In the fall of 2018, our team completed another field season tracking the environmental horticulture plants that are visited by pollinators. Some preliminary patterns are now starting to emerge, with a few plant species appearing to be highly attractive to pollinators, but many other plant species are not-at-all attractive to pollinators.

Cultivars matter when it comes to pollinator attractiveness, image shows one Agastache species received an average of one bee visit per week, while another cultivar received an average of 25 bee visits per week.

In California, for instance, the annual plants frequently visited by bees were sweet alyssum and California poppies. Some of the perennial plants frequently visited by bees were catmint, Russian sage, asters, and fleabane. Annuals mostly received visits from non-bee pollinators, such as ants, small wasps, and flies, while the perennial plants were more visited by bees.

In South Carolina, last summer was dry and hot, and as a result fewer pollinators were observed in 2018 than in 2017. There was a great deal of variability in the numbers and types of pollinators visiting each plant species between the two years. In these South Carolina plots, moss rose (Portulaca) had the most native bees visiting it in both 2017 and 2018.

In Pennsylvania, the team tested five different species of flowers, and also tested various cultivars of each species. Different cultivars of the same plant species have had widely different numbers of pollinators attracted to them. One cultivar of Agastache spp., for instance had an average of 25 pollinators visits every 10 minutes, while a different cultivar of Agastache spp. had an average of only 1 pollinator visit every 10 minutes!

Researchers: Drs. Jim Bethke, Christine Casey, JC Chong, Christina Grozinger, Harland Patch, Dave Smitley, Kim Stoner

States: CA, CT, MI, PA, SC