Planting for Success: How to Incorporate Milkweed into Your Garden
As the summer breeding season continues for much of North America’s migratory monarch population, butterfly watchers can watch for the second and third generations of monarch butterflies in your area. While fourth-generation monarchs comprise the migratory population each fall, the second and third ‘middle’ generations comprise the summer breeding season. During this mid-season period, monarchs live for just 2-5 weeks; instead of the 8-9 months the migratory generation persists.
Although planting any amount of milkweed is helpful to the monarch population, the question of the best milkweed species and how to arrange a garden to attract monarchs has become of interest to monarch researchers. For one researcher in particular, Dr. Adam Baker, these questions became one of the primary drivers of his Doctoral Research at the University of Kentucky. In this edition of the Pollinator Chronicles, we will look into some of his exciting monarch and milkweed research findings.
Milkweed Used:
Alongside advisor Dr. Daniel Potter, Baker recognized the ‘buzz’ around monarch-targeted gardening and how meaningful backyard pollinator conservation could be. To harness this energy further, Baker studied the most successful ways to incorporate milkweed into backyards or urban gardens. He examined eight milkweed species (Aslepias spp.) during his study. Common (A. syriaca), swamp (A. incarnata), butterfly (A. tuberosa), green (A. viridis), and whorled (A. verticillata) milkweeds are all native to the study area of Lexington, Kentucky, and were included in the trials to determine which was most readily used by monarchs for egg-laying. He also included showy (A. speciosa), narrowleaf (A. fascicularis), and broadleaf (A. latifolia) milkweeds into the study gardens. (Baker 2018). Baker tallied monarch eggs and larvae on the plants in his research gardens over several growing seasons to determine which milkweeds were the most attractive to egg-laying monarchs.
Findings:
- Good news for those who prefer varied milkweed – all eight species demonstrated caterpillar growth and development once inhabited by monarchs.
- Egg-laying adult monarch butterflies preferred taller species of milkweed. Swamp, common, and showy milkweed all have broader leaves and tend to grow to taller heights, which appeared to result in more significant numbers of eggs and larvae counted on these species.
- For those interested in attracting other pollinator species to their garden, it is notable that butterfly and narrowleaf milkweeds attracted the highest number of bees to the garden plots.
- The study found that butterfly, narrowleaf, and whorled milkweeds benefitted from the highest bee diversity among all the blooming milkweed species (Baker 2018).
Garden Design:
Another important aspect of Dr. Baker’s research was the investigation of garden design. While most gardeners already consider factors like sunlight and soil needs when selecting a plant’s location, Baker wanted to determine whether a particular garden layout might increase the likelihood of egg-laying by monarchs. After testing several variations of garden layouts:
- Milkweed on the perimeter, with nectar plants in the center
- Milkweed in the center, with nectar plants along the perimeter
- An unstructured garden
Dr. Baker was able to draw some important conclusions (Baker 2019).
Garden Results:
- Monarch butterflies laid more eggs on milkweed in the gardens with milkweed on the perimeter.
- Baker found eggs or larvae more likely on host plants laid out in a manner that made them as obvious as possible to the searching monarchs.
Garden Recommendations:
- Spacing out other plants from milkweed by several feet will keep them from overcrowding the milkweed.
- Mulching (where possible) around milkweeds in your garden will make them stand out in the landscape.
It’s all about making the milkweeds as apparent as possible to monarch adults that may be flying by, ready to lay eggs! The diagram below shows what this type of garden design might look like with milkweeds surrounding the exterior of the plot and nectar plants in the center:
Exciting Discovery:
Dr. Baker’s study found that monarch butterflies ready to lay eggs discovered waystations of all different sizes, making it one of the most exciting findings of the milkweed colonization study. This finding means monarch butterflies are attracted to milkweed planted in small urban garden patches and larger rural fields – any bit helps! This discovery is great news for gardeners of all capacities. Planting milkweed for monarchs can be successful across a host of different landscapes. How exciting that scientific literature now supports a sentiment echoed by monarch enthusiasts and gardeners: If you plant it, they will come!
Building a Better Monarch Waystation (More from the study)
More Monarchs & Milkweed:
- Monarchs’ Journey North: How You Can Help Boost Their Numbers
- Preparing Your Pollinator Garden for Spring
- Monarch Protection
- Monarch Habitat
Articles Referenced:
Baker, A. M and D. A. Potter. 2018. Colonization and usage of eight milkweed (Asclepias) species by monarch butterflies and bees in urban garden settings. Journal of Insect Conservation, 22(3), 405-418.
Baker, A. M. and D. A. Potter. 2019. Configuration and location of small urban gardens affect colonization by monarch butterflies. Frontiers in Ecology and Evolution, 7, 474.
Baker, A. M. and D. A. Potter, D. A. 2019. Building a Better Monarch Waystation. Entomology 2019. ESA.
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