How to Help Your Hydrangeas Survive Winter—and Produce Beautiful Blooms Next Year

Hydrangeas are known for their lush clusters of beautiful blooms, which can blossom in both garden beds and flowerpots. While these flowers are a sight to behold in the summer, as the colder months approach, you may find yourself wondering when to overwinter them. To help you keep these flowers happy and healthy, we gathered the best advice from the industry's top garden experts. Read on for their tips and tricks on how to keep hydrangeas alive all through the winter.

Do Hydrangeas Like the Cold?

Hydrangeas need the cold for their dormant period. “In the North, hydrangeas are able to get a longer sleep, resulting in fuller, more lush plants and vivid, vibrant blooms,” says Mary Rock, the general manager of Esposito Garden Center. For example, Vanilla Strawberry hydrangeas in North Florida aren’t as brilliant in color as ones grown in Pennsylvania.

When to Overwinter

Timing depends on the region you live in. According to Luke Jackson, the owner-manager of Jacksons Nurseries, if you're in a cool climate, then it's a good idea to start overwintering hydrangeas in late fall—ideally a few weeks before the first frost. In warmer climates (or hardiness zones 4 and above), then you'll only need to do light winterizing on the very coldest nights of the year. “Always keep an eye on the weather reports,” he says. “States with unpredictable weather can sometimes experience freezing temperatures much earlier than anticipated.”

Garden Hydrangeas

Hydrangeas planted in flower beds can stay there over the winter. “Plant relocation isn't necessary in any zone, as hydrangeas are very cold hardy,” says Rock. In many cases, simply mulching the base of the plant and giving it a deep drink of water before a hard freeze can be enough.

Apply Mulch

If your hydrangeas are outside and established in a garden bed, then make sure to apply a generous layer of good-quality mulch around the base. Jackson recommends doing this at the beginning of winter: “Mulch helps to insulate the roots, and adds an extra layer of protection during harsh frosts. It also helps preserve moisture and provides essential nutrients.”

Some varieties need more attention than others. “For Hydrangea macrophylla and quercifolia, use horticultural fleece or burlap to protect the flower buds during hard frosts,” he says. Secure the cover around the budding branches with gardening twine or string. Panicle and smooth hydrangeas, meanwhile, are exceptionally hardy and won't need as much attention.

Remember to Water

Hydrangeas tend to need more water. “It's important to give them one last thorough and deep water before the ground freezes," says Jackson. "Keep their compost slightly moist over the winter period." This will keep the plants strong until spring.

Protect from Harsh Winds

“If your hydrangea is not already protected from the wind by a building, fence, raised bed, or other trees or shrubs, then consider setting burlap or stakes up around it,” says Jackson. However, any relocation should be done in fall. This is the best time to safely dig up the plant and move it to a more sheltered spot—ideally one protected by shrubs like rhododendrons, azaleas, or spruce.

Potted Hydrangeas

Always move potted hydrangeas indoors before the frost. Even a garage or shed can provide more protection than being left on an uncovered porch or deck. This method is especially important for hydrangeas grown in porous containers, like unglazed terracotta and clay pots, which Jackson says offer a lower level of frost protection for roots.

Provide Sunlight

Remember to provide your potted indoor hydrangeas with bright, high quality, indirect light at all times. “The indoor light quality will generally be lower than outdoors,” says Jackson. “So the plants are best positioned next to an east-facing window to receive morning sunlight.” Alternatively, placing them near a south-facing window lets them receive sunlight throughout the day.

Prevent Drafts and Overheating

Indoor hydrangeas won’t like cold drafts or being placed by heat sources. For example, if you normally have your hydrangea on a table close to the entryway, then move it somewhere else where it won’t catch cold when the front door opens. “Also, avoid having your hydrangea too close to radiators and open fires," says Jackson. "They will be vulnerable to drying out, especially when the heating is on during the winter.”

This is another reason why a cool, sheltered area like a garage is the best place for overwintering potted hydrangeas. “The location needs to be unheated," says Jackson. "You'll still want your plants to go dormant over the winter period. That way they'll be ready to fuel a fabulous display of flowers and foliage in the following year."

Pot with a Drainage Hole

Your selected flowerpot should have drainage holes, which will help keep your hydrangeas watered during winter—without the threat of root rot. Jackson suggests checking the compost’s moisture level at about three inches deep. “If it’s still dry to the touch at that depth, then give your plant a thorough water until you see water run out of the bottom," he says.

Wake Up Your Plant in the Spring

Hydrangeas will need warm temperatures to wake them from their winter sleep. “Aim for temperatures in the 80’s,” says Rock. Slowly raise the temperature in your home so as not to force the plant into shock—one solution is to place hydrangeas in a slightly warmer area of the house that receives more sunlight, which will gradually warm them up. Alternatively, you can use grow lights. “Grow lights can not only give the hydrangea the light source needed, but also add warmth to the plant to wake it from its sleep,” she says.