What is a killing freeze (hard freeze)?
A killing freeze is when temperatures fall to or below 28ºF for at least a week. Most trees can survive brief periods of 32ºF. The killing freeze weather condition can kill a young fig tree if not protected. You can’t always make the best judgement when a freak cold blast comes down from Canada.
When autumn emerges, a tree will gradually drop it’s sap down to the base of the tree to help protect the branches from the Winter season, while it remains dormant. The problem that usually occurs is an early Spring during the month of March. At this moment, the weather warms up and the tree begins to leaf out as the sap returns to the branches.
As the Spring season emerges, the climate goes through a thawing/freeze period. Sometimes when the month of April approaches, a killing freeze could drop down suddenly. So, it can be difficult to judge when to unwrap your young tree.
Killing freeze from experience
I once had a situation in Connecticut where I had a 3 year old tree that suffered from a killing freeze in the month of April. All the branches died off down to the trunk of the tree, but because it had a very deep tap root, it sprung back to life in June where the new trunk system grew to 6 feet in 3 weeks. The following Fall, I wrapped the tree to protect the new growth. If you have a similar situation with a shallow tap root, there’s less of a chance that your young tree will survive. If you want to learn more about wrapping your tree for Winter storage, then visit my Outside Living page and see suggestion number 4 on Winterizing.