Lawn Leaf Management

10 November 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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While we enjoy the beautiful colors associated with fall foliage, we also realize that most of those leaves will soon be on the ground. At this time of year, many people quit managing their lawn and shift their focus instead to leaf management. In some situations, leaf removal by way of blowing, raking, or vacuuming is essential because of lawn use type. For example, golf courses where finding a ball in leaves is next to impossible need to have regular maintenance. However, the treatment and/or disposal of these leaves can be a time consuming and costly process. In some areas, it is actually illegal to place bagged leaves at curbside for pickup due to restrictions on placing lawn waste in landfills.

A leaf mulching mower.

One reasonable alternative for leaf management is a technique that many of you have used for years — leaf mulching directly into the lawn. There are several university research reports detailing how leaf mulching affects lawn health. In almost every instance, the results show that chopping up leaves as part of a regular mowing schedule is an effective means of managing them without harming the lawn. A research report entitled “Leaf Mulching Effects on Turf Performance” from Purdue University turfgrass researchers Zac Reicher and Glenn Hardebeck can be accessed online at http://www.agry.purdue.edu/turf/report/1999/page24.htm. This report does an excellent job detailing the responses of a perennial ryegrass lawn to the application of up to 4000 lbs of maple (Acer sp.) leaves/acre in a single application. Mulching the leaves had no undesirable effects on lawn quality or color, growth, thatch accumulation, soil pH, weed populations, or disease pressure. While the leaves did not prove to be a substitute for proper nitrogen fertilization practices, the overall assessment was that mulching was overall very positive and economical.

There are some important considerations before using leaf mulching on lawns as a method of leaf disposal. While mulching mowers are preferred because of special deck and/or blade designs to mulch clippings, almost any rotary mowing unit can suffice. However, think safety first. Use the rotary mower for leaf mulching, not as a stump grinder or chipper/shredder. Inspect the site and remove sticks and limbs before mulching. This greatly reduces the chance that you or someone else can be hurt, and improves the performance and life of your mower. Wear safety goggles and an air mask over your mouth and nose to protect from debris and dust. Mulch leaves when they are suitably dry rather than soaking wet. While this causes more concerns with dust, dry leaves are much easier to mulch and cause less wear and tear on the mower. Finally, consider the limitations of the mower itself. There is only so much leaf matter that can be handled at one time, so use some common sense regarding how many leaves can be effectively mulched in a single mowing event. Sharpen blades more frequently (to improve the mulching operation and to address the likelihood that your blades will still likely be hitting some debris) and clean filters (air and other) more regularly.

Many pine trees are also shedding a season’s worth of needles during the fall as new growth emerges. Unfortunately, mulching is not an effective way to dispose of pine needles because of their size, shape, and composition. Pine needles are highly resistant to microbial breakdown, and even if they are chopped into smaller pieces, they remain physically intact for months. While resistance to decomposition precludes pine needle disposal by mulching, the durability of pine straw is one reason it is so popular as a landscape bedding mulch.

Consider utilizing your rotary or mulching mower as a leaf disposal tool this fall. Mulching leaves directly back into the lawn has proven to be a cost (and time) effective means of leaf disposal, does not negatively impact lawn health, and helps reduce the volume of landfill waste.

Many counties offer Master Gardener Volunteer training beginning in the New Year. Contact your local Extension Office for more information on classes near you.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Aerating Your Lawn

17 August 2005

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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There are several practices recommended for lawn care at this time of year including pest management, fertilization, and aeration. I suspect you are already thinking about the pest management part due to the large population of Japanese beetles we had this year. I hope you know that August is the best time to treat for these beetles. You will probably see some reminders about fall fertilization of your lawn at your local garden shop. This is the best time for that as well.

a core aerator

One practice that is sometimes overlooked is aeration. Lawn aeration involves the removal of small soil plugs or cores out of the lawn. Although hand aerators are available, most aeration is done mechanically with a machine having hollow tines or spoons mounted on a disk or drum. Known as a core aerator, it extracts 1/2 to 3/4 inch diameter cores of soil and deposits them on your lawn. Aeration holes are typically 1-6 inches deep and 2-6 inches apart. Other types of aerators push solid spikes or tines into the soil without removing a plug (spiking). These are not as effective because they can contribute to compaction. Core aeration is a recommended lawn care practice on compacted, heavily used turf and to control thatch buildup.

As lawns age or sustain heavy use from play, sports activities, pets, vehicle traffic and parking, soil compaction can result. Soil compacting forces are most severe in poorly drained or wet sites. Compaction greatly reduces the pore space within the soil that would normally hold air. Roots require oxygen to grow and absorb nutrients and water. Compaction reduces total pore space and the amount of air within the soil. It has a negative impact on nutrient uptake and water infiltration, in addition to being a physical barrier to root growth. This results in poor top growth and lawn deterioration. Core aeration can benefit your lawn by:

• Increasing the activity of soil microorganisms that decompose thatch.
• Increasing water, nutrient and oxygen movement into the soil.
• Improving rooting.
• Enhancing infiltration of rainfall or irrigation.
• Helping prevent fertilizer and pesticide run-off from overly compacted areas.

If in doubt about aeration, remove a square foot section of lawn at least 6 inches deep. If grass roots extend only into the first 1-2 inches, your soil may be compacted and could benefit from core aeration. Expect a seasonal effect with cool-season grass roots being shortest in late summer and at their greatest depth in late spring.

Other reasons to aerate include:

• Your lawn is heavily used or driven upon on a regular basis, causing the turf to thin.
• The thatch layer is in excess of 1/2 inch.
• You have a heavy clay soil.

A lawn that is not exposed to soil compacting events will likely grow well and may not need aerification. Winter freezing and thawing cycles and earthworm activity can help loosen slightly compacted soils. If the lawn has a thatch layer in excess of 1/2 inch, then core cultivation can be used as a preventative approach to control excess thatch build up. Newly seeded or sodded lawns should not be aerated in the first year.

In Virginia, the best time to aerate cool season lawns of tall fescue and Kentucky bluegrass is in late August to mid September. This is when these lawns are coming out of summer dormancy and beginning a period of vigorous growth. Lawns will recover quickly from aeration at this time. Competition from weeds is also minimal during this time. Warm season lawns like Bermudagrass and zoysiagrass are best aerated during June and July, as this is their period of rapid growth.

Aerators may be rented at many garden or rental centers. Some lawn or landscape companies will perform the service for a fee. Be sure that the machine has hollow tines or spoons to bring the soil core to the surface. Look for machines with deeper tines and weight over the tines for better penetration into the soil. Busy rental times include most spring and fall weekends; reserve early or plan on weekday use. These machines are large and heavy; they will require special handling and larger vehicles for transport. Many people cooperate with neighbors and make it a group effort, thereby also lowering the overall cost. If renting, be sure you are instructed in and comfortable with the operation of the machine before bringing it home.

When you are ready to aerate keep the following guidelines in mind.

• The soil should be moist but not wet.
• Lawns should be thoroughly watered two days prior to aerating, so tines can penetrate deeper into the soil and soil cores easily fall out of the tines.
• If aerating after prolonged rainfall it is important to wait until the soil has dried somewhat so soil cores do not stick in the hollow tines.
• Thorough watering means 1 inch of water from irrigation or rainfall. An inch of water can be measured by marking the side of a pet food can placed in the lawn.
• Applying 1 inch of water may be difficult to achieve in a single watering, given the slow infiltration rate on most Virginia soils. Therefore, smaller amounts of water applied every 3 to 4 days may be required to allow water to enter the soil without causing runoff.
• Aerate the lawn in at least two different directions to insure good coverage. Be careful on slopes, especially steep ones, as well as near buildings and landscape beds.
• It is extremely difficult to core aerate heavy clay soils or soils that have stones, rocks or tree roots below the soil surface.
• Be sure to mark sprinkler heads, shallow lines from sprinkler, underground utilities, cable, and septic lines before aerating so they will not be damaged.
• Soil cores are best left on the lawn surface; they typically work back into the grass in 2-4 weeks.
• Lawns may be fertilized and seeded immediately following aeration with or without further soil top dressing.
• If your soil is heavily compacted, you can apply stable, mature compost 1/4 inch deep. Rake the compost over the lawn, filling the aeration holes.
• Lawns can be aerated once a year, especially under heavy use conditions.

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Contact your local Virginia Cooperative Extension office and speak with an Extension Agent or Master Gardener volunteer for more advice and information on lawn and landscape topics. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.