Mowing & Vegetation Management

INDOT maintains roadside vegetation along its limited-access, divided and rural state highways in an environmentally sensitive manner consistent with the special conditions presented by local climate, topography, vegetation and level of urbanization.

With more than 60,000 acres to maintain, INDOT is charged with balancing safety, expense and aesthetics when managing roadside vegetation. 

The purpose of vegetation management is to:

  • Enhance the safety of the motoring public
  • Enhance environmental protection
  • Mitigate erosion while providing adequate drainage
  • Encourage and maintain native wildlife habitats and native flora throughout the state

INDOT’s mowing practices are focused on maintaining vegetation at a safe height for driver visibility. In between mowing cycles, INDOT performs spot mowing to promote sight visibility at intersections or drainage. If grass or other vegetation is blocking intersection sight visibility, citizens are encouraged to report the area to the appropriate district.

Vegetation Management: A Plan Forward

INDOT’s vegetation management practices consist of the following elements:

Herbicide Treatments: As a member of the Indiana Invasive Species Council, INDOT’s goal is to eradicate invasive species and noxious weeds. By using a more stringent and uniform herbicide application process, our treatments will last two years as opposed to our previous one-year program. The first herbicide treatment addresses the typical weed growth, including broadleaf, clover, and dandelions. The second treatment targets invasive/noxious species, such as thistles, kudzu, and leafy spurge. With effective herbicide application, INDOT will improve roadside appearance and reduce costs.

Woody Plant Management: When crews are clearing brush and trees from along the roadways, they will treat the stumps to prevent re-growth.

Best Management Practices for Mowing: Mowingcrews will maintain a mowing height of 6-8 inches which will promote plant roots to develop that will help to reduct  erosion and the resulting thicker, and healthier, grass will better compete with undesirable 

Perfect our Timing: Crews will closely monitor the growth of the vegetation and time mowing cycles based on geographic location and weather. The first mowing cycle will be scheduled to take place after the rapid spring growth ends, except in areas necessary due tosight distance. Research has shown that delayingspring mowing schedules until after the grasses have reached maturity will prevent the grass from springing back up and limit growth for the rest of the season. INDOT crews  address sight distance concerns between mowing cycles, including the treatment of noxious species through herbicide application, to limit the spread of invasive and noxious weeds that grow tall and unsightly.

A Zoned Approach to Vegetation Mangagement: INDOT manages its limited-access, divided and rural state highways based on distance from road edge and based on roadway design. 

  • Zone 1, the roadway
  • Zone 2, Clear Zone and Median (if applicable): This clear zone extends from the edge of the shoulder pavement to 30 feet out. It also includes the grassy median, if applicable. This area is mowed most frequently and will also be treated by a selective herbicide treatment every two years to target invasive and noxious weed species.
  • Zone 3, Selective Zone: In areas where state right-of-way extends from 30 to 80 feet from the edge of pavement, INDOT will apply spot herbicide treatments to control invasive and noxious plants. These treatments will provide native plants more room to grow, and create more of a natural appearance. INDOT may mow this zone in urban areas if owners are maintaining adjacent properties.
  • Zone 4, Natural Vegetation: Where state right-of-way extends more than 80 feet from the roadway, INDOT allows for native plants and forestation to take hold and serve as a defense against invasive species. This area shields neighboring properties from the roadway and connects fragmented wildlife habitat.

Related Links 

Contact Information

Customer Service Department
Indiana Department of Transportation
100 N. Senate Ave., IGCN 755
Indianapolis, IN 46204