Hydrangeas enter dormancy during colder months, stopping above-ground growth and dropping leaves. Even without foliage, the root system remains alive and requires moisture to survive the winter season. Therefore, the answer to whether you water hydrangeas in winter is yes, but the method and frequency differ significantly from the active growing season. The goal of winter watering is purely to sustain the root structure until spring, not to fuel growth.
The Necessity of Winter Watering
The primary threat to hydrangeas in winter is desiccation, or drying out. Woody plants lose moisture through their stems and buds even when dormant, a process accelerated by cold winter winds. This effect, often called “winter burn,” draws water out faster than the roots can replace it, especially when the ground is frozen solid.
Water stored in the root system keeps plant tissues hydrated and prevents this moisture loss. If the roots dry out completely, the plant can suffer significant dieback or fail to produce new shoots in the spring. Winter watering is a protective measure focused on root health and survival, making well-hydrated plants more resilient against cold damage.
Monitoring Soil Moisture and Frequency
When the ground is not consistently frozen, watering must be done judiciously to avoid desiccation and root rot. In areas where the ground does not freeze, or during mid-winter thaws, hydrangeas benefit from deep but infrequent watering. A general guideline is to water about once a month if precipitation has been low.
To determine if the plant needs water, check the soil moisture several inches down, not just the surface. Use the “finger test” by pushing your finger or a trowel 4 to 6 inches into the soil near the plant’s base. If the soil feels dry at this depth, water deeply, allowing moisture to reach the entire root zone. Overwatering is dangerous in winter, as soggy soil can lead to root rot, which is often fatal to the dormant plant.
Transitioning In and Out of Dormancy
The timing of watering is crucial for preparing the plant for dormancy and awakening it for spring. In the fall, before the ground freezes solid, give the hydrangea a deep watering. This ensures the roots have a moisture reserve to draw upon during the coldest periods. Continue this deep watering until the soil surface is frozen hard.
As temperatures begin to rise consistently above freezing in late winter, gradually increase the watering frequency. This supports the initial development of new buds and shoots. Resume normal active growing season watering habits once the plant is actively putting on new leaves and the risk of a hard freeze has passed.