center, which helps prevent disease.
Next, focus on removing any branches that are crossing or rubbing against each other, as this friction can create wounds that invite pests or pathogens. Once the plant is cleaned up, proceed to the annual structural reduction, which involves cutting back the remaining healthy canes. For a dense, compact shrub, reduce the entire plant’s height by approximately one-third, often cutting back to a height between 12 and 24 inches from the ground.
The precise cut should be made just above a pair of strong, visible leaf buds or a growth node. By making the cut slightly angled, you encourage water to run off the wound, promoting quick healing. Maintaining a permanent framework of established, woody branches provides necessary support for the massive flowers, which is important for this cultivar.
Understanding New Wood Bloom and Rejuvenation
The ‘Incrediball’ hydrangea’s ability to bloom on new wood gives gardeners great flexibility in their pruning approach. This sets it apart from hydrangeas that flower on old wood. Even if the plant is severely damaged by a harsh winter or cut back drastically, a full display of blooms is guaranteed in the summer. This resilience allows for a more aggressive technique known as rejuvenation pruning.
Rejuvenation is an optional, heavy cutback used to reset an overgrown, woody, or poorly shaped shrub, or to encourage the strongest possible new growth. This technique involves cutting the entire shrub down dramatically, often to a height of just 4 to 6 inches from the ground. The benefit of this ‘hard chop’ is that the resulting new stems are often thicker and more vigorous, which better supports the weight of the large blossoms.
A consequence of this severe pruning is that the shrub may initiate flowering slightly later in the season compared to a lightly cut back shrub. If the ‘Incrediball’ is cut back too low every year, the resulting stems may be vigorous but potentially weaker at the base, risking flopping under the weight of the blooms after heavy rain. Therefore, a one-third annual reduction is recommended to build a supportive, permanent structure, reserving the full rejuvenation cut for every few years as needed.