What to Do With Home Yard Waste - PUB2971

With warm weather and sunshine comes the sounds of birds singing, kids playing and lawn mowers running. Maintaining your yard and preserving the natural landscape can create a lot of waste that needs to be managed. Yard waste can represent up to 20% of the solid waste stream going to Missouri's landfills. Missouri's solid waste management law focuses on the need to reduce the volume of waste generated and sent to our landfills. Fortunately, yard waste is one part of the waste stream that can be managed in our own backyards, using techniques such as mulching and composting.

Mulching

Mulch is any organic material such as wood chips, grass clippings, leaves or compost spread over the surface of the soil. Mulch conserves water, keeps down weeds and keeps soil temperatures from becoming too hot or too cold. Mulch also protects sloping ground from soil erosion and stops compaction caused by driving rain or foot traffic. In addition, mulch provides ideal conditions for earthworms and other soil organisms which are necessary for healthy soil and plants. When mulches break down, they become humus that feeds the soil. A good mulch will do all this and be readily available, free, easy to apply and will stay in place without much effort. 

The best place to look for mulch materials is in your own yard. Every yard has grass, leaves and other green materials that can be made into mulch. If you can use wood chips, try contacting a tree service or landscaper listed online. If they are working in your area, they are often happy to deliver woody wastes and avoid extra travel and dumping expenses. Some wood shops and coffee roasters make their organic byproducts available to customers and the general public.

Don't Bag Grass Clippings

The easiest way to start mulching is to take the grass catcher off the lawn mower. Your mower service agent should be able to put a trapdoor over the discharge vent if your mower does not already have one. For conventional side discharge mowers without a trapdoor, mulching may require a bit of raking following mowing to break up the little rows of clippings. To avoid raking the entire lawn, mow from the outer edge in ever smaller circles toward the center, making sure that the side discharge mower is "walking" or blowing the grass clippings ever closer to the central point. In this manner, clippings are chopped several times and most fall between the blades as mulch. The few left near the center can easily be raked and placed into the compost bin or spread in.

Cutting grass higher and with only one-third the blade height is easier and faster than cutting grass that has become overgrown. Fertilizing can be decreased since grass clippings contain 4% nitrogen and act like a time-release fertilizer when they are returned regularly to the soil. Grass clippings return to the soil to form organic humus that helps hold water while keeping the soil loose and aerated.

When asked in a recent survey in Texas, many householders stated the main reason they bag their grass is to avoid generating thatch. While thatch is a problem in many lawns, turfgrass specialists have numerous studies that show  grass clippings do not cause thatch to build up. Thatch is caused by high-lignin stubble at the plant base derived from roots, rhizomes, crowns and stolons that decompose slowly. The green clippings contain little if any, lignin and decompose quickly. If anything, mulching green grass clippings can actually help decompose thatch by supporting a healthy soil ecosystem. With grass mulching, some lawns may need additional aeration and watering to help soil organisms decompose the clippings properly, especially during dry periods.

Tools for Mulch-Making

A rotary mower run across dry leaves will make a fine-textured mulch for annuals and smaller plants. Mulching mowers have become quite popular in recent years and their new features are proudly displayed by dealers. Advertising campaigns are helping convert homeowners over to these new "zero discharge" mowers. Mulching mowers are designed differently from conventional mowers with closed trap doors. The first difference is, of course, the lack of a discharge point and a catcher. The second is the horsepower rating, since mulching mowers require more horsepower to cut and re-cut the grass. The special blade not only cuts, it also acts as a vacuum and fan that circulates the clippings back to the blade for additional pulverizing. The air pressure then forces the chopped clippings downward into the lawn.

Mulching mowers require a lawn not overly wet and has not been left too long between cuttings. The height of the grass should be somewhat higher than the height of the blade. For the average lawn, if the grass is left at 2-inches following mowing, the grass would be cut when it reaches three inches. While the new system takes some getting used to, user satisfaction is running near 100% for those who have made the switch. The lawn must be mowed more often than with conventional mowers, but the time actually spent in the yard is less because there is no need to continually stop and empty the catcher. Mulching mowers should be used every five to six days instead of every week.

A small electric chipper will make a fine-textured mulch of woody stalks and branches up to 1-1/4 inches thick. Gas-powered shredders of 5 to 8 horsepower capable of processing materials up to 3 inches in diameter can be rented or purchased. Large gas-powered chippers able to handle woody-wastes up to 6 inches in diameter are available at rental shops. In general, the larger the machine, the faster the mulch-making.

Where to find mulch-making tools? Look under "Rental Service Stores" and "Yards" online and find tool rental locations nearest you. Call ahead, because not all tool rental stores carry chippers and shredders. Let them know the type of material you want to turn into mulch and find out if their machine can do the job. Shredders and chippers are also sold at lawn and garden equipment stores listed online.

Applying Mulch

Some general rules for mulching: Annuals and perennials (both flowers and vegetables) should be mulched with materials, such as grass clippings and leaves, that break down in a relatively short time. This allows you to turn under the mulch on annual beds when the soil is dug. Grass clippings can be spread regularly in thin layers over vegetable and flower beds, or mixed with leaves and spread in a thicker layer. Spread grass clippings no more than 1 inch thick so they don't mat and prevent water from penetrating into the soil. Leaves of deciduous trees can be spread as mulch in the fall. Evergreen leaves can also be used, but they take longer to turn a dark color and decay. Sawdust and other finely-ground woody materials can be used on the surface, but should not be mixed into the soil. These finely ground materials that have not been composted may tie up nitrogen in your soil, causing your plantings to become yellow and stunted.

Trees and shrubs should be mulched with an attractive thick layer of wood chips that requires little maintenance. Paths can also be covered with wood chips in layers as thick as is practical to wear longer and keep down weeds. Some experts recommend placing a layer of plastic or cardboard underneath the mulch.

Applying mulch materials: Weed the area to be mulched before applying the mulch. For best results, mulch can be spread around any plant as far as the distance of its outermost branching (this is called the drip line ), or it can cover an entire garden bed. Mulch can be spread thickly if water is able to penetrate and if it does not smother the roots of the plant being mulched. Three inches of mulch is safe for any woody plant and up to eight inches of mulch can be used for large trees. Thick mulches are harmful to shallow-rooted plants such as rhododendrons and azaleas.

Composting

Compost is a natural fertilizer made of food scraps and yard waste, which can be added to soil to help retain moisture, feed plants, improve the soil around trees and shrubs and top dress lawns. Compost stimulates plant growth through time release nutrients. It also protects the landscape against weather extremes, especially drought, by keeping soils warmer in winter and cooler in summer. By using food scraps and yard waste to make compost, we keep those materials out of our landfills, where they take up valuable space and release methane, a greenhouse gas. For more information about composting at home, see Homeowners’ Composting Guide - PUB0183.