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Roadsides are a unique growing environment for turfgrasses and can be a challenge to establish and maintain. The University of Minnesota turfgrass research program has been investigating low-input turfgrasses that are better adapted for roadsides and our previous research project identified a new mixture for use on Minnesota roadsides that was able to perform adequately under pressure form road salt (MNST-12). As this new mixture was used; it became apparent that more research was needed to better understand how to improve establishment and performance by adjusting typical roadside maintenance practices. In this project; we developed a series of experiments addressing three areas: (1) pre-establishment soil amendments; (2) planting date; and (3) watering during establishment. We found that soil amendments had little effect on roadside turf performance. We found that seeding of low-input roadside mixtures such as MNST-12 should be performed in late summer; while sodding can be done throughout the growing season; assuming that soil moisture is properly maintained. Finally; based on our findings; we recommend that current MnDOT specifications for watering of new roadside turf installations should be changed; especially for mixtures with high proportions of fine fescue.

Roadsides are a challenging environment for successfully establishing turfgrass. Site-specific stresses demand multi-site testing of grasses and grass mixtures. This study evaluated 60 entries that varied by cultivar; species; or mixture by establishing on-site trials in MI; MN; NE; NJ; and WI. The entries tested included 50 individual cultivars and 10 standard mixtures; two from each participating state based on their current specifications. One location in each state was along an urban or suburban street with a curb; while the second location was along a rural highway without a curb having a ditch that slopes away from the road with a daily traffic volume of at least 30;000 vehicles. Plots were seeded at most sites in late summer 2016; and data were collected through spring 2018. Turfgrass performance was assessed by counting living turf cover; weed cover; and bare soil using the grid intersect method in the spring and fall of each year. Species and cultivar performance varied among locations. Several species showed potential for inclusion in effective mixtures. Other species performed well at some locations and poorly at others. Performance of standard mixtures was also inconsistent across locations. This research demonstrates the need for locally generated data on roadside turfgrass performance.

Our project was based on the need to water new roadside installations more efficiently to ensure that the turfgrasses; especially the new salt-tolerant mixes; establish more successfully with a predictable and uniform amount of water during the establishment period. The first objective of this project was to do a preliminary investigation of alternative means of irrigating new installations of salt-tolerant seed and sod mixtures. We completed the testing of four drip-tape-style irrigation systems placed both above and below sod; two above-ground sprinkler system configurations; and eight water truck nozzles. We then evaluated these new irrigation methods compared to current practices. We also developed an online voluntary training and education program for installers of roadside turf. And finally; we developed online maintenance training for homeowners to maintain new roadside turf installations. Based on our research; we recommend the use of 18-inch (45.7-cm) irrigation tape laid above the germination blanket (when seeding); or above sod when using a hydrant adapter with a programmable irrigation system as this system is easier and cheaper to install; can be removed and possibly reused after establishment; and results in reduced water use.