N.H. Rev. Stat. § 433:7-a
Administration and enforcement of this subdivision shall be implemented in an equitable manner throughout the state. This subdivision is of statewide concern and occupies the whole field of regulation regarding the display, distribution, growing, cultivation, harvesting, production, labeling, marketing, mixing, notification of use, planting, possession, processing, registration, sale, storage, transportation, or other use; or the inspection, analysis, examination, certification, classification, testing, or licensing of agricultural, flower tree, shrub, or vegetable seeds, or products or sellers of such seeds to the exclusion of all local regulation. Except as otherwise specifically provided in this subdivision, no ordinance or regulation of local government, including but not limited to, an action by a local governmental agency or department, a county board of commissioners or a city council, or a local regulation adopted by the use of an initiative measure, may prohibit or in any way attempt to regulate any matter relating to the display, distribution, growing, cultivation, harvesting, production labeling, marketing, mixing, notification of use, planting, possession, processing, registration, sale, storage, transportation, or other use, or the inspection, analysis, examination, certification, classification, testing, licensing, of agricultural, flower tree, shrub, or vegetable seeds or products or sellers of such seeds and any of those ordinances, laws, or regulations are void and of no force or effect. Nothing in this subdivision shall limit the authority of any political subdivision to adopt and enforce planning, zoning and related regulations under RSA 674, including the authority to require native plantings, and combat invasive species listed in accordance with RSA 430:53 as part of a planning board's site plan review or subdivision authority or as a condition of a zoning board of adjustment's granting of a variance or special exception.
RSA 433:7-a
2018, 169:1, eff. Aug. 7, 2018.