Hydrangeas have frozen to death: help with frost damage

Hydrangeas are those Stars in every cottage garden. The robust garden plants survive many a cold winter. However, hydrangeas can sometimes be frozen to death in spring. All measures for prevention and help are given below.

Hydrangeas very robust

Hydrangeas are usually one of the more robust garden plants. They are conditionally hardy and survive many periods of frost. However, they are very sensitive to late frosts that occur in the spring after the new shoots have emerged. Hydrangeas are particularly susceptible to this, as they planted the flowers for the coming gardening season in the previous year. It can quickly happen that the tender buds fall victim to the frost. In other words, they froze to death. These include farm hydrangeas (Hydrangea macrophylla) and plate hydrangeas (Hydrangea serrata). Frost damage to hydrangeas can be seen:

• on light brown to dark brown shoots
• Shoots often dry

Sometimes the perennials appear frozen after winter, but they are not. To be really sure whether the shoots are dead, simply scratch the bark lightly with the thumbnail. If it comes off easily and a green, juicy tissue appears underneath, there is still life in the shoots. On the other hand, a slightly yellowish-green discoloration to under the last pair of eyes indicates that the shoot has dried up and is dead.

Note: Shade-loving hydrangeas are less susceptible to frost damage in winter, like hydrangeas that prefer a sunny location.

Measures in spring

Normally, in the spring of a hydrangea, only the withered, old flowers just above the top pair of eyes are cut off. In the case of frozen shoots, however, only a complete cut back will usually help.
In addition:

• Cut back to the first living pair of buds
• completely remove the drive in the event of severe damage
• do not prune back too early
• optimal time at the end of February / beginning of March
• thin out the hydrangeas next to them

Sometimes it can also happen that a hydrangea is more severely damaged in very cold winters with strong frosts. However, this happens relatively less often. In this case, a complete cut should be made down to the ground. With a lot of luck and patience, the plant will then sprout again. However, there are differences in the individual species and varieties in terms of the number of flowers to be expected after pruning.

Hydrangea with flowers in the previous year

• these include plate hydrangeas (Hydrangea serrata), farmer's hydrangeas (H. macrophylla), velvet hydrangeas (H. sargentiana) and climbing hydrangeas (H. petiolaris)
• the more blatant the cut, the less the flowers
• with radical pruning, flowering fails completely in that year

Hydrangea with flowers on the "new" wood

• these include snowball hydrangeas (Hydrangea arborescens) and panicle hydrangeas (H. paniculata)
• Pruning does not affect the number of flowers
• Buds are always planted in the same year
• however, there must be one pair of eyes per shoot

However, if there are no longer any living shoots with a pair of buds, it is advisable to dig up the hydrangea and replace it with a new one.

Note: When buying, you should already pay attention to the winter hardiness of the corresponding hydrangea so as not to be surprised in the coming spring. The plant label provides information about the respective winter hardiness. In addition, advice from a specialist is advisable.

Late frosts are particularly dangerous

Especially after the new shoots, frosts in the months of April / May can severely damage the young and still soft shoots. If the temperature falls far below -5 ° C, then it is hardly possible to save this year's blooms. However, if only the young leaves are affected, they are simply removed. They are subsequently replaced by new ones. It is not necessary to cut back the shoots. However, it looks different when the shoot tips hang down. Then you have to use scissors and shorten the affected shoot to the next pair of living eyes. A light winter protection is recommended during this time.

Prevent frost damage

In order to avoid frost damage to hydrangeas in advance during the cold season, certain measures should be taken. It starts with the choice of location. This can already prevent damage. This also includes:

• Protection from cold easterly winds
• Avoid strong sunlight, especially in winter
• Sun favors early budding
• later frosts then cause major damage
• Do not cut off withered flower heads in autumn
• provide protection for underlying buds
• no pruning in autumn
• Remove dead wood, a source of rot, fungi and pathogens
• Shorten long protruding shoots, risk of snow breakage
• Stop nitrogen fertilization from July
• Organic fertilizer can be given until August
• optimal application of potash-based fertilizers such as patent potash
• thereby maturation and lignification of the shoots by winter
• Stop fertilizing completely from September
• water sufficiently in autumn
• Avoid waterlogging
• if the roots are damaged, the plant is more susceptible to frost damage

Tip: Administration of fertilizer rich in potash well into September increases the frost hardiness of the plants. The nutrients strengthen the cell walls and at the same time lower the freezing point of the existing cell water. Comfrey manure is also ideally suited as autumn fertilization in addition to Patentkali.

Apply suitable winter protection

Although hydrangeas are relatively winter-proof, it is advisable to apply additional winter protection, especially in rough areas. Such winter protection is particularly important for young plants that were only planted in the spring of the same year. These are not yet deeply rooted during the short time and frost damage can occur more quickly here. Before the onset of winter, various protective measures should now be taken:

• Mulch root slices
• to do this, apply a 10 cm high layer of leaves
• cover these with fir twigs
• Pile up the root neck 10 to 20 cm high
• suitable for garden or compost soil
• Cover shoots with breathable winter fleece
• alternatively lay wire mesh loosely over shoots
• then cover with fir twigs
• Another alternative: stick sticks around the plant
• Hydrangea has to be able to breathe
• apply winter protection again after pruning if there is a risk of ground frost
• Completely remove winter protection no later than mid-May
• otherwise fungal infestation is favored by rising temperatures

Tip: Do not use foils or other airtight materials. Condensation forms underneath and rot quickly occurs.

Winter protection for container plants

Of course, a hydrangea in the tub also needs adequate winter protection during the cold season. Otherwise it can quickly happen that the shoots or even the entire plant will freeze to death in spring. The following precautions should be taken:

• Installation of the bucket in a sheltered place
• Place the bucket on a frost-proof surface
• suitable wooden board or styrofoam
• Cover the root disc with leaves and fir branches over it
• Cover the bucket with bubble wrap, coconut mats or a jute sack
• Cover the shoots with special winter fleece
• It is better to overwinter buckets with a diameter of less than 35 cm in the house without frost
• temperatures between 3 and 5 ° C
• cool temperatures favor flower formation

Note: Not only can frost damage a hydrangea, the drought stress in winter has an even worse effect on the plant. Sunshine, cold frosts with low temperatures and of course a lack of snow cover can quickly lead to the root ball drying out. It is therefore advisable to water the plant a little on frost-free days.

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