California Department of Resources Recycling and Recovery (CalRecycle) 

Keeping Green Landscapers Guide

Managing a Waste-Efficient Landscape

Every landscape requires some degree of maintenance that will produce trimmings, no matter how carefully it was designed or installed to prevent waste. These trimmings can be managed in many ways, including composting. However, from an efficiency perspective the best way to manage landscape trimmings is to simply leave them in place! Nowhere is this practice easier than on those green areas that make up a huge part of California’s landscapes—lawns.

Lawns/Turf

Yard trimmings make up the largest single component of California’s municipal waste. It is estimated that grass clippings make up about half of all yard trimmings over the course of the year, and much more in areas with expansive suburban lawns.

University studies have shown that the average California lawn generates 300 to 400 pounds of grass clippings per 1000 square feet annually. This can be as much as eight tons per acre each year! Significant quantities of water, fertilizer, and labor go into producing all those clippings. By practicing responsible turf management, including "grasscycling," a landscaper can both reduce those inputs and eliminate the waste.

What Is Responsible Turf Management?
Responsible turf management refers to installing and maintaining a lawn in an environmentally sound and cost-effective manner. By doing it right from the start, turf can be managed with only moderate water and fertilizer requirements, and the headaches of thatch removal and disease control can also be minimized.

Installation.
By preparing the area correctly before laying turf or seeding, long term management can be eased significantly. Make sure that the area has good drainage, achieved through proper grading and underground conduits. Avoid installing turf on berms or severe slopes unless necessary. Other drought resistant ground covers might serve the purpose better than turf. Whether native soils are sandy or clay, the turf will benefit from the addition and deep tilling of well composted organic material. This helps the soil and grass plants better manage water and nutrients. Allowing for deep root growth will contribute to overall turf health and resilience.

Watering.
Turfgrasses vary in their need for water. Most grasses in California need about one inch of water every five to seven days in the growing season and much less during slow growth months. Lawns watered too frequently tend to develop shallow root systems, which may make them more susceptible to stress and disease. Deep, infrequent watering produces a deeper, extensive root system which enables turf to resist disease and stress. Overwatering not only is wasteful, it also causes lawns to grow faster and require more mowing.

It is a good idea to regularly check irrigation systems for even coverage. A simple audit can be performed by placing empty containers in a number of locations around a lawn, and then run the system. (Empty tuna cans work great, and are just about two inches deep.) See if the containers fill evenly, and how much water is delivered during a regular watering. Adjust sprinkler heads to avoid dry or soggy spots.

The best time to water is early morning, as less water is lost due to evaporation, and water pressure is at its peak. Try to avoid watering in the evening because prolonged damp conditions may encourage disease development.

Fertilizing.
Proper fertilization is essential in maintaining a healthy lawn. However, over-fertilization can weaken a lawn by causing excessive and succulent top growth. For moderate, even growth, use a combination of fast acting fertilizers (ammonium nitrate, ammonium sulfate, or urea) and slow release nitrogen sources such as sulfur-coated urea, urea formaldehyde, IBDU or organic fertilizers. Avoid using large quantities of fast acting fertilizers. These fertilizers produce very fast growth for short periods.

Check with a local turf specialist to determine the fertilization rates for your grass type. Chances are you can get by with less than the recommended amount of fertilizer and still have a beautiful lawn.

Regardless of the grass type and its fertility needs, as a general rule, it is better for the lawn, and grasscycling, to apply smaller quantities of fertilizer more frequently rather than larger amounts less frequently.

What Is Grasscycling?
Grasscycling is the natural practice of leaving clippings on the lawn when mowing. It is obvious how this practice can save resources like landfill space, but there are additional benefits as well. The clippings quickly decompose, returning nutrients to the soil. Grasscycling, in conjunction with the practice of reducing water and fertilizer inputs, can reduce mowing time in addition to disposal costs.

Many people treat their lawns like a "crop"--they (over) water and (over) fertilize their lawns to encourage excessive growth. The harvested "crop" (those grass clippings) is then bagged and transported to a landfill. What a waste! Proper mowing, watering, and fertilizing practices result in more moderate turf growth yet still produce a healthy, green lawn. Grasscycling can be practiced on any healthy lawn as long as responsible turf management guidelines are followed.

The nitrogen contained in grass clippings removed from a lawn almost equals the recommended application rate for healthy turf (about 5 pounds of nitrogen per year per 1000 square feet). While some of this nitrogen is lost through the decomposition of the clippings, leaving the clippings on the lawn by grasscycling can have the overall impact of reducing fertilization requirements by 15 to 25 percent or more. Similar savings on water use are possible.

A cooperative effort between the CIWMB (now known as the Department of Resources Recycling and Recovery, or CalRecycle), the Department of General Services, the Office of Buildings and Grounds, and the Toro Company resulted in a demonstration program within the Capitol's grounds. The fountain circle on the west side of the Capitol was part of the demonstration.

Mowing.
Proper mowing is required for successful grasscycling. It is best to cut grass when the surface is dry (no drops of moisture on the grass), and keep mower blades sharp. Follow the "1/3 rule": mow the lawn often enough so that no more than 1/3 of the length of the grass blade is removed in any one mowing.

Mowing Guide For Common California Turfgrass
Grass Type Mower Setting
(inches)
Mow When Grass
Reaches This Height (inches)
Bentgrass 1/2 - 1 3/4 - 1 1/2
Bermudagrass (common) 1 1 1/2 1 1/2 - 2 1/4
Kentucky Bluegrass 1 1/2 - 2 1/2 2 1/4 - 3 3/4
Kikuyugrass 1 - 1 1/2 1 1/2 - 2 1/4
Perennial Ryegrass 1 1/2 - 2 1/2 2 1/4 - 3 3/4
Tall Fescue 1 1/2 -3 2 1/4 - 4 1/2
St. Augustine 1 - 2 1 1/2 - 3
Zoysia 1/2 - 1 1/2 3/4 - 2 1/4

Proper mowing will produce short clippings that will not cover up the grass surface. You may have to cut the lawn more frequently, or double cut, when the lawn is growing fast, such as in the spring, but much less when the turf is growing slowly. Additionally, in many areas of California, raising the mowing height in the summer encourages deeper roots and protects grass from drought and heat damage.

You can grasscycle with most any mower. The mower collection bag can be removed to allow clippings to drop on the lawn. However, if your mower does not have a safety flap covering the opening where the bag fits into the chute, or a plug for the chute, contact your local retailer to purchase a retrofit kit. A bit of experimentation might be needed to keep clippings from clumping when using a conventional mower. In addition, do not to compromise your mower’s safety systems.

Additionally, most lawnmower manufacturers have developed mulching or recycling mowers which cut grass blades into small pieces and force them into the turf. Mulching or recycling mowers make grasscycling easy. Studies have shown that seasonal mowing time can be reduced by 50 percent or more since the bagging and disposal of clippings is eliminated. Cost savings can even be realized in hidden ways. By not handling heavy bags of clippings, back injuries and other physical maladies can be avoided.

Clearly there are times when collecting the clippings is necessary, such as when there are excessive leaves on the turf, or when the grass is too wet. This guide will discuss options for managing those clippings by composting later. In the meantime, note that several brands of recycling mowers are available in California to help landscapers grasscycle. If you are thinking of replacing some of your mowers soon, seriously consider purchasing mowers with grasscycling capabilities.

The state has worked closely with the University of California Cooperative Extension in the development of informational materials to educate the public as well as the landscaping industry about grasscycling. Close cooperation with the California Landscape Contractors Association (who officially endorse grasscycling), the Northern California Turf and Landscape Council, and the Southern California Turfgrass Council has resulted in widespread interest and increasing conversion to this time, money, and landfill-saving practice.

Common Questions About Grasscycling

Does grasscycling cause thatch build-up?
NO!
Research has shown that grass roots are the primary cause of thatch, not grass clippings. Thatch is composed mainly of roots, stems, rhizomes, crowns, and stolons. These plant materials contain large amounts of lignin (wood) and decompose slowly. Grass clippings are approximately 80-85 percent water with only small amounts of lignin, and decompose rapidly. Some grasses such as bermudagrass and kikuyugrass are more thatch-prone than others.

A small amount of thatch (approximately 1/2 inch) is actually beneficial to a lawn, providing insulation to roots and serving as a mulch to prevent excessive water evaporation and soil compaction. Thatch may also create a cushioning effect for lawn play.

Does grasscycling spread lawn disease?
NO!
Improper watering and fertilizing are the primary cause of disease spread. If an accommodating environment for turfgrass disease is present, infestation will occur whether or not clippings are collected.

Will grasscycling make my lawn look bad?
NO!
If a lawn is properly mowed, watered, and fertilized, grasscycling can actually produce a healthier-looking lawn. It is important to cut the lawn frequently to produce small clippings that will fall between the standing blades and decompose quickly. However, if a lawn is not cut frequently enough and long clippings are left on the lawn, it may produce a "hay-like" look which can be unsightly.

Many golf courses and parks have practiced grasscycling for years. Ninety-eight percent of the residential participants in a grasscycling study conducted by Texas A&M reported that they will never bag their clippings again!

Just remember, grasscycling:

  • Saves time (no more bagging).
  • Saves money (less water and fertilizer are needed, no landfill fees).
  • Encourages a healthier lawn (clippings contain valuable nutrients).
  • Saves energy (mowing time, hauling to the landfill).
  • Saves valuable landfill space.

Are there alternatives to grasscycling?
YES!
Grasscycling is not feasible in every situation. Prolonged wet weather, mechanical breakdown of mowers, or infrequent mowing are situations where grass clippings should probably be bagged since an excessive volume of clippings may be generated. But do not throw the clippings away!

Grass clippings are an excellent addition to a backyard compost pile. Clippings can also be used as mulch to provide weed control and prevent moisture loss around flower beds, trees, and shrubs. Mulching with clippings should be avoided, however, if they are of an invasive variety, such as bermudagrass, or if herbicides have been applied recently to the lawn. See the Grasscycling section of this guide for more information.

Trees/Shrubs/Flowers

While managing grass clippings can be as simple as leaving them where they fall, clearly there are trimmings and other debris that come from trees, shrubs, and flowers that require a bit more attention. However, the concepts discussed in the preceding section on grasscycling—proper establishment, water, fertilization, and trimming—hold true for the waste efficient care of large plants. Basically, the more natural and moderate a plant’s growth, the less waste producing maintenance will be required in the long run. Additionally, the trimmings that are produced can be used on the spot, as a mulch, to encourage the desired plant health and growth patterns.

The easiest way to manage trees is by natural neglect—that is, let a tree develop and grow in its most natural manner possible rather than fighting it with loppers. Hopefully, the trees of a landscape were selected and planted with consideration to location (e.g. not under powerlines, or too close to each other or structures) so that they could mature without excessive trimming. Of course, early life shaping of a tree is important to ensure a safe structure, but once established all that is usually necessary is vigilance—watching for any injury or disease, or unsafe branch development.

Branches that must be removed can be chipped or shredded and used as mulch around the tree. Since most trees do best with minimal disturbance within their drip line, the designation of this area as a natural mulch repository can be very beneficial. The leaves of deciduous trees, as well as the ongoing drop of evergreens, can also be used as mulch within this zone. Through the work of beneficial bacteria, fungus, and earthworms, most organic mulches will be "consumed" over the course of a few seasons, slowly feeding the trees while conserving moisture, suppressing weeds, and moderating ground temperature.

Shrubbery can be treated in much the same natural way as trees. Careful selection and placement of larger woody perennials will result in minimal maintenance and waste generation. Often, though, shrubs must be pruned to encourage bloom production or to achieve a desired shape. Care should be given to the timing of such pruning since many shrubs set flowers on second year growth. Also, new growth in the spring provides a shrub with a fresh set of energy-producing leaves. Continued removal of this growth by excessive pruning can lead to plant stress and ill health. If unsure of the best pruning time for a particular plant, consult your nursery expert or a University of California Cooperative Extension horticultural advisor.

The trimmings from most shrubbery can also be chipped or shredded and used as a mulch underneath the plants. Not only does this help conserve moisture and suppress weeds, but it can be an attractive alternative to other decorative mulches commonly used, and it can be far less expensive to produce your own mulch rather than buy.

Try to avoid using diseased or seed bearing material directly as a mulch under trees or shrubs. This material can be processed by first composting (see Composting section in this guide) in a hot pile to kill pathogens and seeds before use as a mulch.

Perennial flowering plants may or may not produce much waste, depending on whether the plant dies back in the winter, or simply goes semi-dormant before blooming the following year. Most "color" perennials require some maintenance to keep their shape, control unsightly spread, or to clean up dead portions. These materials can be added to a compost operation for processing into an amendment or mulch.

Aesthetic life extended by "dead-heading," or picking off spent flowers to encourage continuing bloom. When annuals must be pulled due to client demand, consider a donation to a community garden so that the plants can be put to continued good use, and kept out of the landfill. Annuals that have expired can also be composted. For a long term, lower-waste option, consider replacing some annual color with a mixture of perennials that will bloom in succession throughout the year.

As noted in the previous section on landscape establishment, healthy soil, appropriate plant selection, proper design and placement, and controlled irrigation will go a long way toward producing a healthy, attractive landscape that requires minimal waste producing maintenance. The subsequent use of the leaves and trimmings that are produced, as a mulch or compost, will contribute to the landscape’s health, and your time and money savings.

Checklist

Use this list to help you do your part by reusing clippings and trimmings by grasscycling and mulching. It’s good for your lawn, your plants, and your community.

  • Turf areas have been installed properly, with adequate soil preparation and appropriate grass variety.
  • Turf is being deep watered evenly at a rate appropriate for the grass variety, climate, and time of year.
  • Turf is being fertilized moderately with slow release fertilizers only as needed.
  • Turf is being mowed at a height and frequency that allows for grasscycling, the natural recycling of clippings by leaving them on the lawn.
  • Any clippings that must be collected are being used as mulch, composted or delivered to an organic material recycler.
  • Trees and shrubs are allowed to grow in natural shapes with minimal pruning.
  • Trimmings from trees and shrubs are chipped and used as mulch, composted, or delivered to an organic material recycler.
  • Annual and perennial color is managed to extend bloom, maintain plant shape, and minimize waste.
  • Weeds are controlled with mulch layer, fabric, cultivation, or water management to prevent nutrient loss and waste generation.

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Last updated: April 14, 2011
Organic Materials Management http://www.calrecycle.ca.gov/Organics/
Contacts: http://www.calrecycle.ca.gov/Organics/Contacts.htm