About the Project

ReGrow Milkweed for Monarchs is a citizen science study testing ways to improve habitat for monarch butterflies.

adult monarch butterfly drinking nectar from milkweed flowerThe Eastern monarch butterfly migrates every year between wintering areas in central Mexico and summer breeding grounds in the Eastern US and Canada. Female monarchs lay eggs exclusively on milkweed plants, which are the only food their caterpillars can eat, while adult butterflies drink nectar from a variety of flowers. Monarchs have been declining for several years, and one of the ways people are responding is by planting milkweeds for monarchs to lay eggs on, and planting or encouraging other wildflowers for adults to use as a nectar source.

A new monarch conservation tool?

Young monarch caterpillars eat a regrowing milkweed stem

Researchers from MSU and elsewhere have discovered that we can improve monarch breeding habitat in a surprising way: by cutting back their host plant, common milkweed, during early or mid-summer and “regrowing” milkweed stems. This might sound strange, but the key is that milkweed has a huge root system and usually sends up new stems a few weeks after the old ones are cut back. Monarchs greatly prefer laying eggs on new milkweed stems over old ones, so the fresh stems coming up in July and August when undisturbed stems are getting older may be a very important resource. Regrown milkweed stems also appear to be a safer environment for eggs and young caterpillars. In part this is because new stems contain fewer of the spiders, ants, and other predators that usually eat monarch eggs and caterpillars. All in all, we think we may have found a useful way to improve monarch habitat -- by ReGrowing Milkweed for Monarchs!

We need help from citizen scientists!

We have researched ‘ReGrowing’ milkweed at several sites around East Lansing, Michigan with very promising results but now it’s time to scale up our study and see if it works in other settings. If you are in the Eastern US or Canada and have access to a patch of common milkweed, we need your help! We are asking participants in the project to cut back a portion of your milkweed in early summer and each week to compare the number of monarch eggs and caterpillars found on the regrowing stems and the ones you left alone. You can submit data using our ReGrow App, by filling out a form online, or with paper data sheets emailed to us. We will also ask about the tools you use to cut back milkweed (there are lots of options) and about the setting your milkweed patch grows in so we can learn more about when ReGrowing milkweed works and when it doesn’t.

How to get involved

If you would like to participate or learn more, sign up for email updates. We will use these to send you information about a webinar with more details on the project, as well as news and updates as we get ready for the experiment. We hope you’ll get involved! 

Sign up for email updates!


During May we will be gearing up for the project and getting citizen scientists oriented. Depending on your location, we will ask you to cut back some of your milkweeds at different points in June (earlier if you are further South, later if you’re further North). After your milkweed starts to regrow, we will ask for weekly updates during July and August on how many milkweed stems are coming up and the number of monarch eggs and caterpillars you find. We may also recruit participants to do additional milkweed cuttings in July so we can measure monarch use of the regrowing stems in August as well.

Want to know more?

For more detailed information, check out the For Citizen Scientists tab which has detailed instructions for participants, information on data sheets, etc. You can also check out our FAQ page or contact us with additional questions.

Here are some resources if you would like to learn more about monarch butterflies and monarch conservation in general.

        1. FWS save the monarch https://www.fws.gov/savethemonarch/
        2. Monarch Joint Venture https://monarchjointventure.org/ 
        3. MonarchWatch https://monarchwatch.org/
        4. Journey North https://journeynorth.org/


                                Monarch adult on milkweed