Slow Mow May

What is Slow Mow May?

Don’t spring into mowing too fast! For pollinators’ sakes, the Village wants you to take it slow for Slow Mow May by mowing less frequently (once every 2-3 weeks) this springtime.

In our area, pollinators start to emerge in early May. They rely on flower nectar and pollen for food, but floral blooms are scarce at this time. With reduced lawn-cutting, you are creating habitat and forage for the beneficial insects that desperately need our help due to the concerning trend of pollinator decline.

In 2023 from May 1 to June 1, the Village of Northbrook is suspending enforcement of the Municipal Code for excessive grass height and is encouraging all community members to participate in our "Slow Mow" initiative to voluntarily decrease mowing in support of wildlife. This may result in ground-cover exceeding the established ordinance height restrictions of eight inches, which is why enforcement is suspended for May.

How Can I Participate?

This year, community members are required to register to participate in Slow Mow May. There are two ways to register:

1. Email tessa.murray@northbrook.il.us with your property address.

2. Starting May 1, register in-person with the Development and Planning Services Department (second floor of Village Hall, 1225 Cedar Lane). To receive a “Slow Mow May” yard sign, you must register in-person.

Please note we are providing the signs only, garden stakes and zip ties are not provided.

“Slow Mow” vs. “No Mow”… What’s the Difference?

Last year, the Village participated in No Mow May, which is an international movement that discourages mowing for the entire month. Following review of the public comments received and further study of the research regarding pollinators and lawncare, the Sustainability Commission made the alternative recommendation in support of Slow Mow May.

To support pollinators, cutting your lawn once every 2-3 weeks is recommended. This is thought to be a middle ground where spring flowers can bloom, but grass is short enough that it is still navigable for insects to locate the flowers for food.

Unlike last year, registration will be required to participate. Enforcement of the grass height ordinance is waived until June 1 only for those who register.

What Grows When You Don't Mow?

When May lawn-cutting is delayed in Northbrook, you may find clover or common blue violets flowering in your yard. Our native bees rely on spring blooms for food and energy to start their colonies for the season. As scientists urge that the decline in insect populations is a concern for biodiversity, your yard can make a difference to help the survival of endangered species like the rusty-patch bumblebee!

Why Should I Help Pollinators?

Scientists project that the world loses 2.5% of insect mass per year. Pollinator decline refers to the reduction in populations of pollinating animals such as bees, butterflies, and birds, which are responsible for transferring pollen thereby facilitating reproduction of plants. This decline has been observed globally over the past few decades, and is alarming because pollinators play a critical role in maintaining the diversity and productivity of ecosystems, as well as the production of many crops that are important for food security.

Does This Really Help Pollinators?

Mowing your lawn less frequently allows pollinators to safely emerge and early-flowering plants to grow. The opportunity to establish beneficial insect populations (like our native bumblebees) is drastically reduced with early spring leaf litter removal and weekly grass mowing. However, a mere reduction in lawn-mowing is not the end-all be-all of supporting our local ecology.

The typical suburban landscape is considered a monoculture dominated by a single species or a few species of non-native plants, such as Kentucky bluegrass or Bermuda grass. Our native wildlife rely on plant species they co-evolved with for successful nutrition and habitat, so planting native supports the overall ecosystem. (Note: Northbrook’s grass height ordinance only applies to non-native grasses. Native grasses like bluestem, sedges, and ryes may grow to any height unless they are planted in an area that could interfere with visibility of motorists).

Beyond reduced mowing, much can be done in support of pollinators on all or a portion of your yard:

Incorporate a range of native plants with a succession of bloom times to provide floral resources spring through fall. Some great choices are bee balm, foxglove, and goldenrod.
Commit to low or no use of pesticides, which can kill or weaken pollinators’ ability to reproduce.
Leave fallen tree leaves and dried-up vegetation for birds and nesting insects like dragonflies and butterfly chrysalises.

FAQs

Who does this apply to?

Any Northbrook community members who register with the Village may participate, with the exception of HOA residents if they have conflicting regulations.

Why is Northbrook doing this?

Northbrook committed to the initiative because of community concern about declining populations of wildlife due to habitat loss. “Slow Mow May” is to allow pollinators to safely emerge and early-flowering grasses and forbs to grow. The opportunity to establish beneficial insect populations like our native bumblebees is drastically reduced with early spring grass mowing.

Is there evidence that reduced mowing helps pollinators?

The general consensus among researchers is that mowing every 2 or 3 weeks is best for pollinators. A 2018 study from the journal Biological Conservation tested several mowing frequencies in suburban spaces as they relate to pollinators, which found that mowing every two weeks may be more beneficial than a total month-long reprieve, as insects have a more difficult time finding flowers surrounded by tall grass. Mowing once every two weeks is considered a “happy medium” where flowers can establish and are still accessible to pollinators.

Additionally, it's also important to ensure that you are mowing your lawn properly to prevent harm to pollinators. This includes mowing at a higher height, using a sharp blade, and avoiding mowing during times when pollinators are most active, such as early morning or late evening.

Can I only do a portion of my yard?

Yes, every little bit helps!

What if I think my grass is getting too long?

You can mow some of it or all of it! This initiative is about habitat, but also about bringing attention to how we, as stewards of the land, can do things better, not only for pollinators, but also for ourselves. Studies indicate that the optimal mowing cycle to specifically benefit pollinators, is every two weeks.

Dandelions are non-native weeds, why should I let them grow?

Do what works for you! The following answer is in regard to how to best support pollinators:

If you have native landscaping but there are dandelions growing that may outcompete your native species, you should cut them!

If you and a lot of your neighbors have a classic turf grass, then wildlife will indeed use dandelions for food and nesting materials. Birds use dandelions for nests, and bees will gather dandelion pollen when other pollen is not available.

To learn more, refer to this article from the University of Illinois.

What should I do about dandelion seed heads in my yard?

You can cut them. Dandelion seed heads have no further benefit to pollinators, so cut them down, but cut them high, as to not mow other flowers below them.

My neighbor is participating, and I don't like it.

The natural aesthetic can take a bit of getting used to. Feedback on this program, both positive and negative is welcomed. Email sustainability@northbrook.il.us.

What about ticks?

Ticks that carry Lyme disease are more likely to be found along forest edges compared to our residential lawns, but they can be found wherever there are suitable hosts. Because a benefit of natural landscaping is that it provides habitat for wildlife, attracting insects will also attract insect-eaters. As Northbrook continues to restore healthy ecosystems with sustainable practices, more tick-eating animals like birds and amphibians will be present. The best prevention against Lyme disease is proper clothing and a careful check of body and clothes after being in an area likely to have ticks.

What happens after Slow Mow May for enforcement?

Participating properties are expected to comply with ordnance when the enforcement pause ends on June 1. The maximum height with enforcement is 8 inches. Enforcement of the grass height ordinance begins again in June. The ordinance is enforced by municipal code officers in the Department of Development and Planning. The process is as follows:

Someone files a complaint on a property for violating the municipal code. This can be done online or by calling 847 664 4050.
Municipal code officers confirm the violation and send a letter that notifies the property owner that a complaint has been filed and that they must mow within 5 days.
Municipal code officers revisit the property to ensure the violation is resolved. If it is not, the Village will send out our landscaping contractors to mow, and the property owner is charged for this service.

What else can a property owner that cares deeply about pollinators be doing?

Leave your leaves in the fall – they provide habitat for overwintering species; or if there are too many in certain spots, gather some and mulch them with your lawn mower
Leave perennials standings when perennials die back in the fall; the stems provide shelter for insects and the seed heads provide food for birds
Avoid using pesticides and herbicides - lawns may support diverse plant communities and floral resources if we refrain from using herbicides to kill 'weeds' such as dandelions and clover
Plant native plants whenever you can - either in a dedicated space or interplanted with ornamentals and non-natives
Grow flowering plants in groups is more impactful than spacing them far apart
Plant a wide variety of flowering plants that bloom at different time throughout the year so that there will be something for pollinators from spring through fall
Plant trees, herbs, flowering fruits and vegetables, natives are best for wildlife, but as long as you avoid invasive species you will be providing habitat
Leave some areas, even small areas, undisturbed- long grass, log piles, brush piles for winter shelter for insects that later provide high protein for birds
Only fertilize your lawn when necessary rather than routinely, organic products preferred
Create nesting shelter for birds

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