The Garden Muse — Using leaf mulch in your landscape

Published 1:56 pm Friday, September 16, 2022

It is that time of year when some gardeners are prepping their gardens and yards for winter. Mulching protects plants from winter’s fluctuating temperatures, helps keep soil moist, improves fertility, and suppresses weed growth.

Did you know that there is an alternative to the commercial wood mulch that many purchase to protect their garden beds and plants with for the winter season? Well, there is and if you have trees in your yard, it will not cost you any money to utilize. The alternative I am speaking of are the fallen leaves from the trees on your property, which accumulate en masse every autumn on the ground.

The two most important things to do if using leaf litter to mulch is to shred the leaves and apply in the proper thickness. Shredding the leaves allow the air and water to reach the soil underneath more easily. Using dry leaf litter will also help to shred more efficiently and will help the mulch break down quicker once applied. Shredding can easily be done with a mulching mower, shredder, or a leaf blower that will also vacuum (make sure your machine will shred while vacuuming up the leaves.)

The thickness or amount of leaf mulch applied depends on what you are mulching. Trees and shrubs should be mulched at a thickness of no more than 3-4 inches. Perennial Garden beds should receive no more than a layer 2-3 inches thick. I also use it sparingly in my vegetable garden beds to increase the soil’s porosity and add nutrients, 1-2 inches at the most and I am careful to take the time and really shred the leaves good.

Plants can be damaged by locking in too much moisture in the soil with mulch that has been applied too thick, killing plants that are susceptible to root rot and fungal diseases. Most leaves take around two years to decompose. If too much is used adverse effects on the soil and plants may happen due to the excess leaf compost sitting longer than optimal time needed to decompose while depleting nitrogen from the soil and retaining too much water.

Avoid using leaf litter as mulch from Beech, Holly, and Sweet Chestnut trees, they contain higher levels of lignin and lower levels of nitrogen & calcium. Black Walnut and Eucalyptus both contain natural herbicides that will prevent seeds from germinating and may kill existing plants. I personally avoid them all. Oaks have a very tough leaf structure and are tough to break down, I compost the leaf litter for a year or two then use it and have had no problems.

The benefits of natural leaf litter compost are many. The two most satisfying take aways from using it for me have been 1. It is free and 2. It has made me much more aware of the diversity of trees that are all around my property.

Dawn Conrad is a Virginia Cooperative Extension Master Gardener, Herbal enthusiast, Writer and Fiber Artist. She can be contacted at dawn@mygardenmuse.com.