Invasive plants regulated in New Hampshire (16 species, cited)

Invasive plants regulated in New Hampshire

New Hampshire regulates 16 invasive plants under N.H. Admin. Code Agr 3802.01. The table below reproduces that list in full, showing each plant's status in the state's own words. New Hampshire's list is a trade restriction, which governs what may be sold, propagated, or moved within the state.

Compiled from the rule itself, retrieved July 20, 2026. Law changes; if you spot a listing we have wrong or stale, tell us at [email protected].

Plant	Scientific name	Status	New Hampshire’s determination
Amur Honeysuckle	Lonicera maackii	Prohibited Invasive	New Hampshire lists Amur Honeysuckle under “NH prohibited invasive species.”Plant instead: Common Witch Hazel, Rhodora, Canadian Serviceberry
Asiatic Tearthumb	Polygonum perfoliatum	Prohibited Invasive	New Hampshire lists Asiatic Tearthumb under “NH prohibited invasive species.”
Black Alder	Alnus glutinosa	Prohibited Invasive	New Hampshire lists Black Alder under “NH prohibited invasive species.”Plant instead: Sweet Birch, Western Catalpa, Black Ash
Border Privet	Ligustrum obtusifolium	Prohibited Invasive	New Hampshire lists Border Privet under “NH prohibited invasive species.”Plant instead: New York Ironweed, Blue Huckleberry, Mountain Laurel
Broadleaved Pepperweed	Lepidium latifolium	Prohibited Invasive	New Hampshire lists Broadleaved Pepperweed under “NH prohibited invasive species.”
Burning Bush	Euonymus alatus	Prohibited Invasive	New Hampshire lists Burning Bush under “NH prohibited invasive species.”Plant instead: New York Ironweed, Hairy Lespedeza, American Black Elderberry
European Swallow-Wort	Cynanchum rossicum	Prohibited Invasive	New Hampshire lists European Swallow-Wort under “NH prohibited invasive species.”
Garlic Mustard	Alliaria petiolata	Prohibited Invasive	New Hampshire lists Garlic Mustard under “NH prohibited invasive species.”
Giant Knotweed	Polygonum sachalinense	Prohibited Invasive	New Hampshire lists Giant Knotweed under “NH prohibited invasive species.”
Japanese Honeysuckle	Lonicera japonica	Prohibited Invasive	New Hampshire lists Japanese Honeysuckle under “NH prohibited invasive species.”Plant instead: Roundleaf Goldenrod, New York Ironweed, Roadside Agrimony
Japanese Knotweed	Fallopia japonica (potentially invasive weed)	Prohibited Invasive	New Hampshire lists Japanese Knotweed under “NH prohibited invasive species.”
Kudzu	Pueraria montana	Prohibited Invasive	New Hampshire lists Kudzu under “NH prohibited invasive species.”Plant instead: American Plum, Chokecherry, Red-Barked Dogwood
Louise's Swallow-Wort	Cynanchum louiseae	Prohibited Invasive	New Hampshire lists Louise's Swallow-Wort under “NH prohibited invasive species.”
Nepalese Browntop	Microstegium vimineum	Prohibited Invasive	New Hampshire lists Nepalese Browntop under “NH prohibited invasive species.”
Tree of Heaven	Ailanthus altissima	Prohibited Invasive	New Hampshire lists Tree of Heaven under “NH prohibited invasive species.”Plant instead: Sweet Birch, Western Catalpa, Black Ash
Variegated Water Grass	Glyceria maxima 'Variegata'	Prohibited Invasive	New Hampshire lists Variegated Water Grass under “NH prohibited invasive species.”Plant instead: Common Rush, Big Bluestem, Yellow Indian Grass

What the tags mean

Prohibited Restricted Listed

A legal status. New Hampshire names the plant in statute. Under a nursery rule that means it may not be sold, propagated, or moved; under an agricultural weed law it means landowners must control it. The cited rule says which, in New Hampshire’s own words, in the last column.

Invasive

An ecological finding, and a different question from the law. GRIIS — the Global Register of Introduced and Invasive Species — lists the plant as invasive in the United States. Most invasive plants carry no state listing at all and are sold freely, so a plant without this tag is not thereby safe, and a plant without a legal chip is not thereby harmless.

Where this comes from

New Hampshire listings: N.H. Admin. Code Agr 3802.01. Read the rule.
Invasive status: GRIIS, the Global Register of Introduced and Invasive Species, via GBIF. A scientific register with no legal force; it is cited separately from the statute above because the two disagree far more often than they agree.
Status wording: Each determination is written as a sentence, with New Hampshire’s own term for the plant reproduced verbatim inside it. The Prohibited / Restricted / Listed chips are Ezina’s normalisation across 42 states and are not the legal term.
Nativity: USDA PLANTS county distribution layer, surfaced through the county checker.

Regulated next door, but not in New Hampshire

Plants that two or more states bordering New Hampshire regulate, and New Hampshire does not. A listing is a legal act rather than an ecological one, so a plant can be a documented problem here and still be sold here.

Bishop's Goutweed Aegopodium podagraria regulated in Maine, Massachusetts, Vermont
Common Barberry Berberis vulgaris regulated in Maine, Massachusetts, Vermont
Common Reed Phragmites australis regulated in Maine, Massachusetts, Vermont
Flowering Rush Butomus umbellatus regulated in Maine, Massachusetts, Vermont
Glossy Buckthorn Frangula alnus regulated in Maine, Massachusetts, Vermont
Japanese Barberry Berberis thunbergii regulated in Maine, Massachusetts, Vermont
Morrow's Honeysuckle Lonicera morrowii regulated in Maine, Massachusetts, Vermont
Norway Maple Acer platanoides regulated in Maine, Massachusetts, Vermont
Oriental Bittersweet Celastrus orbiculatus regulated in Maine, Massachusetts, Vermont
Paleyellow Iris Iris pseudacorus regulated in Maine, Massachusetts, Vermont
Purple Loosestrife Lythrum salicaria regulated in Maine, Massachusetts, Vermont
Tatarian Honeysuckle Lonicera tatarica regulated in Maine, Massachusetts, Vermont
Amur Corktree Phellodendron amurense regulated in Maine, Massachusetts
Amur Maple Acer ginnala regulated in Maine, Vermont
Amur Silvergrass Miscanthus sacchariflorus regulated in Maine, Massachusetts

Questions

What plants are illegal to sell in New Hampshire?

16 plants are regulated under N.H. Admin. Code Agr 3802.01. Plants marked Prohibited may not be sold, propagated, or moved within New Hampshire. Plants marked Restricted carry narrower limits set by the rule.

Is my plant invasive in New Hampshire?

Search the table on this page, or enter the plant's name in Ezina's checker to get its New Hampshire status alongside whether USDA records it as native to your specific county. Every answer links the record it came from.

Does a plant missing from this list mean it is safe to plant in New Hampshire?

No. This page reproduces what New Hampshire regulates, and a state list is a legal instrument rather than an ecological verdict. Plenty of plants spread aggressively without ever being listed, and states add species years after the problem is documented.

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