Understanding Why Hydrangeas Fail to Bloom
The biggest reason hydrangeas fail to bloom often comes down to one simple mistake: pruning at the wrong time. However, the answer isn't always that straightforward. Different hydrangea species develop flower buds in different ways, and weather conditions can also play a major role. Understanding which type of hydrangea is growing in the landscape is the first step toward enjoying reliable blooms year after year.
Some hydrangeas bloom on new wood, meaning they produce flowers on the current season's growth. These include Hydrangea paniculata (panicle hydrangea) and Hydrangea arborescens (smooth hydrangea). Because these plants form flower buds on fresh growth each spring, they can be safely pruned during the dormant season without sacrificing blooms. As temperatures warm, vigorous new stems emerge from the base of the plant and produce flowers later that same season. Gardeners may choose to remove all the previous year's stems or leave some of the old wood in place to provide extra support for the new growth.
Other popular hydrangeas bloom on old wood, which means their flower buds develop on stems produced during the previous growing season. This group includes Hydrangea quercifolia (oakleaf hydrangea), Hydrangea macrophylla (mophead or bigleaf hydrangea), and Hydrangea serrata (mountain hydrangea). These shrubs require a different approach. Do not prune them during late winter or early spring as this removes the stems that already contain flower buds, often eliminating the year's blooms before they have a chance to open. Fortunately, old wood blooming hydrangeas do not require routine pruning to stay healthy. If a shrub fits comfortably within its planting space and has a pleasing shape, it can simply be left alone.
If pruning is necessary on old-wood hydrangeas, it should be done immediately after the plant finishes flowering. This timing allows the shrub to produce new stems throughout the remainder of the growing season. Those new stems will mature into the old wood that carries next year's flower buds. When making pruning cuts, remove branches at a natural branching point rather than leaving short stubs behind. Deep, selective cuts help maintain the plant's natural form while encouraging healthy new growth.
Many newer mophead hydrangea cultivars add another layer of complexity because they are reblooming or remontant. These plants can flower on both old and new wood. Their spectacular spring display still comes from flower buds formed on the previous year's stems, but they also have the ability to produce additional blooms on new growth later in the summer.
Even when pruning is done correctly, weather can still affect flowering. A late spring freeze may damage flower buds on old wood before they open. In those years, the shrub may lose most or all of its spring bloom display. Reblooming hydrangeas often recover by producing some flowers on new growth later in summer, although this second flush is usually less dramatic than the abundant spring show.
By identifying whether a hydrangea blooms on old or new wood, pruning only when necessary, and recognizing the effects of late spring freezes, gardeners can greatly improve their chances of enjoying beautiful hydrangea blooms season after season.
Related Videos:
Common Hydrangeas
How do I keep my Annabelle hydrangea from flopping on the ground?
Why is my hydrangea not blooming?
When should I prune my Hydrangea Paniculata?
Related Resources:
Hydrangea paniculata
Hydrangeas
Pruning hydrangeas for best bloom
Some hydrangeas bloom on new wood, meaning they produce flowers on the current season's growth. These include Hydrangea paniculata (panicle hydrangea) and Hydrangea arborescens (smooth hydrangea). Because these plants form flower buds on fresh growth each spring, they can be safely pruned during the dormant season without sacrificing blooms. As temperatures warm, vigorous new stems emerge from the base of the plant and produce flowers later that same season. Gardeners may choose to remove all the previous year's stems or leave some of the old wood in place to provide extra support for the new growth.
Other popular hydrangeas bloom on old wood, which means their flower buds develop on stems produced during the previous growing season. This group includes Hydrangea quercifolia (oakleaf hydrangea), Hydrangea macrophylla (mophead or bigleaf hydrangea), and Hydrangea serrata (mountain hydrangea). These shrubs require a different approach. Do not prune them during late winter or early spring as this removes the stems that already contain flower buds, often eliminating the year's blooms before they have a chance to open. Fortunately, old wood blooming hydrangeas do not require routine pruning to stay healthy. If a shrub fits comfortably within its planting space and has a pleasing shape, it can simply be left alone.
If pruning is necessary on old-wood hydrangeas, it should be done immediately after the plant finishes flowering. This timing allows the shrub to produce new stems throughout the remainder of the growing season. Those new stems will mature into the old wood that carries next year's flower buds. When making pruning cuts, remove branches at a natural branching point rather than leaving short stubs behind. Deep, selective cuts help maintain the plant's natural form while encouraging healthy new growth.
Many newer mophead hydrangea cultivars add another layer of complexity because they are reblooming or remontant. These plants can flower on both old and new wood. Their spectacular spring display still comes from flower buds formed on the previous year's stems, but they also have the ability to produce additional blooms on new growth later in the summer.
Even when pruning is done correctly, weather can still affect flowering. A late spring freeze may damage flower buds on old wood before they open. In those years, the shrub may lose most or all of its spring bloom display. Reblooming hydrangeas often recover by producing some flowers on new growth later in summer, although this second flush is usually less dramatic than the abundant spring show.
By identifying whether a hydrangea blooms on old or new wood, pruning only when necessary, and recognizing the effects of late spring freezes, gardeners can greatly improve their chances of enjoying beautiful hydrangea blooms season after season.
Related Videos:
Common Hydrangeas
How do I keep my Annabelle hydrangea from flopping on the ground?
Why is my hydrangea not blooming?
When should I prune my Hydrangea Paniculata?
Related Resources:
Hydrangea paniculata
Hydrangeas
Pruning hydrangeas for best bloom