Mowing for Monarchs 101

Gardens, lawns, fields, roadsides, right-of-ways all provide vital habitat for monarchs and other pollinators. How we manage this habitat must be done with care to help protect our monarchs!

Mowing too frequently or when it is poorly timed can be detrimental to the monarch population. However, according to a recent article in the Global Ecology and Conservation, strategic mowing can be beneficial to monarch populations when it produces young milkweed plants at the right time.

The key to understanding when  to mow is knowing when the monarchs are present in your area so you can better time your land management practices.  For instance, if mowing occurs when there are monarch eggs, larvae or adults present on the milkweed, this will have a negative impact on monarch populations. This also applies to other land management practices such as controlled burns, targeted pesticide application and grazing. 

The following recommendations will help you to time your land management practices so that the least amount of harm is done to our monarch populations. 
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For more information, read Mowing and Management: Best Practices for Monarchs by Monarch Joint Venture. 

When are monarchs present in my area?

Journey North reported Monarch sightings

Timing is crucial when planning your mowing and other land management practices. To find out where the monarchs are, you can view up-to-date monarch observations at Journey North or Western Monarch Milkweed Mapper.
Remember that this will vary each year. 
In addition, you can conduct your own survey by checking your milkweed patch/field daily.
Once you understand where the monarchs are and when they will be visiting your habitat, you can create a strategic mowing plan. 

Monarch butterflies are often observed in the grasslands of Floyd Bennett Field. NPS Photo

Limit the frequency of your mowing

Mowing milkweed mid-summer in areas where there is a lull in monarch activity, such as the Southern Great Plains, may promote milkweed growth and late summer or early fall breeding (Baum and Mueller 2015; Fischer et al. 2015). Always, do a quick survey for monarchs before mowing and check Journey North's website to see where the monarch is in their migration. 

Leave a pollinator refuge area 

Instead of mowing the entire area, leave refuge areas that may be good for nesting or overwintering sites for pollinators and other wildlife. If necessary, make a sign that indicates that site is an overwintering refuge. 

Avoid mowing milkweed and blooming flowers

Blooming flowers provide essential nectar sources for pollinators. In addition, check to see if the flowers have began dispersing their seeds. 

Increase your cutting height

Increasing your cutting height by a few inches will remove the seed heads of the invasive plants while still providing some habitat for other bugs and pollinators to thrive. 

Sources

Fischer, S. J., Williams, E. H., Brower, L. P., & Palmiotto, P. A. (2015). Enhancing monarch butterfly reproduction by mowing fields of common milkweed. The American Midland Naturalist, 229-240.
Chicago

​Habitat Enhancement and Best Management Practices in Highway Rights-of-Way.” Prepared by The Xerces Society for Invertebrate Conservation in collaboration with ICF International. 68 pp. Washington, D.C.: Federal Highway Administration.

Journey North. journeynorth.org/monarchs

Knight, S. M., Norris, D. R., Derbyshire, R., & Flockhart, D. T. (2019). Strategic mowing of roadside milkweeds increases monarch butterfly oviposition. Global Ecology and Conservation, 19, e00678.
Chicago

Monarch Joint Venture. Mowing and Management: Best Practices for Monarchs. 
https://monarchjointventure.org/images/uploads/documents/MowingForMonarchs.pdf

Western Monarch Milkweed Mapper. ​https://www.monarchmilkweedmapper.org/