Roadsides can be difficult environments for plant establishment, but site preparation techniques can help improve plant survival and establishment. To improve roadside plantings in the state of Michigan, we investigated the impacts of site preparation and evaluated plant selections in collaboration with the Michigan Department of Transportation. We conducted a large-scale field study at two locations (Warren, MI and Roseville, MI) along I-696 near Detroit, MI. The objective of the site preparation study was to evaluate the effect of site preparation (tillage and addition of compost) on establishment of roadside plantings. 16 selections of shrubs, perennials and grasses were planted in four site preparation treatment. In a supplemental plant evaluation study, the establishment and survival of 16 additional plant selections. In the site preparation experiment, compost application had positive effects on plant growth and ground cover in 2019 and 2020, however compost did not affect plant survival in either year. Possible aspect effects were observed as well. Overall, shrubs had increased rates of survival and groundcover when compared to perennial plants. Plant selections that had no mortality in 2020 were Hemerocallis ‘Happy Returns’, Hemerocallis ‘Stella De Oro’, Amsonia hubrichtii ‘Halfway to Arkansas’, Diervilla sessilifolia ‘Butterfly’, and Cephalanthus occidentalis ‘SMCOSS’.
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