Deadheading, the practice of removing spent or faded flowers, helps redirect a plant’s energy away from seed production and toward stronger growth and foliage. However, whether you should cut off a dead hydrangea bloom, and the specific technique for doing so, depends entirely on the variety you are growing. Misidentifying your shrub’s type or using the wrong timing can inadvertently remove the buds for next year’s flowers, resulting in a lack of blooms.
The Critical Difference: Identifying Your Hydrangea Type
Not all hydrangeas are created equal when it comes to pruning; the most significant distinction lies in whether they bloom on “old wood” or “new wood.” Old wood refers to the stems that grew the previous season, and the flower buds for next year are formed on these stems during the late summer or early fall. The Hydrangea macrophylla (Bigleaf) and Hydrangea quercifolia (Oakleaf) are common examples. If you cut back an old wood bloomer too aggressively or too late, you are removing the buds that would produce the next season’s flowers.
Conversely, new wood bloomers set their flower buds on the stems that grow in the current season. These include Hydrangea paniculata (Panicle) and Hydrangea arborescens (Smooth). These varieties are much more forgiving of pruning and can be cut back harder without sacrificing the floral display, as they produce new flowering stems every spring.
Practical Instructions for Removing Spent Flowers
The technique for removing spent blooms must be tailored to the specific growth habit of your shrub to avoid damaging the plant or removing future buds. For old wood bloomers (H. macrophylla and H. quercifolia), timing is important and should occur immediately after the bloom fades in early to mid-summer. The cut should be made precisely above the first set of large, healthy leaves located directly below the faded flower head.
It is important to stop all deadheading and pruning on old wood varieties by mid-August, as this is when the plant begins to set the flower buds for the following year. Use clean, sharp bypass pruners to make a clean cut just above a pair of leaves or a visible bud. This ensures the plant can quickly seal the wound and put energy into the neighboring growth point.
For new wood bloomers (H. paniculata and H. arborescens), the timing for removing spent flowers is much more flexible. You can deadhead them in the late summer for tidiness, or wait until late winter or early spring before new growth appears. Because the buds form on the new growth, a cut can be made further down the stem to shape the shrub, which is often done in the spring to control the plant’s overall size. Removing the faded flowers on these types is mainly for aesthetic purposes or to prevent the weight of snow from breaking the stems.
Reasons to Leave Blooms on Through Winter
While deadheading during the growing season can encourage reblooming in some varieties, leaving the faded flowers on the shrub through the fall and winter is a common and beneficial practice. The dried, brown flower heads often provide significant visual interest in a winter landscape, particularly the cone-shaped blooms of Hydrangea paniculata, which can take on beautiful antique colors as they dry.
Beyond aesthetics, the spent blooms offer a minor degree of insulation and protection for the delicate dormant buds below, especially for sensitive old wood varieties like H. macrophylla. The faded flower acts like a small protective cap against harsh winter conditions. For most hydrangeas, the final cleanup cut is best delayed until early spring, usually in March or April, just before the new growth begins to emerge, ensuring maximum protection during the coldest months.