Let There Be Lawn

Drive through Knoxville, TN neighborhoods on nearly any weekend after Valentine’s Day and you’ll often see one thing — people beginning the process of cleaning up their yard for spring. In addition to picking up debris from trees and preparing beds, attention is often paid to the lawn. A common refrain heard each spring is people vowing to “do something about the lawn this year.”

Many home improvement stores take full advantage of this mindset by placing turfgrass seed and fertilizer products in locations that customers cannot miss. The sad reality is that spring is not the time to make major changes to tall fescue lawns in Tennessee. Any new plants established in the spring will be immediately faced with the stresses of heat, drought, weeds, and fungal pathogens in only a few short weeks when summer arrives. The time, money, and resources spent on spring establishment are far better spent in the fall.

That said, there are several things that homeowners can do to improve the quality of their tall fescue lawns during spring and summer. These tips are outlined below:

Far too often supplying lawns adequate nutrition is an afterthought. Many people forget that lawns are comprised of millions of individual plants that require adequate nutrition to grow optimally — just like the individual tomato or pepper plants that are installed in gardens every season. That said, lawns require fertilizer to perform optimally. What fertilizer is best? How much should be applied? Answers to these questions can be acquired via a soil test. University of Tennessee Extension can provide this service to homeowners for a small fee. After testing is completed, a slow release fertilizer can be applied such that nutrients will be slowly delivered over the course of the spring and summer season. More information on soil testing and fertilizer selection for tall fescue lawns can be accessed via University of Tennessee Extension.

Increase mowing height to improve the quality of tall fescue lawns in East Tennessee

Perhaps the easiest thing that can be done to improve the quality of a tall fescue lawn during the summer is to increase the height of cut. Tall fescue lawns should be maintained at 3 inches or higher for optimal performance. Far too often the opposite is true; homeowners mow their lawns as low as possible to increase the length of time between mowing events. This is a mistake. Leaf tissue is essentially the engine of a plant; leaves harvest light and turn that into energy via photosynthesis. The more leaf tissue present, the more surface area is available to capture light and turn that light into energy. The less leaf tissue present, the weaker plants become.

Tall fescue lawns can be plagued by annual weeds, particularly crabgrass (Digitaria spp.) during the summer. Crabgrass seed is abundant in many soils (particularly if this weed has been a historical issue in a lawn) and will germinate in spring when soil temperatures are warmer than 55F for several days. The blooming of forsythia can be used to indicate when this critical soil temperature threshold has been reached (Image 1).

Image 1- Blooming of forsythia at soil temperatures conducive for crabgrass (Digitaria spp.) germination in East Tennessee during spring.

Applying a preemergence herbicide in spring is an effective means of ensuring that a lawn won’t be overtaken by crabgrass over the course of a summer. Numerous products are available and testing at the University of Tennessee shows that these materials perform similarly when used according to label directions. The key is to ensure that these materials are applied to the lawn before crabgrass has emerged from the soil (i.e., “pre” = before; “emergence” = plants are visible). It is recommended that preemergence herbicides be applied to tall fescue lawns before border forsythia plants have lost their yellow blooms. Many of these products are sold on a fertilizer carrier which can allow homeowners to both supply nutrients to the lawn and control weeds. One key to improving the effectiveness of preemergence herbicide applications for crabgrass control is to ensure that products are watered into the soil (by irrigation or rainfall) within 48 hours after application. More information on crabgrass control in home lawns is available through University of Tennessee Extension.

Fall is the optimal time to make major improvements to tall fescue lawns across Tennessee, particularly establishing new areas from seed. The main reason for this is simple: newly established plants will have two seasons of optimal temperature conditions (fall and the following spring) to mature before they are faced with the stresses of summer. That said, use the summer to develop a plan for work to be conducted in the fall. It is recommended that homeowners pick a seeding date and work backwards when scheduling activities knowing that there will be several steps required in advance to prepare a site for seeding (e.g., non-selective herbicide application, vertical mowing, aerification, soil modification, pre-plant nutrition, etc). Additionally, those interested in establishing new turfgrass in their lawn should consult University of Tennessee Extension resources on new establishment of tall fescue. Always remember that “Fall is Turf Time in Tennessee.”

For more information on turfgrass weeds, please visit our website, tnturfgrassweeds.org



Professor, Univ. of Tennessee #Turf | #Grass | #Weeds | #Science | #Golf | #Sports | #Lawn | #Resistance | #Offtype IG: jim.brosnan.UT

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Jim Brosnan, Ph.D.

Professor, Univ. of Tennessee #Turf | #Grass | #Weeds | #Science | #Golf | #Sports | #Lawn | #Resistance | #Offtype IG: jim.brosnan.UT