Research Update - Low Maintenance Turfgrass Evaluation Study – A cooperative project between University of Minnesota Extension and Hennepin County Environmental Services
Photo 1: Site conditions prior to low maintenance turfgrass installation, spring 2006. Bob Mugaas
Following is a brief report summarizing the results and observations regarding the establishment and growth of selected fine and tall fescue grass cultivars on an environmentally harsh site. It is located in Spring Park, Minnesota on the shores of Lake Minnetonka. Specifically, it is a nearly fully exposed south facing shoreline embankment between the Lake Minnetonka Sheriff’s Water Patrol (SWP) building and the Spring Park public access (PA). The southerly exposure and very poor, sandy to gravelly soil make this an intensely hot and very dry site. There exists a small lilac hedge along the very top (north) edge of the area adjacent to the parking lot. There are also several, poorly formed crabapple, green ash and Russian olive trees located on this site. All are less than 20 feet in height. Information regarding the establishment, longevity and competitiveness of these grasses on this site should be helpful to others managing similar types of sites.
This project was a cooperative effort between the Hennepin County Department of Environmental Services and the University of Minnesota Extension. Project managers from Hennepin County were Anthony Brough and Greg Senst. Regional Extension Educator, Bob Mugaas from University of Minnesota Extension, served as principal investigator for the study with cooperation from University of Minnesota Department of Horticulture Faculty member in turfgrass science, Dr. Eric Watkins.
Nature and Purpose of the Study:
Following several unsuccessful attempts to establish permanent, perennial, non-turfgrass vegetation on the above described site, the Hennepin County Department of Environmental Services contacted University of Minnesota Extension for advice and possible assistance in attempting to establish a very low maintenance turfgrass type groundcover on this area. From that request evolved an applied research/demonstration project evaluating whether or not a commercially available no-mow mix of several different fine fescue varieties could successfully be established and maintained on this site. The individual fine fescue varieties contained in the mix would also be evaluated independently in separate plots to assess their individual performance and potential contribution to the success (or failure) of the no-mow mix. Also included in the study was a seeded and sodded example of tall fescue. Seed for the no-mow mix along with the individual fine fescue cultivars and the tall fescue blend was generously donated by Twin City Seed Company. The rhizomatous tall fescue sod was donated by Glen Rehbein Companies. These industry contributions to the project were greatly appreciated.
Project Design and Installation
The specific varieties contained in the no-mow mix were ‘Defiant’ – hard fescue, ‘Celestial’ – creeping red fescue, ‘Intrigue’ – chewings fescue, and sheep fescue for which a variety was not specified. The tall fescue blend included the varieties ‘Millennium’, ‘Aztec II’, and ‘Anthem II’. The sodded cultivar is simply known as Rhizomatous Tall Fescue (RTF). With the exception of the sodded tall fescue, all other varieties were direct seeded April 25, 2006. The RTF sod was installed May 9, 2006. Plot sizes for the individual fine fescue cultivars and the tall fescue plots ranged from 400 to 600 square feet. The area seeded to the no-mow mix was about 1200 square feet in size. Once seeded, all areas were covered with Futerra™ erosion control mats to provide for a more uniform seed germination environment and help prevent soil erosion.
Turfgrass evaluation of the plots included both pictures and notes regarding establishment success, as well as color, density and overall quality of the planting as observed at various times during 2006 and 2007. Ultimately, information regarding the establishment, longevity and competitiveness of fine and tall fescues on very difficult sites was obtained and should be helpful to others considering use of the same plant material in similar situations.
Due to the very hot dry conditions during spring and early summer of 2006, regular watering was provided to ensure adequate moisture for germination and early seedling growth. Watering frequency and amount was significantly reduced during July, 2006 and eventually eliminated during August, 2006. Again, this practice was adopted in an effort to move toward minimal maintenance inputs on this site.
Photo 2: Two weeks following seeding. Note fine fescue seedlings growing through Futerra™ erosion control mats. Bob Mugaas
As this was a spring seeding, the potential for annual weeds to germinate, grow and potentially outgrow and out-compete the desirable grasses was high. Hence, regular mowing at about 3.0 to 3.5 inches was carried out through the middle of August, 2006 in an attempt to provide some level of weed suppression without resorting to the use of an herbicide. No further mowing was done on this site for the duration of the observation period as the ultimate goal was to have this be a no-mow area. An application of a broadleaf herbicide in the fall of 2006 was used to control developing perennial broadleaf weeds. No additional herbicides for either annual or perennial weeds were used in 2007. A turfgrass starter fertilizer was applied at the time of seeding. Also, plots did receive an application of nitrogen fertilizer at the rate of 1 pound of N per 1000 square feet in late October of both 2006 and 2007.
Results and observations summary
Futerra™ mats provided good protection from soil erosion and likely contributed to better initial establishment through greater uniformity of the seed germination environment. Supplemental irrigation can be extremely important in the early growth, establishment and even survival of spring seeded turfgrass. It can also be a means of moderating the effects of high temperatures. In this instance, the consistent watering provided by Hennepin County staff allowed for uniform germination and early growth of the seedlings thereby getting them off to a good start in spite of the prevailing hot, dry conditions during late spring and early summer. Where irrigation cannot be provided, the use of erosion mats such as those used in this study may play an even more important role in successful early turfgrass growth and establishment, especially for spring seeding.
Photo 3: Two months following seeding and before any significant summer drought stress. Foreground is the tall fescue seed blend with fine fescues behind. Bob Mugaas
Given the harsh conditions of poor soil and extreme exposure on this site, the fine fescues under a no-mow situation performed acceptably well and could be considered a good choice for providing soil stabilization and an appealing look to the area. However, one notable caveat is that in the full sun exposure of the southernmost 1/3 to 1/2 of the plots, some dieback of the fine fescues did occur. This was most likely due to the combination of high temperatures and dry conditions. This amount of injury would likely create the need for overseeding in order to preserve turfgrass density and limit future weed encroachment. For the purposes of this study, overseeding was not performed.
Photo 4: Poor recovery and growth due to heat and drought stress injury to fine fescues occurring during the summers of 2006 and 2007. Note healthier condition of fine fescue in partially shaded areas. Picture taken 8-31-07 Bob Mugaas
Where plots included some partial shading of the fine fescues, their performance was significantly better than on the more open, exposed portions. That observation is consistent with previously known information about fine fescues and reaffirms their successful adaptation to drier, partially shaded areas of the landscape (please see the last photo in the article).
In an effort to keep annual broadleaf weed competition from becoming excessive, mowing at about three inches was utilized during the early establishment period. Even though mowing heights were kept as high as possible, the extent of root development may still have been limited and perhaps contributed to the plant’s inability to survive the very hot dry conditions experienced from late spring through mid-summer of 2006.
Photo 5: Spring and early summer growth in 2008. Note the lack of flowering shoots (culms) in the shaded areas compared to those in full sun. Bob Mugaas
Because mowing is known to negatively impact turfgrass rooting, it may have been better to minimize or even eliminate mowing on this site and use an herbicide to manage potentially excessive weed competition early in the establishment period. This would have allowed the development of a deeper, more robust turfgrass root system and perhaps provided better tolerance, even survival, of the environmental stresses posed on this site. Hard fescue and sheep fescue are known to have very good to excellent drought tolerance and would be expected to survive and grow in relatively harsh conditions. However, all four of the fine fescue species/cultivars used in this study experienced difficulty in maintaining acceptable turfgrass density and growth where not partially protected by filtered shade from trees.
In addition to the mowing, there were relatively high levels of Canadian geese feeding on the lower two-thirds of most plots during the late summer and fall periods of 2006. Again, that kept plant heights very short, well below the three inch mowing height in some parts of the plots, and hence would likely had a negative impact on turfgrass rooting depth especially during the active root growth period of early to mid fall for our cool season turfgrasses. While all plots experienced at least some degree of geese feeding, it did appear to be less on the two tall fescue plots.
Photo 6: Acceptable to above average growth and recovery of seeded tall fescue plot during same time frame as in the fourth photo in this article. Picture taken 8-31-07. Bob Mugaas
The seeded and sodded tall fescue plots performed remarkably well with respect to their ability to tolerate and recover from hot dry conditions. Also, there appeared to be little overwintering injury due to lack of hardiness; a problem previously limiting the use of tall fescues in this region. In addition, there did not appear to be any particular advantage of using tall fescue sod versus seeding tall fescue under a Futerra™ erosion control mat. Ratings on all characteristics were similar throughout the course of the study.
There are many instances where poor site conditions create extremely difficult conditions for establishing any type of vegetative cover, including turfgrass. Results and observations from this study indicate that the use of fine fescue turfgrass species as well as certain varieties of turf-type tall fescue under no-mow practices could make acceptable or better plant material choices than what is typically used for these conditions. While both survived quite well in partially shaded conditions, the slightly lower temperatures along with reduced sunlight intensity clearly benefited the survival and growth of the fine fescues to a greater extent than the turf-type tall fescues. Future projects should continue evaluating turf-type tall fescues and fine fescues in these difficult environments. In turn, this will continue to build the data base of successful turfgrass species and essential cultural practices needed to establish low maintenance turfgrasses on these difficult sites near shorelines.