Oakleaf hydrangeas (Hydrangea quercifolia) are prized for their showy cone-shaped blooms and attractive foliage. Their leaves turn purplish-red in fall, providing great color in the garden. But as winter approaches, many gardeners wonder if oakleaf hydrangeas lose their leaves as the weather turns cold.
The Short Answer
Yes, oakleaf hydrangeas do lose their leaves in winter. They are deciduous shrubs, meaning they drop all their leaves once a year before going dormant for the winter. This is a natural part of their growth cycle and helps the plant conserve energy when sunlight and warmth are scarce.
Why Oakleaf Hydrangeas Lose Their Leaves
All deciduous trees and shrubs native to climates with cold winters drop their leaves in fall and remain leafless until spring. This allows the plants to go into dormancy to survive freezing temperatures, snow, and ice.
If oakleaf hydrangeas kept their leaves through winter, the leaves would suffer freeze damage. They could also promote excessive moisture loss and cause the shrubs to dry out in winter winds.
Shedding leaves allows oakleaf hydrangeas to seal off areas of new growth called leaf buds. This protects the buds from winter damage. It also enables the plant to conserve moisture and energy by suspending photosynthesis and growth during the cold months.
The Leaf Drop Process
Oakleaf hydrangeas begin preparing for winter in fall as daylight hours shorten. The chlorophyll in the leaves breaks down, allowing other pigments like anthocyanins to show through. This transforms the leaves from green to rich red and purple hues.
At the base of each leaf stem, a special layer of cells called the abscission layer starts to form. This weakens the connection between the leaf and the stem. Cooler temperatures and shorter days signal the leaf to seal off the abscission layer and detach from the shrub.
Most oakleaf hydrangea leaves drop in late fall. Some stubborn leaves may remain on the branches into early winter until a hard frost or wind and rain knock them off.
When Do Oakleaf Hydrangeas Drop Their Leaves?
Oakleaf hydrangeas typically start dropping their leaves in late October or November. The precise timing depends on the climate and weather patterns each year.
In colder northern zones like USDA Zone 5 and cooler areas of Zone 6, oakleaf hydrangea leaves often begin changing color and falling in early to mid-October. The drop progresses as nights dip into the 30s and 40s Fahrenheit.
In warmer southern zones like Zone 7 and warmer areas of Zone 6, the leaves may stay green a week or two longer. Leaf drop usually starts between late October and mid-November and finishes by early December at the latest.
The shrubs drop most of their leaves within 2-3 weeks after the abscission process begins. Severe cold snaps or heavy snow and ice can strip all the leaves suddenly.
Factors That Influence Leaf Drop
Several environmental factors influence when oakleaf hydrangeas shed their leaves each year:
- Photoperiod – Shortening daylight hours initiate leaf senescence and abscission.
- Temperature – Sustained cold temperatures and frost hasten leaf drop.
- Precipitation – Heavy rain and wind strip leaves from branches.
- Geography – Leaves drop earlier in colder climates up north.
- Individual variation – Some plants drop leaves a bit earlier or later.
What Oakleaf Hydrangeas Look Like in Winter
Once oakleaf hydrangeas drop their leaves in late fall, the shrubs remain leafless until new leaves emerge in spring. Some dried leaf remnants may cling to the branches over winter.
The bare winter framework showcases the shrub’s exfoliating bark. On older stems, the bark peels away in thin cinnamon-colored strips, revealing an attractive underlayer of orange inner bark.
During winter dormancy, oakleaf hydrangea buds are naked and exposed. Flower buds for the next year’s blooms form at the tips of stems. Leaf buds contain the beginnings of next year’s foliage.
The large, showy flower heads also remain on the shrubs after the blooms fade. These dried hydrangea flowers persist through winter, providing visual interest until new growth appears in spring.
Do All Hydrangeas Lose Their Leaves?
All hydrangeas native to areas with cold winters are deciduous and lose their leaves annually. Examples include:
| Hydrangea Species | Leaf Loss |
|---|---|
| Oakleaf hydrangea | Loses leaves |
| Smooth hydrangea | Loses leaves |
| Panicle hydrangea | Loses leaves |
| Mountain hydrangea | Loses leaves |
| Peewee hydrangea | Loses leaves |
On the other hand, some hydrangea species like bigleaf (H. macrophylla) and climbing hydrangea (H. anomala subsp. petiolaris) can keep their leaves or retain some leaves through winter in mild climates. These species are native to more temperate Asian woodlands.
Caring for Leafless Oakleaf Hydrangeas
Oakleaf hydrangeas require little care while leafless. Avoid pruning or applying fertilizer during winter dormancy. Focus on protecting the shrubs until spring growth resumes.
Leave Spent Flowers on the Plant
The dried blossoms left on the plant provide winter interest and serve as insulation for emerging buds. Remove only spent blooms that have turned brown and papery.
Water During Extended Dry Spells
Water dormant oakleaf hydrangeas if winter and early spring are unusually dry. Deep water once a month during winter thaws if rainfall is less than 1 inch per week.
Mulch Around the Roots
Apply 2-3 inches of shredded bark, leaves, pine needles or other organic mulch around the base of the shrubs. This insulates roots and retains soil moisture.
Protect from Heavy Snow or Ice
Gently knock off accumulated snow or ice from branches to avoid limb breakage, especially on top-heavy mophead forms. Use brooms to sweep off snow.
Prevent Rabbit and Rodent Damage
Wrap trunks of young trees with hardware cloth or wire mesh to protect from hungry rabbits and rodents.
When Do New Leaves Emerge in Spring?
Oakleaf hydrangeas break dormancy and produce new leaves in spring once temperatures warm and daylight lengthens. In USDA Zone 5, new leaves usually emerge by mid to late April. In warmer Zones 6 and 7, expect new leaves by early to mid-April.
The exact timing depends on weather and individual plants. Leaves may emerge earlier after mild winters or later following harsh winters.
New leaves first appear from the leaf buds as furled shoots tinged with red. The leaves unfurl and expand to full size within a week or two after emerging.
Signs that New Growth is About to Begin
Watch for these clues that oakleaf hydrangeas are poised to leaf out in spring:
- Flower buds swell and elongate.
- Leaf buds plump up and enlarge.
- Branches look fuller as new growth develops inside buds.
- Reddish leaf shoots peek out from buds.
In Summary
Oakleaf hydrangeas shed their leaves as an adaptation to survive cold, inactive winters. Leaves turn bright colors in fall before dropping. The deciduous shrubs remain leafless all winter long. Then new foliage emerges again each spring to support another year of growth and spectacular blooms.
Knowing oakleaf hydrangeas lose leaves annually helps gardeners understand this normal winter appearance. With proper care focused on protection, hydrangeas will revive beautifully when warm temperatures return.