Can hydrangeas survive winter in cold climates?
Written by
Michael Sullivan
Reviewed by
Prof. Martin Thorne, Ph.D.With appropriate precautions in freezing weather, hydrangeas can be winterized for cold regions and survive freezing winters. The variety of hydrangea you have chosen is a crucial factor in determining its hardiness, and how you will prepare it will depend on your USDA zone. I have successfully overwintered hydrangeas in zone 3 by using deep mulch and windbreaks. Timing is crucial in this process, as it is essential to winterize them after the first hard frost but before the ambient temperature drops to 20°F (-7°C).
Mulching Methods
- Apply 6-12 inches of coarse mulch like straw or oak leaves around the base
- Create a mound extending 18 inches from the stem to insulate roots
- Avoid packing mulch against stems to prevent rodent damage and rot
Shrub Wrapping
- Wrap plants with burlap secured to wooden stakes before snowfall
- Leave air space between fabric and foliage to prevent freezing contact
- Use breathable materials avoiding plastics that cause condensation
Container Care
- Move pots to unheated garages when temperatures drop below 25°F (-4°C)
- Water monthly during dormancy to prevent desiccation of roots
- Wrap containers with bubble wrap or burlap for extra insulation
Spring Transition
- Remove mulch gradually as temperatures rise above 40°F (4°C) consistently
- Prune winter damage only after new growth appears in late spring
- Apply balanced fertilizer once active growth resumes
Preparations for winter start six weeks before the first frost. Fertilization should stop in late summer to harden off new growth. Supply deep water before the ground freezes to give plants moisture reserves. Remove fallen leaves as a means of stopping disease from overwintering in last year's leaf debris. If possible, wrap the stems of young plants with tree guards to protect them from rodent damage. These steps will help prepare the plants to withstand the winter.
Keep an eye on your plants through the winter thaws. Look for signs of dehydration, such as shriveled buds. If the soil is dry and the temperatures go above freezing, then water the plants. Inspect the wraps for damage from ice or animals. If a significant amount of snow has melted, add extra mulch to protect the plants. If there are warm periods, consider whether it is worth unwrapping the plants as they start to grow too early.
Spring evaluation establishes current recovery needs. I evaluate winter damage until around the middle of spring, when the air has warmed considerably, here in Ohio. You can scratch the stems to see if there is a green cambium layer under the bark. You will be pruning dead wood until you reach a live bud. My panicle hydrangeas often look dead, but then rebound into vigorous new growth from the base when they experience complete dieback. Winter recovery usually requires patience.
Microclimate placement enhances the chances for survival. Place hydrangeas near a south-facing wall to capture a little bit of extra radiant heat on some of the colder fall and spring evenings. Be sure not to site them in low areas where cold air settles. An evergreen shrub will provide some protection from wind and cold. In my Minnesota garden, hydrangeas located near the foundation of my house have withstood the elements better than the exposed specimens during polar vortex periods. Your specific location is often as important as any wind protection you may have.
Read the full article: How to Care for Hydrangea: Complete Growing Guide
