November means fall is in full swing. The leaves of our trees begin to turn color and then fall to the ground making the ground colorful and giving it that characteristic “crunch” when you walk on the lawn. Why do some trees take so long to drop their leaves in the fall? And why do some hold onto the leaves throughout the entire winter? Finally, what do you do with the leaves when they fall to the ground?
Leaves fall to the ground in the fall to remove living material for the winter months. During the winter evergreen trees continue to transpire which can sometimes cause winter desiccation and browning on the needles if they lose more water than they take in. Deciduous trees lose their leaves to reduce the amount of living material necessary to support during the winter months and to reduce winter desiccation.
Each tree differs on how fast they lose their leaves. This is dependent on both the genetics of the tree and the environmental conditions they have faced this year. Two trees of the same species can lose their leaves at different times of the year based on the environment that is specifically surrounding that tree, or the microclimate. The environmental factors that affect when trees lose their leaves include prolonged drought, disease and insect pests, sunlight exposure, day length, colder air temperatures, frost timing, winds, soil, and water differences, according to Ted Griess, UNL Extension Horticulture Assistant. On years with extraordinarily hot and dry summers, the leaves tend to turn to fall color and drop off the tree much earlier than years of normal or cooler and wetter conditions throughout the summer.
Some trees, especially pin oak trees, hold onto their dead leaves throughout the entire winter and don’t lose the leaves produced this year until new leaves begin next spring. There is nothing wrong with this, it is a natural occurrence for some tree species.
Now that the leaves are falling, what do we do with them? It is not good for the lawn to leave the fallen leaves on the turf for the winter months. The leaves that fall can become matted on the grass and suffocate the lawn underneath. So, it is important to remove leaves from the lawn in the fall. This can be done with a rake or with a lawnmower. You can use the lawnmower to break up the leaves so that they go down into the turf and won’t suffocate it. You can also use the lawn mower to bag up all of the leaves as they fall. Mulching the leaves into the lawn will not add a thatch layer to your lawn. The leaves break down quickly and will not be a problem. Either way you do it, with a rake or a lawnmower, make sure that you get the leaves off of the lawn before winter.
After you have finished mowing the last time for the season, and have mowed up all your tree leaves, you should prepare your lawn mower for winter. Clean up the lawn mower and be sure to get all the grass off the blades and off of the underside of the deck. It may also be a good idea to sharpen the blades before you put it away for the winter so you don’t have to do that in the spring before you get started mowing.