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Be a Smarter Gardener in 2019: Is a Cultivar as Good as the Native Plant Species for Pollinators?

Bumble bee on blue giant hyssop
Photo by Julie Weisenhorn
The short answer is, “it depends.” Some cultivars are better than their native species, some are no different and some are worse at attracting pollinators. Each plant should be considered on its own merits. 

As a gardener, you can compare an ‘improved’ cultivar to its wild species in your own garden. 

Cultivars vs. Natives in Vermont

When Annie White was a PhD graduate student at the University of Vermont, she compared several native species to cultivars. For two years in two locations, she counted all pollinators--her results are summarized below. 

She counted all insects and grouped them into broad categories. She included all bees, native and otherwise, butterflies, flies, beetles, etc. that were found foraging on the flowers. 

The total number of insects is amazing! And what a difference between the New England aster and wild indigo! Some of the cultivars attracted more insects than the species of other flowers. 

Below is a list of plant species and respective cultivars researched by White in 2016. The total number of pollinators (bees, butterflies, wasps and flies) are listed after each plant name. 

Species: Achillea millefolium, common yarrow -1414*
Cultivar:  'Strawberry Seduction' - 119

Species: Agastache foeniculum, blue giant hyssop - 973*
Cultivar: 'Golden Jubilee' - 566

Species: Asclepias tuberosa, butterfly weed 230 no difference
Cultivar: 'Hello Yellow' - 331
 
Species: Baptisia australis, wild or blue indigo - 182 *
Cultivar: ‘Twilite' Prairieblues - 78

Species: Echinacea purpurea, purple coneflower - 729
Cultivars: ‘Pink Double Delight’ - 94; ‘Sunrise’ -112; ‘White Swan’ - 404

Species: Helenium autumnale, common sneezeweed - 1,887*
Cultivar: 'Moerheim Beauty' - 222

Species: Monarda fistulosa, wild bergamot - 877 no difference
Cultivar: 'Claire Grace' - 660

Species: Penstemon digitalis, beardtongue - 229 no difference
Cultivar: 'Husker Red' -147
Species: Rudbeckia fulgida var. fulgida, black-eyed Susan - 119 no difference
Cultivar: 'Goldsturm' -120

Species: Symphyotrichum novae-angliae, New England aster - 2,100*
Cultivar: 'Alma Potschke' - 234

Species: Tradescantia ohiensis, spiderwort - 552* 
Cultivar: 'Red Grape' - 279

Species: Veronicastrum virginicum. Culver's root - 616
Cultivar: ‘Lavendelturm’ -1,347*

*This plant was significantly better than its paired comparison; four pairs had no significant difference within the pairs.


Today's Research

Bee favorite Music box mix sunflower
Photo by Julie Weisenhorn
Plants are different and the insects can tell this! So we continue to do more research on this topic. Each plant species is unique and should be considered on its own merits.  

University of Minnesota Horticulture Extension Educator Julie Weisenhorn continues to research this topic using several annual flowers at multiple locations in Minnesota and Wisconsin. This study is funded by the Horst M. Rechelbacher Foundation.

More on Weisenhorn's work: 
Flowers for Pollinators blog 
U of M Plant Education Group
Growing Landscapes to Help Bees and Pollinators 

Resources

For more information: 
White, A. 2016. Pollinator Gardens. Accessed 10 Jan 2019. https://pollinatorgardens.org

White, A. 2016. From Nursery to Nature: Evaluating Native Herbaceous Flowering Plants Versus Native Cultivars for Pollinator Habitat Restoration. Accessed 8 January 2019. <https://scholarworks.uvm.edu/graddis/626/>.

Authors: Mary Meyer, Extension Horticulturist; Julie Weisenhorn, Extension Educator


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Comments

  1. It would seem to me the issue is whether there is nectar and / or pollen for the pollenators.
    Also, I think one thing missing from the conversation is the resilience of sexually propagated (seed) vs asexually propagated ( cloned cultivars).

    ReplyDelete
  2. Yes, you are correct. If there is no nectar or pollen, insects get nothing, so they stop going to these flowers.
    Propagation method is not so important here....its in the genes in the plant that matter. So, plants propagated by vegetative means, division or corms, like Liatris spicata Kobold, cannot affect the amount of nectar in the flowers. Seed propagation allows for the variation of individual populations and as such individuals may vary in their nectar content or pollen amount, perhaps that is what you mean. Seed propagated individuals may have different amount of nectar and pollen even though they are all Liatris spicata, but on the whole they will have more than Kobold, as that cultivar has limited pollen and nectar for insects.

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