Hydrangeas are popular flowering shrubs sought after for their large, dramatic blooms. Whether these plants are low maintenance depends heavily on the specific variety and the climate in which it is grown. For many common types, routine care is minimal once basic environmental needs are met, but the periodic task of pruning can seem complicated, leading some to view them as high maintenance.
Meeting Fundamental Environmental Needs
Hydrangeas thrive when their fundamental needs for light, water, and soil are consistently met. The ideal location for most varieties receives bright morning sunlight followed by afternoon shade, especially in warmer climates. Intense midday sun can scorch the foliage and cause rapid wilting. Too much shade will limit the plant’s energy production and reduce the number of blooms it produces.
These shrubs require consistent moisture. Deep watering one to two times per week is necessary, ensuring the top four to six inches of soil remain evenly moist but never waterlogged, as poor drainage can lead to root issues. Applying a two to three-inch layer of organic mulch around the base helps by stabilizing the soil temperature and reducing water evaporation.
The soil should be rich in organic matter and well-draining to prevent the roots from sitting in soggy conditions. For bigleaf hydrangeas (Hydrangea macrophylla), the soil’s pH level is a unique consideration, as it directly influences the flower color. A soil pH below 6.0 allows the plant to absorb aluminum, resulting in blue blooms, while a pH above 6.5 leads to pink flowers.
Simplified Pruning Guidance
Pruning is often the biggest source of confusion, but the process can be simplified by knowing the plant’s blooming habit. The most important distinction is whether the variety blooms on “old wood” or “new wood.” Old wood refers to the stems that grew during the previous summer, and the flower buds for the next season form on these stems by late summer or early fall.
Varieties like bigleaf (H. macrophylla) and oakleaf (H. quercifolia) hydrangeas bloom on old wood, meaning they should only be pruned immediately after the flowers fade in the summer. Pruning these shrubs in late winter or spring will remove the developing flower buds, resulting in a year without blooms. The objective of this pruning is to remove spent flowers or up to one-third of the oldest, weakest stems to encourage vigorous new growth.
Panicle (H. paniculata) and smooth (H. arborescens) hydrangeas bloom on new wood, which are stems that grow in the current season. These types can be pruned back in late winter or early spring before new growth begins, without sacrificing the year’s flower display. For these varieties, pruning is simply a matter of shaping the plant or reducing its size, and they require less precision for a guaranteed bloom.
When Hydrangeas Fail to Bloom
A failure to bloom, sometimes called “blind wood,” is a common problem, but the causes are straightforward and addressable. The most frequent culprit is improper pruning timing on old wood bloomers, where the flower buds were accidentally cut off during late winter or spring. This mistake requires only a change in the pruning schedule for the following year to restore flowering.
Another primary reason for a lack of flowers is winter damage, particularly for bigleaf hydrangeas in colder regions. A late-season frost in the spring can kill the tender, emerging flower buds on old wood, even if the rest of the plant appears healthy. Protecting these varieties from deep freezes with burlap or other coverings helps preserve the delicate buds.
Finally, applying a fertilizer that is too high in nitrogen encourages excessive foliage growth at the expense of flower production. Switching to a more balanced fertilizer can redirect the plant’s energy toward producing blooms.