The walnut tree is a frost-sensitive plant that is particularly at risk of damage during late frosts. In this guide you will find out everything you need to know about frost damage to walnuts.
How do you save a walnut tree from frost damage?
When frost damage occurs on walnut trees, black leaves and brownish to black flowers appear. To save the tree, add fertilizer, give it plenty of fluids and give it time for new growth. However, on grafted trees, remove frozen leaves and attach the leading shoot.
Late frosts damage the walnut tree
The walnut tree originally developed in warm climates. This is why the plant is so sensitive to frost. Late frosts are primarily problematic.
Walnut trees produce leaves and flowers in the months of April, May and June. If frost occurs at this time, frost damage will result.
Note: Temperatures just below freezing are sufficient in this case.
“Late frosts” after early spring
In addition to the classic late frosts, there is another critical scenario that relates to the first appearance of spring: If it sets in prematurely and ensures warm temperatures early, this encourages the walnut to sprout earlier.
That wouldn't be a drama in itself, on the contrary. But: If another prolonged cold period suddenly follows, the tree's fresh shoots hardly stand a chance.
How to recognize frost damage to the walnut
A frost-damaged walnut tree shows black leaves and brownish to black flowers overnight.
How to Save a Frost Damaged Walnut Tree
You have to rely as much as possible on the self-healing powers of your walnut tree and you only have a few options to actively help it.
What to do if leaves are damaged
- Watch your walnut. After a few weeks it should start producing new growth.
- Do NOT cut off the frozen leaves, otherwise the tree will also have to heal open wounds (unnecessary loss of strength). The wind will carry the leaves away.
- Provide the tree with suitable fertilizer (€9.00 on Amazon) to give it additional strength.
- Add enough liquid to the walnut.
Attention: New growth is extremely important. Without leaves the tree dies.
Note about grafted walnut trees: They are an exception when it comes to cutting off the leaves:
- Cut off all frozen leaves immediately after the night of frost.
- Leave the petioles.
- A few days later, new shoots sprout from the eyes.
- Then connect the leading shoot.
- After a few weeks, cut off the frost-damaged shoot.
What to do if flowers are damaged
If the flowers are frozen, you are powerless and have to expect a complete loss of harvest - unless there is another (he althy) walnut tree nearby.