Whether or not hydrangeas need protection depends on how cold the winter temperatures drop. If the air temperature doesn't go below 0 degrees (zone 7) there is no need for winter protection. In colder climates, wrap or completely cover marginally hardy hydrangeas.
During the winter, make a DIY A-frame wire cage out of burlap and chicken wire to protect your hydrangea plant. This cage will protect it from winter winds, heavy snowfall, and cold temperatures.
In the winter too! Luckily, hydrangeas can tolerate some cold and are frost resistant due to their origins in Asia. But beware of severe (night) frost. Hydrangeas can survive the frost, but the buds can be damaged.
Keep Them Cozy. Whether or not hydrangeas need protection depends on how cold the winter temperatures drop. If the air temperature doesn't go below 0 degrees (zone 7) there is no need for winter protection. In colder climates, wrap or completely cover marginally hardy hydrangeas.
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
The hardiness zones for H. macrophylla are 6 to 9. Effectively, a hydrangea should be able to sustain a temperature of minus-10 degrees. But in the real world, temperatures as low as 12 degrees — and late fall or early spring freezes — may reduce the flowering capability of this hydrangea.
Cold tolerance varies with species, with some hardy to -15°F (-26°C). Popular bigleaf hydrangeas are often injured by winter temperatures below 10°F (-12°C).
While some plants bloom on new growth, others primarily set flower buds on old wood. Regardless, it is best to wait to prune all hydrangeas until spring. In the fall, hydrangeas (and all trees and shrubs) are in the process of going dormant. They do not produce very much new growth until the following spring.
If it stays cold for more than one night, can I keep my plants covered, or should I remove the coverings at some point? A. Our recommendation would be to remove the cold protection covering once temperatures are above 32 degrees.
Frost and cold can harm a Hydrangea, but thankfully, these plants are relatively hardy. Though it may affect this year's blooms, if pruned appropriately, Hydrangeas damaged by frost will most likely return to their old selves with a little bit of TLC.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon. The reblooming Endless Summer® Hydrangea series prefers part shade. These include BloomStruck®, Endless Summer®, Blushing Bride®, and Twist-n-Shout®.
Most hydrangeas prefer only morning sun. Yet one type of hydrangea can soak up the sun all day: the panicle hydrangea. While they can stand the sun, these do just fine in partial shade, too. Plus, panicle hydrangeas are the hardiest hydrangeas.
Paniculata and smoothleaf hydrangeas are generally very cold hardy, as are oakleaf hydrangeas and climbing hydrangeas, so these varieties don't usually need additional winter protection. Macrophylla hydrangeas, however, are a different story.
Some varieties, like smooth hydrangea (“Annabelle”) and panicle, or PG hydrangea, are very cold-hardy and bloom on new wood. If these are the species in your garden, you don't have to worry about winter kill on hydrangea. They don't need protection unless the temperature dips below negative 30 degrees F.
Hydrangeas don't look very nice in the winter. And they look even worse in the Spring! The old branches look dead at the end of winter (even though they're almost always just dormant); and they are unattractive for a while.
Typically, only a trimming is needed to maintain shape, size, and a healthy plant by cutting out dead, diseased, or broken branches. Otherwise, harsh pruning should be avoided. Trimming should be done immediately after flowering stops in summer, but no later than August 1.
Leaving the old flower heads on the plants will also add some interest to the winter landscape. It's best to save hydrangea pruning chores until spring or summer after plants bloom (don't worry, the new growth will soon hide any dead stems from the following year).
Foliage that has been frost damaged will turn purple/reddish. It may wilt or collapse. In a freeze, the stems, buds and foliage can turn black and dry looking. If you have experienced a frost or unexpected late freeze after your hydrangea have put on fresh new growth, it should be obvious that this is the problem.
Frost cloth is a commercially woven fabric that is light enough to allow air flow and light penetration, but thick enough to help retain warmth from the soil and protect the plant from frost. Always use frost cloth designed for covering plants.