Invasive Plants

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Invasive Plant Outreach Materials Request Form

Background Information

Ch 273, Criteria for Listing Invasive Terrestrial Plants (DOC) describes the criteria a plant species must meet to be considered invasive and establishes three lists that regulate the sale of invasive plants in the horticulture trade.

The invasive plant lists described in Ch 273 are maintained by the Maine Department of Agriculture, Horticulture Program and include:

• Do Not Sell Invasive Plant List: The Do Not Sell List is also sometimes referred to as the Prohibited Plant List or the Banned Plant List. It is illegal to import, export, buy, sell or intentionally propagate for sale the species listed on the Do Not Sell Plant List.
• Watch List of Invasive Plants: Plants on the Watch List have been evaluated using the same criteria as the plants on the Do Not Sell List and while they meet some of the invasive plant criteria, the evidence is insufficient to add the plants to the Do Not Sell List at this time. The Watch List is intended to guide the evaluation process the next time the Invasive Plant Rule is reviewed. The plants on the Watch List may continue to be sold.
• Invasive Species of Special Concern: These species can be sold, but must have a sign or label indicating that the plants may be invasive in some habitats and alternative plants should be considered.

There are other invasive plant lists in Maine. While this may be confusing, each list serves a separate purpose. Invasive plant lists maintained by other programs and departments serve both regulatory and non-regulatory purposes.

• Advisory List of Invasive Plants: This list is maintained by the Maine Natural Areas Program in the Department of Agriculture, Conservation and Forestry. The Advisory List is NOT regulatory and is intended for education, outreach, land-management and other non-regulatory uses. Species on The Advisory List may be sold unless they are also listed on the Do Not Sell Plant List or the Invasive Aquatic Plant List.
• Invasive Aquatic Plant List: This list is maintained by the Invasive Aquatic Species Program in the Department of Environmental Protection. The Invasive Aquatic Plant List is a regulatory list of invasive aquatic plants that can not be introduced, propagated or sold in Maine.

Questions?: Call Gary Fish 207-287-7545 or email gary.fish@maine.gov

Do Not Sell Plant List

The invasive plants listed below are illegal to import, export, buy, sell or intentionally propagate for sale or distribution in Maine. The ban includes all cultivars, varieties and hybrids of these plants.

Printable Version (PDF 290KB)

Species on this list may no longer be sold after the effective date.

Report Do Not Sell List Plants Being Sold

Species links go to fact sheets that help with identifcation and control.

Invasive Species of Special Concern

These species may be sold, but require special labeling or signage.

Rosa rugosa is currently the only species in this category. Starting January 1, 2024 plant sellers will have to display these plants with either a label or a sign that meets the specifications in Chapter 273.

Sign specifications:

• Signs must be easily visible to shoppers
• Signs must be posted at 6 foot intervals around the block of plants
• Signs must be 8.5 inches wide by 11 inches tall
• Signs should be weather resistant and must be posted and readable as long as plants are offered for sale.
• Signs must have a light background with dark bold letters
• Lettering should be no smaller than 40 point Arial (or similar) font.
• Signs must include the words "Invasive Species - Harmful to the Environment" and "Ask about alternative plants" and "Follow species specific instructions provided by the vendor"

Example Signs: Example 1 (Landscape) Example 2 (Portrait)

The Horticulture Program has a number of signs, printed on weather resistant material, that are available upon request.

Label specifications:

• Each plant or container holding the plant must be labeled.
• Labels must be easily visible to shoppers.
• The label must contain the words "Invasive Species - Harmful to the Environment" in 14 point bold font.
• Labels must include non-invasive alternatives and provide instructions for preventing the spread of the labeled plant.
• Labels must be approved by the Department of Agriculture, Conservation and Forestry.

Example Labels: Example 1 (wrap tag) Example 2

Invasive Plant Watch List

The Watch List is intended to guide the evaluation process the next time the Invasive Plant Rule is reviewed. These plants were evaluated using the same criteria as the plants on the Do Not Sell list, but at the time of evaluation there was insufficient evidence to support adding these species to the Do Not Sell List.

Watch List plants may be sold with no restrictions.

Managing Invasive Plants for Horticultural Businesses

Weed Risk Assessment and Best Management Practices

Weeds and invasive plants compete with crops for water, nutrients, and sunlight. They may directly reduce profits by hindering harvest operations, lowering nursery stock quality, and producing chemicals that are harmful to other plants (allelopathy). One way to manage plants in horticultural businesses is to conduct a weed risk assessment to identify, apply and implement best management practices to manage weeds and invasive plants.

Conducting a Weed and Invasive Plant Risk Assessment (PDF), includes a list of general best management practices for managing invasive plants as well as specific best management practices for some of the plants on the Do Not Sell List.

Alternatives to Invasive Plants

• Gardening to Conserve Maine’s Native Landscape: Plants to Use and Plants to Avoid - University of Maine
• Plants for the Maine Landscape - University of Maine Master Gardener Manual
• Alternatives for Invasive Ornamental Plant Species (PDF) - Connecticut Agricultural Experiment Station
• Alternatives to Invasive Species (PDF) - Native Plant Trust
• Alternatives to Invasive Landscape Plants (PDF) - University of New Hampshire
• Native Plant Finder - National Wildlife Federation
• Plant Selection Resources - Maine YardScaping Partnership
• Maine Sources for Native Plants - Maine YardScaping Parnership
• Alternatives to Invasive or Potentially Invasive Exotic Species (PDF) - New England Wildflower Society

What are invasive plants?

The Invasive Plant rule lists specific criteria that a plant must meet in order to be considered invasive. The species must:

• be non-native,
• rapidly grow, establish and spread in minimally managed habitats,
• have the biological potential to spread widely including across spatial gaps (unassisted by people),
• exist in high numbers or large colonies in minimally managed habitats and
• displace native species in minimally managed habitats.

Updating the Do Not Sell Plant List

Chapter 273, Criteria for Listing Invasive Terrestrial Plants prescribes a five-year review of the species listed on the Do Not Sell Plant List. The last review of Chapter 273 was completed in 2022.

To review the list the Horticulture Program assembles a stakeholder committee comprised of a variety of individuals from industry, government, non-profit and educational institutions that represent different organizations affected by the development, implementation and enforcement of the prohibited plant list. With input from the stakeholder committee the Department evaluates species using the invasive plant criteria described in Chapter 273 and proposes changes to the Do Not Sell List.

Opportunities for Public Participation

In addition to the formal rule review that happens every 5 years, anyone can request review of a specific species at any time.

• To nominate a species for evaluation submit the Maine Invasive Species Nomination Form (PDF)
• To request an exemption for a new or existing cultivar of a species that is currently on the Do Not Sell List submit the Request to Exempt a Specific Cultivar and any supporting documentation.