Rescuing frostbitten hydrangeas: How it's done

The smooth hydrangea (Hydrangea arborescens) is frost resistant and survives cold winters without any problems. The shoots are trimmed in spring and only a few pairs of eyes remain.

Particularly cold winters can cause serious damage to hydrangeas. Flowering shrubs have suffered greatly in recent years, especially in regions in eastern Germany. Many of them are completely frostbitten. If you live in a region with rather cold winters, you should therefore make sure that the place in the garden is as sheltered as possible when planting the hydrangeas. This way you can possibly prevent frost damage to the plants.

Choose a spot that is protected from the easterly winds, which are particularly cold in winter. The hydrangea should also not be exposed to strong sunlight in winter. Although the sun warms, it also encourages hydrangeas to form new shoots prematurely. If frost then occurs, these young shoots are particularly badly damaged.

You can prevent frost damage to hydrangeas with various measures. In the fall, when you are winterizing your garden and preparing the other plants for the cold season, place winter protection on the hydrangeas.

Especially protect young plants in the garden. If they were only planted in spring, they have not yet been able to root very deeply and need particularly good protection from frost in their first winter.

Cover the hydrangea shrub base with a thick layer of foliage. The leaves keep the cold away from the roots. Cover the leaves with pine branches. A strong wind thus cannot blow it away. Also protect the shoots with pine branches. Alternatively, you can wrap the shrubs in a breathable winter fleece. You can also build a plant cover in the form of a teepee for sensitive plants.
 

The bigleaf hydrangea is a subshrub. Their shoots therefore do not become completely woody in autumn. These plants are thus particularly sensitive to frost in winter. That's why they usually freeze back every winter.

The degree to which the plant freezes back will depend on the severity of the frost. If it was mild in winter, often only the non-woody areas of the hydrangea are frozen. After harsh winters, frost damage is often found on the woody parts of the hydrangeas.

You can tell that shoots have frostbitten by their color: Pale brown to dark brown bark is a pretty sure sign. If this part of the plant is frostbitten, the bark often dries up. If you are unsure, scratch the shoot lightly with your fingernail. If you see green tissue underneath, there is still life in the shoot. If it is dry and the tissue is also dry and a yellow-green color appears after scratching, the shoot is frostbitten.

With big leaf and Hydrangea macrophylla, you actually only cut off the old flowers in spring. Use sharp secateurs for this. The EasyPrune from Bosch, for example, is well suited for this. It is power-enhanced and cuts particularly easily and cleanly. For stronger shoots, use a saw such as the KEO cordless garden saw from Bosch.

Always cut off old flowers above the top pair of vital buds. If shoots are frostbitten, cut them back to the healthy wood. If there is particularly severe frost damage, you may have to remove them completely.

If the hydrangea has suffered extremely severe frost damage in the winter, it may not bloom in the summer. This is because the buds that were planted the previous year froze in winter.

Some varieties, such as Endless Summer, form new buds until summer even after they have been cut back close to the ground. These varieties are called remontant. Despite the pruning, they still bloom on the so-called “new wood” in the summer of the same year.

In very extreme frost, the frost damage to the hydrangea can be so severe that the entire plant dies. Then dig up the shrub in spring and replace it with a new plant of your choice. Maybe it will be a hydrangea again. But you can also plant another flowering shrub.

Would you like more information about plant pruning? Then read more about pruning shrubs. You can find a pruning calendar, the different types of cuts and instructions for correct pruning here.

If there is severe cold again in April or May, i.e. after the hydrangeas have sprouted, with overnight frost, the plants often suffer particularly severe damage. The young shoots are still soft and therefore very sensitive.

If frost is forecast for the night, you should protect your hydrangeas again with a warming fleece. If that wasn't possible, take a close look at the damaged parts of the plant. Often only the young leaves are damaged, but not the shoots. In this case no pruning is necessary. The hydrangea replaces the frostbitten leaves with new ones throughout the year.

However, if the shoot tips are also frostbitten and hang limply, cut back the main shoots. Prune them back to the next pair of intact buds. On the big leaf and macrophylla hydrangea, the buds further down on the shoots are usually leaf or shoot buds. They don't produce flowers. With remontant varieties of hydrangea, you can still expect flowers in the same year even after a late pruning. However, you have to be patient until mid/end of August.

If you want to know more about when you should do what kind of work in the garden, you can find out the best times for all the important tasks in our Gardening Calendar.