Protecting Your Japanese Maple During A Cold Snap
In this Episode of the Mr. Maple Show, Tim and Matt talk about cold snaps and what you should do to protect your Japanese Maples.
What is a cold snap?
When the weather gets cold after a very warm period of time, it is considered a cold snap. In Western North Carolina, where we are located, we often get these periods in spring when we're starting to acclimate and then go back down to cooler temperatures.
During the spring, temperatures can reach all the way up to 70°F, which means our plants start pushing growth and/or begin active root growth as well as trunk sap. Sometimes the weather forecast calls for colder temperatures, for example 16°F. If your weather has already been at 16°F, then it does not apply to you. It only applies if it has been warm and suddenly changes.
The more extreme changes of weather are times that you're going to need to protect your Japanese Maples. You're going to need to take more caution to ensure that there aren't any damages from the activation of that tree. At our nursery, we always encourage that you be prepared. As the old adage goes, an ounce of prevention is better than a pound of cure. It's always better to be stay ahead of those cold snaps, which is something that we here in Western NC are always conscious of.
What we love to see in the spring is a long, consistent incline of weather; what we don't like to see is erratic ups and downs. Here at our nursery we will put our heaters in our cold frames up to help with the temperature, which is the only time we heat. We like to keep our greenhouse doors open 99% of the winter unless there is an extreme change so that our trees will shut down properly and become as dormant as possible for the winter.
You do not want your trees to be active during your extreme changes, so there are things that we recommend.
One thing that you can do to help your Japanese Maples during potential cold snaps is to make sure that you don't over fertilize your trees. This helps them to grow better cell walls and make them more durable during the cold snaps. We always try to grow our trees at a moderate pace so that their cell walls don't become stretched. We go low on the Nitrogen number and we do not fertilize early in the season.
If your plant is dormant and hasn't broken bud, there's not really anything that you need to do since the plant is still dormant and therefore will be equipped to handle the cold weather than a plant that is in leaf. One important thing is to make sure you don't give your trees a false spring, which is bringing them inside long enough to get them in leaf and then bringing them outside too early.
If your trees are in a container and have broken bud already, we recommend that you bring them inside an unheated garage or unheated shed. You should get your trees back outside as soon as possible after the cold snap. We hear some people complain that their trees don't look too good after two weeks inside, and that is due to the trees leafing out without correct airflow.
One of the most detrimental things is a clear plastic bag. If your plants are in the ground and are beginning to leaf out, do not cover them with plastic (this includes plastic pots over the top of the tree). If you cover them with plastic, the entire plant will suffer damage. When a tree is covered with a plastic bag, it essentially microwaves the tree. It forces more foliage out and therefore, more foliage is damaged. We recommend bed sheets or a frost cloth since they do not lock heat in.
What if I didn't protect my plants in time for the cold snap?
If you missed covering your plants for a cold snap, the best thing to do once the cold snap is over is watering. During a cold snap, plants tend to dehydrate just like they would in the summer when the temperatures are really high. The plants will also need something to push them along and give them energy, so liquid Miracle-Gro can help, but mainly water since it is best not to push the trees into growing too soon.
Additional tags: Japanese Maples, cold snaps, Protecting Your Japanese Maple During a Cold Snap, MrMaple Show, MrMaple.com