Spring has come early to the mid-Willamette Valley! As you start planning your garden, take time to read this article first, for the research on the most effective way to plant milkweed for monarch butterflies. You may even want to transplant some of your current milkweed plants after you read this. In summary, the outer edges are better.
Link to full article
Excerpted from "How Do Your Milkweeds Grow?"
Donald Lewis, Department of Entomology
Horticulture and Home Pest News
Iowa State University Extension and Outreach
Landscape architects and garden designers might disagree with Contrary Mary’s arrangement of flowers in a perfect row, but maybe it makes sense to monarch butterflies.
A recent publication by Adam Baker and Daniel Potter of the University of Kentucky reported that monarch eggs and larvae were 2.5–4 times more abundant in gardens where milkweeds were evenly spaced around the perimeter of the garden rather than intermixed with other nectar plants and grasses. You can read the full publication, Configuration and Location of Small Urban Gardens Affect Colonization by Monarch Butterflies in Frontiers of Ecology and Evolution, 05 December 2019 here: https://doi.org/10.3389/fevo.2019.00474.
The researchers established replicated gardens containing the identical mix of milkweeds, flowering nectar sources, and non-host ornamental grasses but arranged in three different spatial configurations as shown below.
Link to full article which has much more information and helpful links.
These posts are from Master Gardeners, as well as speakers we have had at various events concerning pollinators.