With the arrival of the first rains these days, autumn leaves begin to fall heavily. As day length shortens and temperatures drop, deciduous trees change color before the leaves fall. That's what makes this time of year so special in our gardens.
The science behind leaf color changes is that leaves contain the green color chlorophyll, which is essential for photosynthesis. This makes the leaves appear green. With the arrival of autumn days, the leaves stop producing chlorophyll. Other pigments on each leaf that you cannot see also become visible due to the abundance of chlorophyll. Carotenoids in leaves are responsible for the yellow, orange and brown tones of fall leaves. Anthocyanins give leaves their red and purple hues. Abscission is the dropping of leaves.
Now that you understand a little about the science of leaves, here's what you can do about the abundance of fall leaves in your garden.
Chunks/Mulch: Shredded leaves make an excellent inexpensive mulch for flower beds and shrubs. They not only enrich the soil, but also destroy weeds. Whole leaves become matted after wet weather and, due to the high lignin content, take some time to completely decompose. This can be useful if you are trying to control weeds in an area where they are difficult to control.
FORMS SOIL: Crushed leaves are rich in nitrogen, phosphorus, carbon, calcium, magnesium and sulfur. Mix it into your compost pile or work it directly into the soil.
IMPROVE SOIL STRUCTURE: Crushed leaves are an excellent fertilizer for improving poor or fertile soils. In sandy soils they help retain moisture. In clay soils they help increase drainage capacity. Leaves add humus.
COMPOST: Fallen leaves are especially rich in carbon, making them a good candidate for adding brown leaves to your compost. When compost piles contain too much wet material called greens, composting does not occur effectively. Carbon from the leaves balances the compost mixture.
Keep an eye on the animals: Leaf mulch provides food and habitat for pollinators, salamanders, frogs, bats and spiders. Many species of butterflies and moths overwinter in leaf litter as eggs, pupae, or adults. Especially during the winter months, birds search the foliage for bugs and insects. If possible, it is better to leave the leaves alone.
Terry Kramer is an experienced gardener and journalist. She has written a gardening column for the Times-Standard since 1982. Contact her at terrykramer90@gmail.com.
