Sun Prairie, WI Landscaping Rules: Weed Ordinances (2026)

010 requires every property owner, occupant or agent in charge of a lot to destroy noxious weeds before they reach the bloom or flower stage, and separately caps the height of noxious weeds, grasses and lawns at eight inches from the ground surface anywhere within the city corporate limits. The city clerk must publish an annual notice by May 15th reminding owners of the duty. The ordinance names specific noxious weeds by species, including Canada thistle, common and great ragweed, leafy spurge, wild parsnip, poison ivy and hemp, plus noxious grasses such as redtop, orchard grass, timothy, Johnson grass and foxtail.

Growth over eight inches is declared a public nuisance under subsection C, with limited exceptions for floodplain, wetland, stormwater facility and undeveloped park land. The building inspector serves as the city's weed commissioner and, once weeds are found in violation, must serve notice demanding abatement within five calendar days. If the owner does not comply, the enforcement officer can abate the nuisance directly and charge the cost back to the property owner, plus a flat twenty-five dollar administrative fee assessed regardless of whether the owner ultimately abates it themselves.

Unpaid bills, if not paid within ten calendar days of billing, get placed on the property's tax roll as a special tax within sixty days. Nonresidential vacant parcels carry an added mowing duty: the terrace and up to fifteen feet behind the right-of-way must be kept under eight inches, and vacant parcels next to a public park or an improved property must be mowed within fifteen feet of that shared line, though the mowing rule does not reach agricultural crops.