News & Press: Legislative/Regulatory News

Nursery Stock Cold Hardiness List Now Available and in Effect

Wednesday, November 8, 2017   (0 Comments)
Posted by: James Calkins, MNLA Regulatory Affairs Manager

The 2018 iteration of the Minnesota Department of Agriculture’s (MDA) Nursery Stock Cold Hardiness List is now available on the MDA website at Updated and published annually, the MDA Nursery Stock Cold Hardiness List serves as the legal authority for the labeling of nursery stock regarding cold hardiness in Minnesota. United States Department of Agriculture (USDA) Cold Hardiness Zones are used for the cold hardiness ratings (USDA Plant Hardiness Zone Map; and the list functions as the primary guidance utilized to identify false or misleading cold hardiness labeling for woody plants and herbaceous perennials offered for sale in the State of Minnesota. False or misleading labeling of nursery stock relative to cold hardiness is a violation of the Minnesota Nursery Law (Minnesota Statute 18H; and specifically Minnesota Statute 18H.14 (Labeling and Advertising of Nursery Stock;


As stated in the Minnesota Nursery Law:


(a) Plants, plant materials, or nursery stock must not be labeled or advertised with false or misleading information including, but not limited to, scientific name, variety, place of origin, and hardiness zone as defined by the United States Department of Agriculture, and growth habit.


(b) All nonhardy nursery stock as designated by the commissioner must be labeled correctly for hardiness or be labeled "nonhardy" in Minnesota.


The MDA Nursery Stock Cold Hardiness List divides nursery stock into eight primary categories with some overlap: Trees (deciduous and evergreen), Fruit (herbaceous and woody species), Fruit/Produce (asparagus and rhubarb), Grasses (landscape grasses), Perennials (herbaceous perennials), Roses, Shrubs (deciduous and evergreen, needle leaf and broadleaf), and Vines. According to the MDA, whenever nursery stock is labeled for cold hardiness, the hardiness rating on the label must be consistent with the cold hardiness rating published in the MDA Nursery Stock Cold Hardiness List. So long as the correct USDA plant cold hardiness rating is included on the label, nothing further is needed. Conversely, nursery stock that isn’t specifically labeled for cold hardiness and isn’t cold hardy in the area in which it is being sold must be labeled “nonhardy” to be in compliance with the Minnesota Nursery Law.


Note that cultivars are sometimes listed separately from the parent species when their cold hardiness has been documented as being different from the generally accepted cold hardiness level for the species based on credible evidence supporting the difference. For cultivars that are not specifically listed, nursery professionals and the public should refer to the species for the appropriate cold hardiness zone rating.


The MDA Nursery Stock Cold Hardiness List is reviewed and updated on an annual basis and multiple sources of information are considered during the review process. The Minnesota Nursery and Landscape Association (MNLA) has historically submitted comments as part of the annual review process and was pleased to have the opportunity to provide input once again this year. As in past years, the MNLA convened a review panel to review the draft MDA list in September and the group’s comments were submitted to the MDA for review and consideration by MDA staff. We thank the members of the MNLA review panel for sharing their time and expertise and note that many of the MNLA recommendations are reflected in the 2018 updated list. The current cold hardiness list will remain unchanged and effective until the list is reviewed and updated once again in September 2018.


The MDA Nursery Stock Cold Hardiness List impacts the MNLA membership from a regulatory perspective and MNLA members have a vested interest in assuring that the public has the best and most up-to-date cold hardiness information when purchasing landscape plants. For these reasons, the MNLA will remain engaged in the MDA’s cold hardiness assessment process. To this end, consensus among our members is important and we are interested in any comments you might have about the cold hardiness list and its implementation, and the annual review process in general, from a nursery and landscape perspective in preparation for next year’s review. We also encourage and would welcome additional participation from interested MNLA members during next year’s review of the MDA cold hardiness list; please let us know if you would be interested in serving on the MNLA review panel so we can add you to the list of reviewers for next year.


For additional information about cold hardiness labeling requirements for nursery stock, and questions about other nursery stock labeling requirements under the Minnesota Nursery Law, contact Steven Shimek (Minnesota Department of Agriculture, Plant Protection Division) at or (651) 201-6619. Additional information about the MDA Nursery Inspection & Certification Program, which is responsible for the administration of the Minnesota Nursery Law, including compliance with the law’s cold hardiness labeling requirements, is also available on the MDA website at


Note: In past years, a number of MNLA members have wondered whether the MDA Nursery Stock Cold Hardiness List is available in Excel spreadsheet form. While the MDA cannot post Excel documents on its website, the Excel spreadsheet can be obtained from the MNLA by contacting Jim Calkins at



To comment on the cold hardiness list, its implementation, and/or the annual plant cold hardiness review process with the goal of assisting the MNLA as it participates in future reviews, or to volunteer to serve on the MNLA plant cold hardiness review panel next year, contact Jim Calkins (MNLA Regulatory Affairs Manager) at or (952) 935-0682.

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