Annual flower strips increase biodiversity even if planting is delayed

Flower strips are an effective way to enhance agroecosystem biodiversity and ecosystem services. Most flower strips are composed of perennial species. Despite their ecological benefits, perennial flower strips are not widely adopted. Barriers to adoption include the long-term commitment required and concerns about weeds. This study explores whether annual flower strips might be feasible for more farmers. We conducted an on-farm experiment on five commercial farms in New York, USA. On each farm, we established four treatments. At maize planting time, we seeded an early-established planting (EP) treatment with a commercial mix of annual flowers. An early-established control (EC) was set up at the same time with no seeding. Four weeks later, we prepared a new seedbed for late-established planting (LP) and late-established control (LC) treatments. We observed significant effects of planting on plant species richness and Shannon diversity (F-test, p < .001). Planted treatments were more diverse than control treatments. However, there was no effect of establishment time on diversity. Both planting (F-test, p = .004) and establishment time (F-test, p = .04) affected the number of dicot species at the flowering stage, which was highest in the EP treatment. This flowering species richness was positively associated with spider abundance in sweep-net samples. Overall, our results demonstrate that annual flower strip establishment is possible even under weedy conditions. In addition, they show that a delay in planting date does not eliminate the benefits of this practice. This information could help farmers make informed, site-specific decisions about whether flower strips are a good fit for their farms.