Presentation Title

Which native plants should home gardeners grow for pollinators?

Start Date

3-2-2020 12:00 AM

Abstract

Many published pollinator-friendly planting lists lack empirical evidence to support recommendations. To address this, in 2017-2019, we screened 23 native Willamette Valley wildflowers. Plants were selected based upon their potential use in ornamental gardens, as well as anecdotal reports of attractiveness to pollinators. We included four exotic comparators known to be attractive to pollinators. Species were planted in meter-squared plots spaced six meters apart. Between April and October, we monitored pollinator visits, floral bloom phenology, and sampled insects from plots, weekly.

We have early findings on the attractiveness of these wildflowers to bees. The most attractive plants varied between the three years, possibly due to differences in phenology and plant establishment. In 2017, four native wildflowers (Solidago canadensis, Symphyotrichum subspicatum, Clarkia amoena and Gilia capitata) were the most attractive flowers for bees, followed by the exotic Nepeta cataria. In 2018 and 2019, three of the six most attractive plants to bees were exotic species. However, this pattern was strongly driven by European honey bee visitation. When we limited our analysis to native bee abundance, the six most attractive wildflowers were all native species. Similarly, across all seasons native wildflowers attracted the highest native bee species richness.

To address suitability for urban landscapes, we surveyed gardeners for how aesthetically pleasing they find these 27 plants. Additionally, we surveyed whether gardener preferences can be influenced by the ecological benefits that flower species provide. We found that after education on pollinator visitation, respondents viewed flowers as 40%-80% more attractive.

Subjects

Conservation biology, Habitat restoration

Persistent Identifier

https://archives.pdx.edu/ds/psu/33829

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Feb 3rd, 12:00 AM

Which native plants should home gardeners grow for pollinators?

Many published pollinator-friendly planting lists lack empirical evidence to support recommendations. To address this, in 2017-2019, we screened 23 native Willamette Valley wildflowers. Plants were selected based upon their potential use in ornamental gardens, as well as anecdotal reports of attractiveness to pollinators. We included four exotic comparators known to be attractive to pollinators. Species were planted in meter-squared plots spaced six meters apart. Between April and October, we monitored pollinator visits, floral bloom phenology, and sampled insects from plots, weekly.

We have early findings on the attractiveness of these wildflowers to bees. The most attractive plants varied between the three years, possibly due to differences in phenology and plant establishment. In 2017, four native wildflowers (Solidago canadensis, Symphyotrichum subspicatum, Clarkia amoena and Gilia capitata) were the most attractive flowers for bees, followed by the exotic Nepeta cataria. In 2018 and 2019, three of the six most attractive plants to bees were exotic species. However, this pattern was strongly driven by European honey bee visitation. When we limited our analysis to native bee abundance, the six most attractive wildflowers were all native species. Similarly, across all seasons native wildflowers attracted the highest native bee species richness.

To address suitability for urban landscapes, we surveyed gardeners for how aesthetically pleasing they find these 27 plants. Additionally, we surveyed whether gardener preferences can be influenced by the ecological benefits that flower species provide. We found that after education on pollinator visitation, respondents viewed flowers as 40%-80% more attractive.