PlantLegitIs it illegal? › Japanese knotweed
Where is Japanese knotweed illegal? State-by-state
Also called: Reynoutria (Fallopia) japonica. 26 state lists in our data name it. Checked 2026-10-14.
| State | Status | Official list |
|---|---|---|
| Alabama | Legally regulated — restrictions apply | Class C noxious weed (r. 80-10-14-.04) |
| California | Legally regulated — restrictions apply | Noxious weed (3 CCR § 4500) |
| Colorado | Legally regulated — restrictions apply | List A noxious weed (8 CCR 1206-2) |
| Connecticut | Yes — listed as prohibited | Prohibited invasive plant (Conn. Gen. Stat. § 22a-381d) |
| Delaware | Yes — listed as prohibited | Invasive Plant List (3 Del. C. § 2903; 3 DE Admin. Code 806) |
| Idaho | Yes — listed as prohibited | Statewide Control list |
| Illinois | Yes — listed as prohibited | Exotic weed (17 Ill. Adm. Code 1100.30, Illinois Exotic Weed Act) |
| Indiana | Yes — listed as prohibited | Prohibited invasive terrestrial plant (312 IAC 18-3-25) |
| Kentucky | Not a sale ban — control-only list | Right-of-way noxious weed, control list (KRS 176.051; 603 KAR 3:100) |
| Maine | Yes — listed as prohibited | Do Not Sell list (01-001 CMR ch. 273) |
| Massachusetts | Yes — listed as prohibited | Prohibited plant (MDAR Massachusetts Prohibited Plant List) |
| Michigan | Yes — listed as prohibited | Prohibited species (NREPA Part 413, MCL 324.41301) |
| Minnesota | Legally regulated — restrictions apply | Prohibited – control (MDA list) |
| Montana | Not a sale ban — control-only list | Priority 1B noxious weed (ARM 4.5.207), control list |
| Nebraska | Not a sale ban — control-only list | State noxious weed (25 NAC 10-001), control list |
| New Hampshire | Yes — listed as prohibited | Prohibited invasive plant (N.H. Admin. R. Agr 3802.01) |
| New York | Yes — listed as prohibited | Prohibited (6 NYCRR 575.3) |
| Ohio | Yes — listed as prohibited | Prohibited noxious weed (OAC 901:5-37-01); Invasive plant (OAC 901:5-30-01) |
| Oregon | Legally regulated — restrictions apply | "B" noxious weed (OAR 603-052-1200 quarantine) |
| Pennsylvania | Yes — listed as prohibited | Class B noxious weed (PDA Controlled Plant & Noxious Weed List, 3 Pa.C.S. § 1511) |
| Utah | Not a sale ban — control-only list | Class 1B EDRR (R68-9-3), control list |
| Vermont | Yes — listed as prohibited | Quarantine List Tier 3 (widespread in VT) |
| Virginia | Yes — listed as prohibited | Tier 3 noxious weed; DCR invasive |
| Washington | Yes — listed as prohibited | Quarantined (WAC 16-752-610); Class B noxious weed, control list (WAC 16-750-011) |
| West Virginia | Legally regulated — restrictions apply | Noxious weed (W. Va. Code R. § 61-14A-5) |
| Wisconsin | Yes — listed as prohibited | Restricted invasive plant (NR 40) |
States not shown: we found no listing for Japanese knotweed in the state lists PlantLegit currently tracks. That is not confirmation it is legal there; lists change and some states add plants by separate rule. Check your state agency. Federal list (7 CFR 360.200): not listed. Not legal advice.