In 2016, U of M Extension Master Gardeners throughout Minnesota planted 24 varieties of annual flowers and observed pollinator activity throughout the summer as part of the 35th annual Master Gardener Seed Trial. Varieties included:
Volunteers were trained by extension educators and sent seeds to start on their own. Germination was challenging for some plants like Rudbeckia due to cool, wet weather. As plants started blooming, volunteers observed and counted pollinator visits to the flowers twice a week over eight weeks. Participants noted pollinator visits for each flower variety group over one minute, recording which pollinators landed on its flowers: honey bees, bumble bees, native bees, flies, beetles, butterflies / moths, and wasps. They also recorded weather conditions ( temperature, sun / clouds, wind).
Based on the volunteers’ recorded pollinator observations, the following varieties appeared most attractive to pollinator insects:
- Zinnias were by far the most attractive to
pollinators with a total of 1702 pollinator
visits across the four varieties. Noted varieties included ‘Pop art red & white’ (599 visits and ‘Envy’, a chartreuse flower. Hover flies (634) and native bees (320) were most widely observed on these flowers.
- Attractive marigolds included ‘Bambino’ (413) and ‘Tangerine dream’. Hover flies and native bees visited these varieties equally with approximate equal frequency.
- Salvia varieties (1024 total pollinator visits) that were most attractive to pollinators included ‘Coral Nymph’ (349 visits, 50% by hover flies) and ‘White swan clary sage’ (238).
- Attractive Rudbeckia varieties were ‘Irish eyes’ (543) and ‘Orange fudge’ (238).Hover flies and native bees comprised the majority of visitors (940 total pollinator visits).
- Sunflower variety ‘Lemon Queen’ (348) was visited most often and almost equally by honey, bumble and native bees. Sunflowers overall had 785 total visits.
- Snapdragons were the least visited of all varieties (436). The variety ‘Chantilly cream yellow’ was the least visited of all 24 varieties observed (73 visits, approximately 50% hover flies).