Thankfully, the plant's roots are hardy enough to last through intense cold. The roots can live through conditions as low as -18° F. On these tough plants, the wood and root structures are well-insulated and not likely to experience significant harm.
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.
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.
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.
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.
The Bottom Line. If extreme cold weather has damaged your Hydrangeas, they will most likely recover. These plants are hardy, and though they may not rebloom this year, as long as you prune back the damage done, you should start to see its beautiful flowers the following spring.
Important: Since hydrangeas tend to set their blooms on the ends of the branches, it is important to keep these covered all winter. Most insulating materials will pack down somewhat during the winter and expose the branch tips, so the material must either be replaced or secured in place.
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.
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.
Absolutely! Hydrangeas are hardy shrubs that can survive a winter freeze. As long as the shrub isn't subjected to repeated below zero temperatures, most species of hydrangea will be just fine through colder weather.
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.
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.
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.
Hydrangeas that bloom on new wood can be safely pruned in late fall once the plants have gone dormant or in early spring. Next year's flower buds won't be formed until late spring the same year they bloom, so there is no risk of removing the buds if you prune in fall or spring.
Frigid winter temperatures, as well as winter winds, can cause winter kill on hydrangeas. The low winter temperatures can kill the plant, or they might die because of drying out caused by winds.
The primary reasons hydrangeas don't bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer. Hydrangea varieties can be of the type that blooms on old wood, new wood or both. Old wood is the current year's growth and new wood is next year's (spring) growth.
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®.
First, add a 1/4 cup of sugar to the room temperature water in the vase. The sugar helps feed the stems and increases the life of the cut flowers.
As rapid growers—averaging about 2 feet of growth per year—larger varieties of hydrangeas can reach up to 15 feet tall. Applicable in growing zones 3 to 9, hydrangeas are a low maintenance plant that will return year after year with proper care.