2017 ASHS Annual Conference

Wildflower establishment for pollinator habitat and other ecological services are of growing interest to landowners, farmers and landscapers. Weed competition is a major impediment to establishing a dense, diverse planting of native perennials and warm season grasses. We compared spring and fall planting dates and the use of seeds versus plugs as planting materials to determine their effects on weed and wildflower competition over a span of five years. A mix of 18 perennial forbs plus four grasses was used in all plots. Site preparation methods consisting of herbicide applications, tillage, or smothering with black plastic were employed for three months in the summer prior to fall planting. Spring plots received a single herbicide application or tillage or herbicide plus tillage, one to two weeks prior to planting. The experiment was a split-plot design with planting dates as main plots. Planting materials and site preparation treatments were randomly assigned in two complete blocks within each main plot. Crabgrass and other annual weeds severely inhibited forb growth in spring seeded plots, but mid-summer mowing allowed for wildflower establishment and recovery in the following year. Plugs had long-lasting negative effects on forb density, but positive effects on species diversity, compared to seeds. Fall seeded treatments had high wildflower density but lower diversity than spring seeded treatments. Subplot site preparation treatments had no lasting effect on density or diversity.