Fall Lawn Maintenance is special to the Mirror By Jane McKinley, ESVG Master Gardener
Everyone loves a lush, green lawn that is easy on the bare feet and provides an attractive vista that frames the home. To this end, most homeowners in Virginia think of fall as the time to perform annual maintenance on their lawns. Depending on the variety of grass, this is partially true; however, a regular maintenance plan of watering and mowing is necessary throughout the year to ensure a healthy lawn. Fertilization, weed control and leaf management are more specific to the varieties of grass in the lawn or the time of year. There may also be an occasional need for dethatching, pH adjustment, aeration and disease and insect control.
During hot, dry weather, lawns can use an inch or more of water per week. The lawn should be watered deeply when the soil begins to dry out but before the grass actually wilts. A light sprinkling on the surface of the grass is more harmful since this encourages roots to stay close to the surface of the soil, dependent on more watering maintenance, and increases crabgrass germination. If it’s not possible to maintain a regular watering regimen, it is best to allow the grass to go dormant until natural conditions bring it back. The best time to water is early morning when evaporation is minimized and water-use efficiency is maximized. Early evening or night watering is not recommended because it leaves the blades and thatch wet at night, introducing the potential for disease.
|This article is an excerpt from the Eastern Shore of Virginia Master Gardener Fall newsletter, “Gardening on the Shore.” It is an example of the types of knowledge that one will acquire and share with the community as a Master Gardener. If interested, fall intern classes begin on October 3, 2018 and continue through February, 2019 with a break in November & December. For more information, go to the ESVMG website or call 757-678-7946 EXT. 29. Applications will also be available at the Cape Charles Farmers Market on Sept. 11.|
Mowing is the most frequently necessary maintenance practice in the production of a good lawn. See the excerpt from the Virginia Master Gardener Handbook for guidance on recommended mowing practices.
It is important to identify the type of turfgrass in your lawn since the maintenance schedule other than mowing and watering is unique for each. Turfgrass varieties fall into two basic categories: cool-season and warm-season. Cool-season grasses, such as Kentucky bluegrass, tall fescue, fine leaf fescue and perennial ryegrass, have a long growing season and provide green winter color. Kentucky bluegrasses are best suited to areas in the western part of the state, so these should be avoided in our area unless included as a small percentage of a mix. The tall fescues dominate the home lawn market and are oftentimes mixed with a small percentage of Kentucky bluegrass to help recovery in high traffic areas. Fine leaf fescues exhibit the best shade and drought tolerance and can grow well in low-nitrogen and higher acidic soil. They require the least intensive maintenance of any of the grasses adapted to Virginia.
Warm-season grasses, such as zoysiagrass, Bermudagrass, centipedegrass and St. Augustinegrass, go dormant after the first hard frost and stay brown through the winter months. The wider leaf varieties of zoysiagrass tend to have the best cold tolerance of the warm-season grasses in Virginia. Zoysiagrass also has a low requirement for fertilization and irrigation, does well in full sun and some shade, has very few insect and disease problems and has a density which helps to keep down undesirable weeds. Bermudagrass has exceptional drought tolerance, an aggressive growth habit and grows extremely well on the Eastern Shore. While the winter color of the warm-season grasses may make them less desirable, maintenance costs are somewhat reduced since the shorter growing season requires less water and fewer mowings per year.
For both types of turfgrasses, it’s important to test your soil at least once every three years to determine if supplemental nutrients other than nitrogen are required. Soil test results, done at least one month before lawn renovation begins, determine the basic nutrients available in the soil and will give recommendations for amendments such as lime and fertilizer. The numbers on the fertilizer bag, such as 10-10-10, indicate the percent of nitrogen (N), phosphate (P2O5) and potash (K2O). Nitrogen requirements of turfgrass cannot be reliably evaluated by a soil test, therefore, the test results will contain a nitrogen recommendation for the kind of grass being grown (refer to “Lawn Fertilization in Virginia,” for more information.) Since too much phosphorus in the environment causes nutrient pollution that results in serious environmental and human health issues, apply it only when indicated as necessary by a soil test. Likewise, although maintaining sufficient levels of potassium (potash) in plants is very effective in improving winter and summer hardiness of turfgrasses, if a soil test indicates that potassium levels are adequate, the supplemental application wastes money and negatively affects its balance in the soil with other nutrients.
Maintenance for Cool-Season Turfgrass
Late summer to mid-fall is the best time to establish and refurbish cool-season turfgrass. This time of year presents growing conditions conducive for improving lawn density through the development of new shoots and stems, increased carbohydrate storage (i.e., food for the plant) and enhanced root production.
A diagnosis of your soil’s fertility and pH status is the best way to identify why your grass may have had problems during the past growing season and to prepare the soil to maximize success for the next growing season. Since growing conditions are ideal at this time of year, grasses respond quickly to soil-test-recommended applications of fertilizer and lime. And, if recommended, the fall and winter months are ideal times to make lime applications since it takes weeks to months to fully realize the benefit of the treatment.
Supplemental seeding of an established lawn in late summer or fall can be beneficial. To minimize the need for weed control, promote the rapid establishment of new grass by applying a generous amount of seed and keeping it well watered. If you seed in late summer, a mid-fall application of a pre-emergence herbicide to control undesirable weeds such as annual bluegrass, henbit, chickweed and geranium will help reduce them by inhibiting their seed germination. If you are planning a fall planting, remember that these chemicals will also prevent cool-season turfgrass seed germination. Carefully read the herbicide label to ensure that the product is safe and determine when the product can be applied relative to seeding. Seedlings are much more sensitive to chemical applications than mature plants.
There are also numerous post-emergence broadleaf herbicides available for fall weed control. Many cool-season perennial broadleaf weeds (plantains, dandelion, clovers) will also have a surge of vegetative growth like the turfgrass, and this presents a great opportunity to maximize the effectiveness of chemical control. Controlling these weeds will improve overall turf density in the fall and will result in even lower weed populations the following spring because of the thick turfgrass canopy. Refer to “Fall Lawn Care” for more information on herbicide types and recommendations.
There is potential for early fall applications of certain insecticides for grub control, but the ideal period for their control is between July and August.
Chemical sprays over the top of leaves are often a waste of time, effort, and money in terms of receiving the anticipated response in pest control. Granular applications will have a better chance of delivering the chemical to the soil, but not all chemicals are available in granular formulations. One thing that can be done with the leaves before any chemical application is to simply mulch them back into the lawn.
You can make supplemental nitrogen applications later in the fall if you want a boost in growth or color. The fertilization program following the acronym “SON” (representing the months of September, October, and November) is ideal for maximizing the benefits of nitrogen fertilization on cool-season grasses.
Core aeration (removing plugs from the soil) is a standard method for reducing compaction by improving the circulation of air and water in the soil. Dethatching physically removes thatch, a layer of un-decomposed stems and other living and decaying organic matter that develops between the soil and the turf canopy. Both methods are best done in the fall for cool-season turf when recovery can be optimized by weather conditions and a fertilization and irrigation program.
Maintenance for Warm-Season Turfgrass
The cooling temperatures of fall provide warm-season grasses the opportunity to increase carbohydrate reserves and root production as leaves continue to photosynthesize but overall shoot and leaf development rates decline. The last application of nitrogen for lawns with bermudagrass or St. Augustinegrass should be made no later than one month prior to the anticipated frost date. Grasses with minimal nitrogen requirements, such as zoysiagrass and centipedegrass, should only be fertilized during the most active growing months. As mentioned earlier, only apply phosphorus when needed according to soil tests for established lawns. A key to success is ensuring that other nutrients, particularly the winterizing nutrient potassium, are present in satisfactory quantities. The benefits of potassium in warm-season turfgrass winter survival are often more pronounced than those of cool-season turfgrasses, so be sure to periodically conduct soil tests to evaluate where these levels are prior to winter’s arrival.
The dormant warm-season grass provides little to no competition to cool-season weeds, thus weed control is often necessary. Most turf pre-emergence herbicides labeled for use in warm-season turf can control annual bluegrass, and timing is crucial to get the best control. In most parts of the state, germination begins in early September. Many of these chemicals also have excellent activity on many broadleaf weeds.
Insect and disease pressure for a grass preparing for dormancy are minimal. If a bermudagrass turf has a history of spring dead spot, consider a preventive application of a labeled fungicide in early to mid-fall before the turf goes dormant. This is the only time to chemically control this disease because spring treatments are not effective.
Fall is too late in the growing season to safely aerate or vertically mow warm-season turfgrasses. Do this in late spring or early summer when these grasses are actively growing.
Resources for More Information:
“Fall Lawn Care,” Virginia Cooperative Extension, Publication 43-520
“Soil Sampling for the Home Gardener,” Virginia Cooperative Extension publication 452-129
“Lawn Fertilization in Virginia,” Virginia Cooperative Extension publication 430-011
“Maintenance Calendar for Warm-Season Lawns in Virginia,” Virginia Cooperative Extension publication 430-522
“Maintenance Calendar for Cool-Season Lawns in Virginia,” Virginia Cooperative Extension publication 430-522