Using and Disposing of Fall Leaves

Fallen leaves are valuable asset to landscape

Bill Sevier: Ask a Master Gardener

Saturday, December 19, 2015

Q: What is the best thing to do with leaves if you don’t want to place them in the trash? E.L., Tulsa

A: There are many options for your leaves other than the trash. Placing them at the curbside should be your last choice. Leaves are valuable assets in the landscape; they have significant amounts of nutrients and organic material that are so valuable. Some studies have shown leaves to be composed of up to 1 percent nitrogen, the No. 1 nutrient needed by all plants. This is about as much nitrogen as found in composted cow manures, which are used for an organic source of fertilizer.

Leaves may be mowed into any healthy lawn. Done properly, the leaf particles drop down below the turfgrass canopy. This adds nutrients and organic material to the soil and has no adverse effects on the turfgrass. One study mowed 1 pound of leaves per square yard of lawn (equal to about a 6-inch depth of leaves) for five consecutive years and found no undesirable effects on soil chemistry, amount of thatch or grass diseases.

Adding shredded leaves directly to your garden beds as mulch is another good use for them. They are best if shredded first with a lawnmower. Shredding them reduces their volume at least 10 fold, which produces an excellent mulch. They will decay over the following year, releasing nutrients and organics. Your beds will then be ready for another load of leaf mulch next fall.

One concern that is often raised about the use of leaves in the garden is that the leaves, especially oak leaves, will acidify the soil to excess (or add needed acid to azalea beds). There have been studies done looking at the effect on soil chemistry when a variety of leaf types were used either as mulch or tilled into the soil. As they decay, they had no effect on garden soil acidity, even when used in fairly large volumes. The one exception to this was pine needles, which added acid to the top inch or so of the soil after decay.

Tilled into the soil, shredded leaves are an excellent amendment. They are best added in the fall or early winter. This will give them a chance to begin the breakdown process before spring. Organics that are tilled into soils will loosen clay soils and help sandy soil retain water and nutrients.

Lastly, add the shredded leaves to the compost pile. Because leaves are mostly carbon material, add a little fertilizer for a nitrogen source to aid in the composting process. If you do not have a compost bin, heap them into a pile in an out-of-the-way area, and they will compost.

Any of the options above are much better for you and the environment than adding leaves to the trash.

Garden tips

• All birds need and appreciate clean feeders and unfrozen water on cold days. Place feeders close to protective shelter, if possible.

• Light prunings of evergreens can be used for holiday decorations. Be careful with sap that can mar surfaces.

• With the warmer weather, newly seeded fescue will continue to grow roots and make energy if you keep them free of leaves.

• Continue to control broadleaf weeds in well-established warm- or cool-season lawns with a post-emergent broadleaf weed killer.