Our fall leaf display was astounding in recent weeks in many parts of the Lakelands. Many people often ask the question, “Why do the leaves turn colors in autumn?” There are the biochemical answers which are too long for this column, or the more simple answer; deciduous trees have a biological system that shuts down the leaves in the fall as part of the process to shed them for winter.
Growing leaves get their green color from chloroplasts which are part of the photosynthesis process that plants use to take sunlight and convert it into simple sugars, which is used to nourish the plant. Deciduous tree foliage is susceptible to freezing temperatures, so trees evolved methods to recognize the signs of fall and eventual freezes. This allows trees to remove useful nutrients from leaves and cut off the leaves naturally by abscission before freezing weather kills them.
Shorter days, cooler temperatures and less sunlight reaching the leaves stimulate trees to start the process of closing up for the winter. (More sophisticated explanations) can be found in HGIC Bulletin 1029, Color Changes in Autumn Leaves at clemson.edu/extension/hgic/plants/landscape/trees/hgic1029.html.
Using all those new leaves
After several weeks of brilliant foliage displays in the Lakelands recent rains have helped wash most of the leaves down to the ground. Our display was better than average this year, but why I cannot say for sure. One possibility was that our first frosts were not until mid-November which allowed leaves more time to completely change colors on trees such as maples, hickories, crape myrtles, and oaks.
Wet leaves are not fun to work with but leaf raking needs to be done on turf areas, driveways and walks. There are many great uses for this free organic matter, but too many people will bag them and send them to the landfill. Bagging is a great financial benefit for the companies that make large black plastic bags, but throws away a useful resource for the gardener.
Unfortunately, next spring when they refurbish an old flower bed, start a new one, or need to add mulch around trees and shrubs, they will purchase expensive mulches from local businesses. Even if you prefer ground bark, pine straw or colored mulch you can use leaves, or ground leaves under the mulch. I often rake away my pine straw mulch, add several inches of leaves, and put them back on top with additional pine needle mulch as needed.
Volume of leaves can be reduced by using a lawn mower to shred large volumes into small pieces making them easier to contain and spread for mulch. There are many used for leaves in the landscape, even in sophisticated designs. I over used pine straw mulch around many of my shrubs, trees and landscape beds. Rarely does all the mulch decompose.
If you have a vegetable garden spot, add leaves each fall to maintain adequate organic matter into clay soils. This improves aeration and drainage on clay soil and vegetable plant root growth. Organic matter adds small amounts of plant nutrients and can also be used as a mulch to help keep weeds at bay.
Excess leaves can be stockpiled for use next spring in the garden rather than thrown away. Contact James Hodges 864-223-3264 with questions or visit 105 N. University St. at the Old Brewer School on East Cambridge Avenue.
James Hodges is a Clemson Extension agent in Greenwood County. He can be reached at 864-223-3264.