Put fall leaves to work

by Donna Tatting

Chisago County 

Master Gardener

Fall is my favorite season.  All my yard and garden chores are done without the heat and humidity that zap my energy, and all around me are trees transitioning from green to their bold fall colors.  And along with all the trees on my property come the mountains of leaves.  Lucky for me, I live on property that allows me to dispose of my leaves on site, but some of them are put to valuable use in my gardens.

One of the very best sources of organic matter is leaves.  Leaves are packed with trace minerals that trees draw up from deep in the soil. When added to your garden, leaves feed earthworms and beneficial microbes. They lighten heavy soils and help sandy soils retain moisture, and they make attractive mulch in the flower garden. They’re a fabulous source of carbon to balance the nitrogen in your compost pile, and they insulate tender plants from cold.

To make the best use of leaves, they should be shredded. I let the leaves pile up on the lawn and then drive over them a few times with the lawn mower. Shredding one leaf into five or ten smaller pieces does several good things. It increases the surface area, giving microbes many more places to work. It prevents the leaves from packing together into layers that won’t let water or air penetrate, and it reduces the volume dramatically; ten bags of whole leaves becomes just one bag of shredded leaves.

In time, shredded leaves become something called leaf mold, which makes fabulous mulch. What’s more, it does wonders for the soil. A few days ago, I moved a wooden set of steps that had been removed from a front porch.  We had placed it out next to the barn, intent on finding some use for them.  Well, that was about 10 years ago.  When we moved the steps, I discovered that oak leaves had been collecting underneath all these years and had become this rich dark pile of compost — a perfect example of leaf mold.

If you have a compost pile or compost bin, leaves are one of your most valuable ingredients.  Add leaves to the working compost pile throughout the year to balance the food scraps and other materials that are usually high nitrogen. The leaves also keep the pile from getting compacted and soggy.  If you don’t compost, you can just work the shredded leaves right into the garden soil.

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