Canada: Province & Territories Plant Regulations

A spreadsheet of 238 plants regulated across Canada and an additional 320 plants regulated in the 13 U.S. States that border Canada (as of July 13, 2023) has been uploaded (it will download when clicked). The spreadsheet may contain errors, but links to the original regulatory sources are provided below and on the USA: Border States Plant Regulations page. It is important to note that these regulated species represent only a portion of the plants known to pose high risks through the horticultural trade. Most plants that are regulated today are classified as noxious weeds, with a primary focus on agricultural impacts.

*Aquatic invasive plants are especially challenging because they are not defined or regulated consistently. Some invasive plant lists use a narrow definition of “aquatic,” covering plants that only live in water, such as watermilfoil (Myriophyllum spicatum). Other lists take a broader view and include wetland and shoreline plants that can affect lakes, rivers, and wetlands, such as purple loosestrife (Lythrum salicaria). This lack of clarity makes regulations harder to align and leaves important species unaddressed.

Summary of Regulations: Links 1 – 14 jump to more information below.

  1. Canada:
    • Prohibits 21 plant taxa and restricts for others under the Plant Protection Act (SC 1990, c. 22);
    • Regulates 96 Noxious Weeds under the Seeds Act (R.S.C., 1985, c. S-8)
    • No aquatic plants are regulated at the Federal level.
  2. Alberta:
  3. British Columbia:
    • Regulates 66 Noxious Weeds under the Weed Control Act (RSBC, 1996, c. 487);
    • Regions may regulate approximately 30 more taxa according to Spheres of Concurrent Jurisdiction – Environment and Wildlife Regulation (BC Reg 144/2004) Environmental Management Act (SBC 2003, c 53)
    • 9 aquatic plants appear in legislation
  4. Manitoba
  5. New Brunswick
    • Currently no plants are explicitly regulated under the Weed Control Act (SNB 1969, C.21)
  6. Newfoundland and Labrador
    • No regulated plant lists
  7. Northwest territories
    • No regulated plant lists
  8. Nova Scotia
    • 10 Noxious Weeds are regulated under the Agricultural Weed Control Act (R.S.N.S. 1989, c. 501)
    • No regulated aquatic plants
  9. Nunavut
    • No regulated plant lists
  10. Ontario
    • Regulates 25 Noxious Weeds under the Weed Control Act (R.S.O. 1990, c. W.5) 
    • Prohibits or restricts 22 Invasive plant taxa under the Invasive Species Act (S.O. 2015, c.22)
    • Regulates 14-19 aquatic plants* under the Invasive Species Act (S.O. 2015, c.22)
  11. Prince Edward Island
    • Regulates 1 plant taxa under the Purple Loosestrife Control Regulations, Weed Control Act, RSPEI 1988, c W-2Agricultural Weed Control Act (R.S.N.S. 1989, c. 501)
  12. Quebec
    • Québec has announced its intention to prohibit 31 plants (Oct, 2025)
    • 11 – 16 aquatic taxa* are proposed within pending legislation
  13. Saskatchewan
    • Regulates 60 Noxious Weeds under the Weed Control Act (Chapter W-11.1 2014, c.19)
    • 6 aquatic plants are among the regulated noxious weeds
  14. Yukon
    • No regulated plant lists

Canada

Regulatory approach

Canada regulates invasive and noxious plants through two primary federal statutes, each with a narrow and distinct purpose, rather than through a unified invasive plant framework:

Responsibility for administering both Acts rests with the Canadian Food Inspection Agency (CFIA).

The Plant Protection Act is intended “to protect plant life and the agricultural and forestry sectors” and focuses on plant pests and diseases, not biodiversity impacts.
The Seeds Act is designed to ensure seed quality and purity for agricultural production, including limits on weed seed contamination.

Neither statute was designed as a comprehensive invasive species prevention tool.

Interaction with fisheries legislation

In 2015, the Fisheries Act ( R.S.C. , 1985, c. F-14) was amended to include the  Aquatic Invasive Species Regulations (SOR/2015-121).

  • These regulations establish prohibitions and controls for aquatic invasive species, primarily animals.
  • No aquatic plant species are listed in the Species Subject to Prohibitions and Controls schedules.

At the time of enactment, plants were excluded on the basis that CFIA was considered to have authority over plants, including aquatic plants.

However, CFIA does not currently treat aquatic invasive plants as within its operational mandate, creating a regulatory gap between plant-health legislation and fisheries legislation.

Current CFIA policy position:

  • CFIA primarily regulates plants not present in Canada, or if plants that occur in Canada under narrow plant-health or pest-host circumstances.
  • Prevention of invasive plants already in trade is largely treated as a regional or provincial responsibility, rather than a federal one.

Notably:

CFIA has since removed or declined to maintain federal prohibitions on aquatic invasive plants, despite evidence of ecological risk. (See for example CFIA, Weed Risk Assessment Trapa natans, 2001).

What is regulated:

🌱25 plant taxa are regulated under the PPA. CFIA, Invasive Plants, 2025

  • 21 are regulated under Directive D-12-01, and a further
  • 4 woody taxa (barberry related species and buckthorns) are regulated under Directive D-01-04 because they serve as alternate hosts for economically important cereal rust diseases.

💧 One Aquatic Invasive Plant* is included with the 21 regulated under Directive D-12-01

  • *Giant reed (Arundo donax) can significantly impact wetlands and riparian areas, although it is not a strictly aquatic plant.

⚠️ Important clarification:
These directives regulate plants based on plant health and disease risk, not impacts on biodiversity, waterways, or public health.

Federal regulatory action is focused primarily on plants not yet present in Canada, or on a small number of species regulated for specific plant-health reasons. Aquatic invasive plants are not explicitly included. Once plants are widely present or reported as escaping cultivation, responsibility for management and prevention is largely devolved to provinces and territories

🌱96 Noxious Weeds are regulated under the Weed Seeds Order

  • 26 Class 1 Prohibited noxious weeds
  • 36 Class 2 Primary noxious weeds
  • 29 Class 3 Secondary noxious weeds
  • 5 Class 4 Secondary noxious weeds
  • 42 Class 5   

Schedule 1 of the Seeds Regulations (C.R.C., c. 1400) prescribe the number of weed seeds from various classes allowed per kg as contaminants in various seed products.

⚠️ Scope limitation:
The Weed Seeds Order regulates seed as a contaminant of products.

💧 2 Aquatic Invasive Plants* are included under the Weed Seeds Order

  • *Purple loosestrife (Lythrum salicaria) and Giant hogweed (Heracleum mantegazzianum) can significantly impact wetlands and riparian areas, although they are not a strictly aquatic plants.

Key limitations

  • Responsibility for regulating plant sales is largely devolved to provinces and territories, creating uneven protection.
  • There is no centralized federal authority responsible for preventing the spread of invasive plants across pathways.
  • Current CFIA policy does not adequately prevent the sale of invasive plants, particularly in the horticultural and aquarium trades.
  • Authority over aquatic invasive plants is ambiguous, split between fisheries and plant-health frameworks that exclude them in practice.
  • Federal legislative tools prioritize food security and plant health, not biodiversity protection, functioning aquatic systems, or public health.

Associated Policy, Legislation and Agreements (context-setting, not regulatory instruments)

Learn more

  • Invasive Alien Species Task Force (2017) Recommendations to Improve IAS Prevention and Management (pdf)
  • Reports of the Commissioner of the Environment and Sustainable Development to the Parliament of Canada, (2019) Aquatic Invasive Species
  • Azan, S., Invasive aquatic plants and the aquarium and ornamental pond industries (2011)
    Gantz, Mandrak, & Keller, Application of an Aquatic Plant Risk Assessment to Non-Indigenous Freshwater Plants in Trade in Canada. DFO (2014)
  • Gordon, D., at al., Weed Risk Assessment for Aquatic Plants (2012)
  • Marson, et al. Summary of a survey of aquarium owners in Canada (2009)
  • Marson,et al.  Summary of a survey of water garden owners in Canada (2009)

Alberta

Regulatory approach

Alberta has a Weed Control Act (SA 2008, c.W-5.1) and the associate Weed Control Regulation (19/2010) regulating plants that pose significant economic, social or ecological risks. In addition, invasive aquatic plant movement is managed under the Fisheries (Alberta) Act (RSA 2000, c F-16).

What is regulated

🌱 73 terrestrial plants Provincially Regulated Weeds
44 prohibited noxious weeds; 29 noxious weeds (eradication or control required once listed)

💧 11 species aquatic invasive plants* are included among the Provincially Regulated Weeds

  • *Butomus umbellatus (flowering rush), Fallopia × bohemica (hybrid or Bohemian knotweed), Fallopia japonica (Japanese knotweed), Fallopia sachalinensis (giant knotweed), Heracleum mantegazzianum (giant hogweed), Impatiens glandulifera (Himalayan balsam), Iris pseudacorus (yellow flag iris), Lythrum salicaria (purple loosestrife), Myriophyllum spicatum (Eurasian watermilfoil), Tamarix chinensis (saltcedar or tamarisk), and Tamarix ramosissima (saltcedar or tamarisk).
  • Knotweed listed in genus Fallopia rather than currently accepted Reynoutria

💧 16 aquatic invasive plants Aquatic Invasive Species under the Fisheries Act

  • Brazilian elodea (Egeria densa), curly-leaf pondweed (Potamogeton crispus), Eurasian watermilfoil (Myriophyllum spicatum), European frog-bit (Hydrocharis morsus-ranae), European water chestnut (Trapa natans), fanwort (Cabomba caroliniana), flowering rush (Butomus umbellatus), giant salvinia (Salvinia molesta), Himalayan balsam (Impatiens glandulifera), hydrilla (Hydrilla verticillata), phragmites or common reed (Phragmites australis subsp. australis), purple loosestrife (Lythrum salicaria), variable-leaf watermilfoil (Myriophyllum heterophyllum), water soldier (Stratiotes aloides), yellow flag iris (Iris pseudacorus), and yellow floating-heart (Nymphoides peltata).
  • 5 species: Butomus umbellatus (flowering rush), Myriophyllum spicatum (Eurasian watermilfoil), Yellow flag iris (Iris pseudacorus), Purple loosestrife (Lythrum salicaria) and Phragmites (Phragmites australis subsp. australis) also also appear in the Weed Control Regulation.
  • Regulated under fisheries legislation (possession, transport, and release prohibited under fisheries legislation)

Key limitations

  • Aquatic plants are regulated inconsistently with duplications and gaps
  • Taxonomic ambiguity and hybrid species complicate enforcement
    • The knotweeds are one example of plants for which there is considerable taxonomic confusion and hybridization can make this complicated. Different provinces are using different nomenclature and some provinces seem unaware of hybrids.
  • Limited publicly accessible information on distribution and impacts

British Columbia

Regulatory approach

Provincial weed legislation combined with regional authority to regulate additional specie:, Weed Control Act (RSBC 1996, C. 487); Weed Control Regulation (BC Reg 66/85); Spheres of Concurrent Jurisdiction – Environment and Wildlife Regulation (B.C. Reg. 144/2004).

What is regulated

🌱 39 species regulated province-wide; 27 additional species regulated at the regional level under Weed Control Regulation

  • Provincially regulated: velvetleaf (Abutilon theophrasti), jointed goatgrass (Aegilops cylindrica), garlic mustard (Alliaria petiolata), bur chervil (Anthriscus caucalis), wild oats (Avena fatua), flowering rush (Butomus umbellatus), diffuse knapweed (Centaurea diffusa), spotted knapweed (Centaurea maculosa), yellow starthistle (Centaurea solstitialis), rush skeletonweed (Chondrilla juncea), Canada thistle (Cirsium arvense), common crupina (Crupina vulgaris), dodder (Cuscuta spp.), yellow nutsedge (Cyperus esculentus), purple nutsedge (Cyperus rotundus), hound’s-tongue (Cynoglossum officinale), leafy spurge (Euphorbia esula), bohemian knotweed (Fallopia × bohemica), Japanese knotweed (Fallopia japonica), giant knotweed (Fallopia sachalinensis), giant mannagrass or reed sweetgrass (Glyceria maxima), giant hogweed (Heracleum mantegazzianum), yellow flag iris (Iris pseudacorus), dalmatian toadflax (Linaria dalmatica), common toadflax (Linaria vulgaris), purple loosestrife (Lythrum salicaria), scentless chamomile (Matricaria maritima), Himalayan knotweed (Polygonum polystachyum), common reed (Phragmites australis subsp. australis), tansy ragwort (Senecio jacobaea), milk thistle (Silybum marianum), perennial sow thistle (Sonchus arvensis), annual sow thistle (Sonchus oleraceus), smooth cordgrass (Spartina alterniflora), English cordgrass (Spartina anglica), dense-flowered cordgrass (Spartina densiflora), saltmeadow cordgrass (Spartina patens), gorse (Ulex europaeus), and North Africa grass (Ventenata dubia).
  • Regionally regulated: Russian knapweed (Acroptilon repens), quackgrass (Agropyron repens), common bugloss (Anchusa officinalis), wild chervil (Anthriscus sylvestris), burdock (Arctium spp.), hoary alyssum (Berteroa incana), hoary cress (Cardaria spp.), plumeless thistle (Carduus acanthoides), meadow knapweed (Centaurea pratensis), oxeye daisy (Chrysanthemum leucanthemum), marsh plume thistle (Cirsium palustre), blueweed (Echium vulgare), Tartary buckwheat (Fagopyrum tataricum), cleavers (Galium aparine), orange hawkweed (Hieracium aurantiacum), field scabious (Knautia arvensis), kochia (Kochia scoparia), perennial pepperweed (Lepidium latifolium), white cockle (Lychnis alba), Scotch thistle (Onopordum acanthium), sulphur cinquefoil (Potentilla recta), Russian thistle (Salsola kali), green foxtail (Setaria viridis), night-flowering catchfly (Silene noctiflora), wild mustard (Sinapis arvensis), common tansy (Tanacetum vulgare), and puncturevine (Tribulus terrestris).
  • Knotweeds are listed under Fallopia rather than Reynoutria
  • Spartina patens should be Sporobolus pumilus; Spartina alterniflora should be Sporobolus alterniflorus

💧 10 aquatic/semiaquatic invasive plants are included under the Weed Control Act

  • Provincial: bohemian knotweed (Fallopia × bohemica), common reed (Phragmites australis subsp. australis), flowering rush (Butomus umbellatus), giant hogweed (Heracleum mantegazzianum), giant knotweed (Fallopia sachalinensis), Japanese knotweed (Fallopia japonica), purple loosestrife (Lythrum salicaria), saltmeadow cordgrass (Spartina patens), and smooth cordgrass (Spartina alterniflora).
  • Regional: marsh plume thistle (Cirsium palustre)

🌱 ~43 plant terrestrial plant taxa appear in Spheres of Concurrent Jurisdiction

  • The following plants are listed under the headings Plants and Terrestrial Plants: velvetleaf (Abutilon theophrasti), jointed goatgrass (Aegilops cylindrica), garlic mustard (Alliaria petiolata), wild oats (Avena fatua), smooth brome grass (Bromus inermis), downy brome grass (Bromus tectorum), nodding thistle (Carduus nutans), diffuse knapweed (Centaurea diffusa), spotted knapweed (Centaurea maculosa), yellow starthistle (Centaurea solstitialis), rush skeletonweed (Chondrilla juncea), Canada thistle (Cirsium arvense), bull thistle (Cirsium vulgare), poison hemlock (Conium maculatum), common crupina (Crupina vulgaris), dodder (Cuscuta spp.), hound’s-tongue (Cynoglossum officinale), Scotch broom (Cytisus scoparius), yellow nutsedge (Cyperus esculentus), purple nutsedge (Cyperus rotundus), orchard grass (coast) (Dactylis glomerata), spurge laurel (Daphne laureola), common barnyard grass (Echinochloa crus-galli), leafy spurge (Euphorbia esula), baby’s breath (Gypsophila paniculata), English ivy (Hedera helix), giant hogweed (Heracleum mantegazzianum), St. John’s wort (Hypericum perforatum), Himalayan balsam (Impatiens glandulifera), dalmatian toadflax (Linaria dalmatica), common toadflax (Linaria vulgaris), scentless chamomile (Matricaria maritima), kudzu (Pueraria montana), Japanese knotweed (Reynoutria japonica), giant knotweed (Reynoutria sachalinensis), Himalayan blackberry (Rubus armeniacus), tansy ragwort (Senecio jacobaea), carpet burweed (Soliva sessilis), perennial sow thistle (Sonchus arvensis), annual sow thistle (Sonchus oleraceus), saltcedar (Tamarix spp.), yellow salsify (Tragopogon dubius), and gorse (Ulex europaeus).
  • There are some duplications like dodder and common cuprina; giant knotweed is oddly listed twice

💧 8 – 16 aquatic/semiaquatic invasive plants are included under Spheres of Concurrent Jurisdiction

  • Listed as Fresh Water/Riparian Vascular Plants (common names only in law): flowering rush (Butomus umbellatus), hydrilla (Hydrilla verticillata), yellow flag (Iris pseudacorus), purple loosestrife (Lythrum salicaria), Eurasian watermilfoil (Myriophyllum spicatum), reed canary grass (Phalaris arundinacea), common reed (Phragmites australis subsp. australis), and curly pondweed (Potamogeton crispus).
  • Additional invasive plants impacting aquatic systems: bohemian knotweed (Fallopia × bohemica), giant knotweed (Fallopia sachalinensis), Japanese knotweed (Fallopia japonica), giant hogweed (Heracleum mantegazzianum), Himalayan balsam (Impatiens glandulifera), purple loosestrife (Lythrum salicaria), saltmeadow cordgrass (Spartina patens), and smooth cordgrass (Spartina alterniflora).

Key limitations

  • Regionalized authority results in uneven regulation and confusion across the province
  • Common-name listings in Spheres of Concurrent Jurisdiction create confusion, taxonomic ambiguity and enforcement challenges
    • Purple loosestrife may refer to Lythrum salicaria or more broadly to Lythrum species and hybrids including with L. virgatum & L. alatum.
    • Reed canary grass (Phalaris arundinacea) includes native and introduced genotypes
    • Saltcedar is a collective common name covering multiple Tamarix species
    • Knotweed used generically, but covers several genera in the family Polygonaceae including: Fallopia, Persicaria, Polygonum, Reynoutria

Additional information

Manitoba

Regulatory approach
Tiered weed legislation for plants under the Noxious Weeds Act (S.M. 2015, c.38), combined with a strong aquatic invasive species regime under Water Protection Act – Aquatic Invasive Species Regulation (C.C.S.M. c. W65).

What is regulated

🌱 89 invasive plants are specified in the Declaration Of Noxious Weeds

  • 21 Tier 1 (eradication required)
  • 18 Tier 2 (restricted)
  • 50 Tier 3 (complaint-controlled)

💧 3 aquatic invasive plants* are included in the Declaration Of Noxious Weeds

  • *Knotweed, Japanese (Fallopia japonica), Purple loosestrife (Lythrum salicaria), Common reed (Phragmites australis subsp. australis), Saltcedar (Tamarix ramosissima) – although not strictly aquatic plants.

💧 21 aquatic invasive plant taxa (includes groups of species) are regulated under the Aquatic Invasive Species Regulation

  • Brazilian elodea (Egeria densa), common reed (Phragmites australis subsp. australis), curly-leaf pondweed (Potamogeton crispus), Eurasian watermilfoil (Myriophyllum spicatum), European frogbit (Hydrocharis morsus-ranae), fanwort (Cabomba caroliniana), flowering rush (Butomus umbellatus), Himalayan balsam (Impatiens glandulifera), hydrilla (Hydrilla verticillata), oxygen weed (Lagarosiphon major), parrot’s feather (Myriophyllum aquaticum), purple loosestrife (Lythrum salicaria, including all cultivars, varieties, and hybrids), saltcedars or tamarisks (Tamarix ramosissima, T. chinensis, and T. parviflora, including all cultivars, varieties, and hybrids), slender naiad (Najas minor), starry stonewort (Nitellopsis obtusa), water chestnut (Trapa natans), water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), water soldier (Stratiotes aloides), yellow flag iris (Iris pseudacorus), and yellow floating-heart (Nymphoides peltata). (Riparian species in bold – note inclusion on hybrids and cultivars)
  • Possession prohibited, effectively restricting transport and distribution

Key limitations

  • Terrestrial invasive plant regulation remains agriculture-focused
  • Only one knotweed species listed, despite widespread hybridization. Knotweed listed in genus Fallopia rather than currently accepted Reynoutria
  • Separate statutes govern terrestrial and aquatic invasive plants, limiting coordination

New Brunswick (NB)

Regulatory approach

The NB Weed Control Act (SNB 1969, C.21) provides general authority to manage noxious weeds, but it does not currently list any plant species by name for regulation. No separate provincial statute specifically designates terrestrial or aquatic invasive plant species by taxon.

What is regulated

🌱 No terrestrial invasive plant species are regulated by name under provincial statute or regulation

💧 No aquatic invasive plants are explicitly prohibited

Key limitations

  • There is no provincial regulatory instrument that specifically lists or prohibits invasive plant species by name

Additional Information

New Brunswick Council of Invasive Species (NBCIS); 📌 Call for Action to the Federal Committee on Fisheries and Oceans (2019)

Newfoundland and Labrador

Regulatory approach

Newfoundland and Labrador does not currently have provincial legislation that lists prohibited or regulated invasive plant species by name, nor regulations that explicitly prohibit the release of invasive plants into the wild.

What is regulated

🌱 No terrestrial invasive plant species are regulated by name under provincial statute or regulation.

💧No aquatic invasive plants are explicitly prohibited

Key limitations

  • No species-specific regulatory instruments for invasive plants
  • Invasive plant management is fragmented across statutes not written with invasive alien species (IAS) as their primary focus
  • Regulatory tools remain largely reactive and discretionary

Additional information

Newfoundland and Labrador hosted the Exotic and Invasive Alien Species Workshop (2008), which included a review of provincial and federal legislation. Key findings at the time included:

  • Most relevant legislation was written before invasive alien species were recognized as a major ecological issue
  • Many Acts address substances or organisms indirectly, and could be interpreted to apply to IAS, but were not designed for that purpose
  • Legislation often focuses on industry protection or human health (e.g., Plant Protection Acts), rather than ecosystem integrity
  • Significant gaps in regulation, knowledge, definitions, and resources were identified
  • A need for improved inter-agency cooperation and legislative modernization was emphasized

Nova Scotia

Regulatory approach

Agriculture-focused weed legislation that designates a short list of “noxious weeds” under regulations Agricultural Weed Control Act, (RSNS 1989, c 501) Nova Scotia Legislature and Weed Control Regulations, (NS Reg 57/68 as amended)

What is regulated

🌱 10 noxious weed species entries in Schedule “A” of the Weed Control Regulations

Class Number One (9 species) — described as capable of spreading to cultivated or pasture lands, including: common milkweed (Asclepias syriaca) (native), wild chervil (Anthriscus sylvestris), velvetleaf (Abutilon theophrasti), field bindweed (Convolvulus arvensis), yellow nut sedge (Cyperus esculentus), leafy spurge (Euphorbia esula), white cockle (Lychnis alba), tansy ragwort (Senecio jacobaea) (area-limited), marsh hedge nettle (Stachys palustris)

Class Number Two (1 taxa) — described as capable of inflicting economic loss or ill health: thorn-apple (Datura spp.)

💧 One aquatic invasive plant* is included in the noxious weed list

  • Hedge nettle (Stachys palustris)

Key limitations

  • The framework is land-use/agriculture oriented (spread into cultivated/pasture lands; economic loss/ill health) rather than designed around broader invasive impacts on natural ecosystems.
  • Very limited species coverage (10 listed entries). 
  • The list includes at least one native species (common milkweed), underscoring that this is a weed-control regime, not an invasive-species regime.

Additional information

Halifax has produced an “Invasive Species Watchlist” (useful for awareness and reporting), but it provides guidance, not regulation.

Northwest Territories

Regulatory approach

No territorial statute or regulation appears to list prohibited invasive plants by species. The territorial legal tool most relevant to biodiversity protection is the Protected Areas Act (SNWT 2019, c. 11). It may be possible through this act to undertake protective measures.

What is regulated

🌱 No terrestrial invasive plant species are regulated by name under provincial statute or regulation

💧 No aquatic invasive plants are explicitly prohibited

Key limitations

  • No species-specific regulatory instruments for invasive plants

Additional information

Nunavut

Nunavut does not regulate invasive plants through species-specific lists; however, the Wildlife Act (S.Nu. 2020, c.15)  establishes a strong preventive framework by prohibiting the release of species into habitats where they do not naturally occur.

What is regulated

🌱 No formal list of prohibited or regulated invasive plant species exists under Nunavut legislation.

Key limitations

  • No species-specific invasive plant lists or prohibitions exist.
  • Regulation relies on general release prohibitions, not targeted plant trade or sale controls.
  • Surveillance and reporting capacity remain limited due to geography and resources.
  • Increasing climate suitability raises the risk of future establishment of invasive plants.

Additional information

Ontario

Ontario uses two parallel legislative frameworks to regulate plants. Under the Weed Control Act  (R.S.O. 1990, c. W.5), Ontario designates noxious weeds through Regulation 1096. This regulation lists 25 species that landowners and municipalities are responsible for controlling to protect agricultural and horticultural lands. In addition, Ontario has an explicit Invasive Species Act, (S.O. 2015, c.22) with associated list of Invasive Species to Which the Act Applies (O. Reg. 354/16) focuses on preventing environmental harm.  It specifically has provisions to regulate both terrestrial and aquatic plant species harming or likely to harm the natural environment.

What is regulated

🌱 25 noxious weed species listed in Regulation 1096 require control

💧 One regulated aquatic invasive plant* is included in Regulation 1096

  • Giant hogweed (Heracleum mantegazzianum) – not strictly aquatic but impacts wetlands

🌱 8 regulated terrestrial invasive taxa listed O. Reg. 354/16

  • Black dog-strangling vine (Cynanchum louiseae), dog-strangling vine (Cynanchum rossicum), Bohemian knotweed (Reynoutria × bohemica), giant knotweed (Reynoutria sachalinensis), Japanese knotweed (Reynoutria japonica), Himalayan knotweed (Koenigia polystachya), common reed or phragmites (Phragmites australis subsp. australis), and tree-of-heaven (Ailanthus altissima)

💧 14 -19 regulated aquatic invasive plant taxa* listed O. Reg. 354/16

  • Water ferns (all species in the genus Azolla), flowering rush (Butomus umbellatus), Brazilian elodea (Egeria densa), European frog-bit (Hydrocharis morsus-ranae), Carolina fanwort (Cabomba caroliniana), European water chestnut (Trapa natans), Hydrilla (Hydrilla verticillata), oxygen weed (Lagarosiphon major),  floating primrose-willow (Ludwigia peploides), parrot feather (Myriophyllum aquaticum), Eurasian water-milfoil (Myriophyllum spicatum), yellow floating-heart (Nymphoides peltata), water soldier (Stratiotes aloides), watermoss (All species in the genus Salvinia)
  • Bohemian knotweed (Reynoutria × bohemica), giant knotweed (Reynoutria sachalinensis), Japanese knotweed (Reynoutria japonica), Himalayan knotweed (Koenigia polystachya), common reed or phragmites (Phragmites australissubsp. australis) may be considered threats to aquatic systems

Key limitations

  • Despite having a dedicated invasive species statute, relatively few plant species are regulated, particularly terrestrial invasive plants.
  • Regulation is stronger for aquatic plants than for terrestrial plants.
  • Parallel statutes (Invasive Species Act vs. Weed Control Act) create fragmentation between environmental and agricultural objectives.

Additional information

Prince Edward Island

Regulatory approach

Prince Edward Island regulates plants through its Weed Control Act (RSPEI 1988, c W-2.1). The Act authorizes the Lieutenant Governor in Council to designate as a noxious weed any plant that adversely affects or is likely to adversely affect any person, crop, desirable plant, animal, or property. Only explicit Purple Loosestrife Control Regulations (2004) are in place.

What is regulated

🌱 One terrestrial invasive plant taxon (Lythrum species)

💧 One aquatic invasive plant taxon (Lythrum species)

Key limitations

  • The regulatory focus reflects agricultural and property impacts, rather than environmental impacts.
  • Currently, application is extremely narrow.
  • Reliance on education and voluntary compliance rather than broad regulatory prevention.
  • No pathway-based controls (e.g., horticultural trade, transport vectors) are established in legislation.

Additional information

PEI Invasive Plant Council

Quebec

Québec has announced a proposed regulation under the authority of the Environment Quality Act, (CQLR c. Q-2 22 oct. 2025). This would be a province-wide, species-specific regulation to prohibit the sale and cultivation of 31 invasive alien plant taxa. While not yet in force, the proposal represents a major shift toward protecting the environment through a preventive regulation focused on trade pathways rather than post-establishment control.

What is proposed for regulation

🌱 20 terrestrial invasive plant

  • Aegopodium podagraria — Goutweed — Égopode podagraire
  • Alliaria petiolata — Garlic mustard — Alliaire officinale
  • Berberis thunbergii — Japanese barberry — Épine-vinette du Japon
  • Celastrus orbiculatus — Oriental bittersweet — Célastre asiatique
  • Elaeagnus umbellata — Autumn olive — Oléastre à ombelles
  • Ficaria verna — Lesser celandine — Renoncule ficaire
  • Frangula alnus — Glossy buckthorn — Nerprun bourdaine
  • Heracleum mantegazzianum — Giant hogweed — Berce du Caucase
  • Heracleum sphondylium — Common hogweed — Berce commune (ou sphondyle)
  • Impatiens glandulifera — Himalayan balsam — Impatiente glanduleuse
  • Lonicera maackii — Amur honeysuckle — Chèvrefeuille de Maack
  • Microstegium vimineum — Japanese stiltgrass — Microstégie en osie
  • Phragmites australis subsp. australis — European common reed — Roseau commun (sous-espèce australis)
  • Pueraria montana — Kudzu — Kudzu
  • Reynoutria × bohemica — Bohemian knotweed — Renouée de Bohème
  • Reynoutria japonica — Japanese knotweed — Renouée du Japon
  • Reynoutria sachalinensis — Sakhalin knotweed — Renouée de Sakhaline
  • Rhamnus cathartica — Common buckthorn — Nerprun cathartique
  • Vincetoxicum nigrum — Black swallow-wort — Dompte-venin noir
  • Vincetoxicum rossicum — Pale swallow-wort — Dompte-venin de Russie

💧11 aquatic invasive plants

  • Cabomba caroliniana — Carolina fanwort — Cabomba de Caroline
  • Egeria densa — Brazilian waterweed — Élodée dense
  • Hydrilla verticillata — Hydrilla — Hydrille verticillée
  • Hydrocharis morsus-ranae — European frogbit — Hydrocharide grenouillette
  • Myriophyllum aquaticum — Parrot’s feather — Myriophylle aquatique
  • Myriophyllum spicatum — Eurasian water-milfoil — Myriophylle à épis
  • Najas minor — Brittle naiad — Petite naïade
  • Nymphoides peltata — Yellow floating heart — Faux-nymphéa pelté
  • Potamogeton crispus — Curly-leaf pondweed — Potamot crépu
  • Stratiotes aloides — Water soldier — Stratiote faux-aloès
  • Trapa natans — Water chestnut — Châtaigne d’ea

Key limitations

  • Regulation is not yet in force; implementation timelines and enforcement mechanisms are pending.

Additional information

Saskatchewan

Regulatory approach

Saskatchewan regulates plants primarily through its Weed Control Act, (SS 2014, c W-11.1) and the associated Minister’s Designation of Prohibited, Noxious and Nuisance Weeds [clauses 2 (r), (s) and (w)].

What is regulated

🌱 65 Terrestrial and aquatic plants are regulated under the Weed Control Act

  • 23 Prohibited weeds
  • 37 Noxious weeds
  • 5 Nuisance weeds

⚠️ Notably, no knotweed taxa (Reynoutria / Fallopia spp.) are listed under Saskatchewan’s Weed Control Act.

💧 6 Aquatic & semiaquatic invasive taxa* are regulated under the Weed Control Act

  • Flowering rush (Butomus umbellatus) – prohibited
  • Loosestrife (Lythrum spp.) – requires control as a noxious weed
  • Eurasian water-milfoil (Myriophyllum spicatum) – prohibited
  • Yellow floating heart (Nymphoides peltata) – prohibited
  • Curly-leaf pondweed (Potamogeton crispus) -prohibited
  • Tamarisk / saltcedar (Tamarix spp.) – prohibited

Key limitations

  • Missing high-risk invasives regulated in neighbouring jurisdictions.
  • Regulation is agriculture-centric, rather than designed around biodiversity protection.
  • Aquatic invasive plant prevention is limited.

Additional information

The Saskatchewan Fisheries Regulations (1995 (SOR/95-233) was updated to prohibit Saskatchewan residents and visitors from importing, possessing, transporting or selling aquatic invasive species. However, currently the focus is only on animals.

Yukon

Yukon does not have a statute or regulation that explicitly lists invasive alien plant species by name. The primary environmental statute Environmental Act (RSY 2002, c 76) provides broad enabling authority, but invasive plants have not been operationalized through regulation.

What is regulated

🌱 No terrestrial invasive plant species are regulated by name under Yukon statute or regulation.

💧 No aquatic invasive plants are explicitly prohibited under territorial legislation.🌱 No formal list of prohibited or regulated invasive plant species exists under Yukon legislation.

Key limitations

  • No species-specific regulatory instruments exist for invasive plants.
  • The hazardous substances framework is indirect and untested for invasive species control.
  • Prevention relies primarily on education, monitoring, and voluntary compliance, rather than enforceable prohibitions

Additional information

Yukon Invasive Species Council
Territorial non-governmental organization providing education, coordination, and reporting tools