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Low Mow Policy for City Parks and Open Spaces

For many years, the City of Westminster has mowed many natural areas on parks and open space properties. While mowing will continue in certain areas, notably close to trails and other amenities, the City is adopting a “Low Mow” practice for much of our natural areas. There are many benefits to this new approach, including enhanced stormwater drainage management, water quality, supporting local plants and wildlife, and lowering fuel emissions from less time running equipment. Other neighboring jurisdictions, including Greeley, Brighton, Arvada, Lafayette and Broomfield, have successfully implemented similar policies in recent years.


Maintained Turf Grass

High traffic tolerance The preferred aesthetic requires: Mown every 5-10 days, May-Sept
Adapted to constant, low mowing
  • 750k-1m gallons per acre annually

Irrigation cycles from May-Sept:

  • Sports turf fields - Dense, green turfgrass
  • Aesthetic lawns - Sustain turf cover; grass will dry in the heat of summer and rebound with precipitation
Desirable green color and fine leaf blade
  • Ongoing fertilizer and pesticide applications

Pest control is handled with similar thresholds as irrigation:

  • Sports turf fields will have a smaller tolerance for turn disease or weeds
  • Some pests/weeds will be tolerated and only managed when significant loss is likely
Adequate ground cover for erosion control
  • Ongoing thatch management

Cultural Practices

  • Fertilized 1-2x annually
  • Aerated a minimum of 1x annually, site dependent
  • Overseeded only to repair thin or dead turf
Cheap to install
  • Susceptible to winter kill in our climate
  • Monoculture; offers zero diversity or habitat to the ecosystem


Native Grasslands - Mowed

Naturally adapted to our climate Lacks the aesthetic of bluegrass Mown every 3-6 weeks, May-Sept
Green aesthetic with supplemental irrigation Poor recuperative ability, less suited to trafficked areas than bluegrass Irrigation is not typically available for forage grasses
Deeper rooted than bluegrass Shallower rooted than unmown forage grasses If irrigation is available, cycles will not exceed 1 day/week
Lower ongoing management (pesticides and fertilizer inputs) than bluegrass More prone to weed invasion and thus reliant on herbicides Pest control is performed by mechanical means, typically mowing
Reduction in carbon footprint over a manicured landscape Neutral diversity offering, minimal habitat opportunity If chemical pest control is deemed necessary, timing will be site dependent
Cost effective ground cover for erosion control or unirrigated ROW, trailsides    


Native Grasslands - Unmowed

Fully adapted to our climate Aesthetic is often referred to as unkempt or neglected Mown only if prescribed by staff for effective management
Minimal inputs required once established Invasive species can become an issue if not managed Commuter trails receive edge mowing every 3-6 weeks to maintain safe travel ways
Excellent groundcover for erosion control and water quality features Wildfire or grassfire potential Where appropriate and consistent with land management goals, fenceline edges are mowed every 3-6 weeks
Positive diversity, offers significant habitat opportunities   Irrigation is not typically available for forage grasses
Net positive carbon footprint vs a manicured landscape   Pest control is performed by mechanical means, typically mowing
    If chemical pest controls are deemed necessary, timing will be site dependent



By allowing native plants to grow and reach maturity, flowers bloom and attract pollinators. Pollinators thrive off of these native plants and then in turn support local farmers and gardeners. Native bees and other beneficial insects feed off of these flowers and find shelter in the tall plant life. Monarch butterflies have been impacted by heavy mowing of natural areas as they rely on milkweed plants to lay their eggs and feed their larvae. Leaving natural areas to grow with minimal human intervention allows these and other animals to thrive in our community.

Strong native plant communities also help prevent erosion. Unlike turf or mown fields, mature native plants grow deep roots that hang onto soil even during heavy rainfall events.  Locations with a high density of mature native plants, those who have not been cut down by mowing, also retain water and help the ecosystem weather drought and high fire risk times. The constant disturbance of mowing inhibits the growth of native plants by encouraging non-native weeds to grow. These weeds are detrimental to the natural habitat and landscape of our public parks and open spaces.

These native plants also support the health of our stormwater system. Allowing plants to grow without regular mowing promotes deeper root structure. Their roots help filter out pollutants and nutrients from stormwater run-off. Longer native grass also reduces erosion and allow water to seep into the soil. This recharges the groundwater and allows the water to slowly seep into the soil rather than flow quickly over the land, leaving soil dry.

Many staff hours and significant air emissions have gone into mowing in Westminster over the years. The EPA estimates that over five percent of total air pollution in urban areas comes from lawn mowers. Reducing the number of staff working on mowing operations on any given day during the summer frees up staff up to tackle additional projects in our parks and open space systems such as integrated pest management to reduce noxious weeds, trash collection, and more. Reducing the use of lawn mowers will also make our air cleaner and provide a healthier community for our families. Additionally, the constant running of lawn mowers and similar equipment contributes to noise pollution in our neighborhoods that will be significantly reduced under this new policy.

As mentioned above, mowing often promotes the growth of non-native plants. The City is required by law to eradicate certain noxious weeds within our public lands. While there are many ways to do so, chemical application is one that has proven effective but would be less necessary with a low mow policy. By limited mowing, the City also reduces the need for chemical herbicide application throughout our public lands. 

“Under normal fuel and wind conditions, Westminster Open Space and Westminster Fire Department are well positioned to contain and respond to wildland fires within the city. The threat of fire in the open spaces is largely mitigated by numerous natural and constructed fuel breaks as well as ongoing fuels management efforts. Easy access, robust water supply, and a well trained and equipped fire department support an effective response to wildland fire in our open space.”

-from the 2022 Open Space Fire Risk Assessment (p 42)