The walnut is troubled by late frosts
The walnut tree originally comes from
- from the Eastern Mediterranean,
- from the Balkan Peninsula and
- from Middle East and Central Asia.
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- Walnut tree: when is the right time to plant?
- Frost damage to the walnut tree - causes and treatment
In short: the walnut developed in warm climes.
Walnut trees were already cultivated in Germany in Roman times - but only in the (warmer) southwest. Overgrown walnut trees were (and are) mainly found in the mild winter regions of today's Federal Republic.
Given the origin of the walnut, it is not surprising that it is a frost-sensitive plant. The walnut tree does not particularly cope with late frosts.
The most dangerous times for the walnuts are April, May and June. During these months, walnut trees develop leaves and flowers. During this critical phase, temperatures just below freezing point are sufficient for frost damage to result.
“Late frosts” after early spring
There is also a special type of “late frost”: If spring sets in earlier than usual, if the temperatures rise early, the walnut tree feels stimulated - and is more likely to sprout. If a longer period of cold suddenly follows, the fresh shoots are exposed to frost without protection and damage is inevitable.
Recognize frozen walnut tree
It's easy to tell if a walnut tree has frozen to death. A frost-damaged plant shows up overnight
- black leaves and
- brownish to black flowers.
Saving a frozen walnut tree - how?
Depending on whether the leaves or flowers have frozen, you can take suitable measures to help your walnut tree to recover, or you have to rely on the pronounced self-healing power of the plant.
You are not completely powerless against frozen leaves. But you have almost no choice but to hope that your walnut tree will sprout again.
Watch the tree. After a few weeks, new shoots should begin. With the right fertilizer, you give the plant additional strength. Also, be sure to keep your tree well hydrated.
Important: After the late frost, the walnut tree MUST sprout leaves. He needs them to survive. Without leaves, the walnut dies.
Besides, it doesn't make sense to cut off frozen leaves. This would only result in open wounds, which the tree would need even more strength to heal. It is therefore advisable to leave the disposal of the frozen leaves to the wind.
Grafted walnut trees are an exception. In this case, you should cut off all frozen leaves after the frosty night. But leave the leaf stalks standing. A few days later, new shoots sprout from the eyes. Then attach the lead shoot. After a few more weeks, carefully cut off the frost-damaged shoot.
Frozen flowers can mean a complete loss of harvest. In late frosts, the male flowers are always affected (they usually come out four weeks before their female partners).
In this case, there is only a realistic chance of a harvest in autumn if another (healthy) walnut tree is nearby.
Prevent damage from late frosts
Adult, large walnut trees cannot be protected from late frosts. They are just too big. With smaller trees, however, you can work well with a fleece. At least this measure helps to limit the damage.
Note: By planting a late-growing variety, you reduce the risk factor “late frost” right from the start.