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Is Japanese knotweed illegal in Connecticut?
Sources (1)
Also called: Reynoutria (Fallopia) japonica. Last checked against official sources: 2026-10-14.
Federal noxious weed list (7 CFR 360.200): Japanese knotweed is not listed.
What Connecticut's official list says
| List / legal category | Listed as | List note | What it means |
|---|---|---|---|
| Prohibited invasive plant (Conn. Gen. Stat. § 22a-381d) — no import, move, sale, purchase, transplanting, cultivation or distribution | Polygonum cuspidatum (syn. Reynoutria japonica) | Japanese knotweed | Yes — listed as prohibited |
Effective dates
- The official list entry does not state a separate effective date for this species. See the linked law for when the listing took effect.
Already have it in your yard?
Most state invasive-plant laws, including the list wording above, target selling, distributing, propagating or planting. They generally do not order you to remove a plant already in your yard, but some noxious-weed laws do require control. Read the linked law or ask your county Extension office.
Native alternatives for Connecticut
- Buttonbush (Cephalanthus occidentalis)
- American elderberry (Sambucus canadensis)
- Silky dogwood (Cornus amomum)
- Ninebark (Physocarpus opulifolius)
- Red osier dogwood (Cornus sericea)
Each is recorded as native to Connecticut in the USDA NRCS PLANTS Database state distribution (retrieved 2026-10-14). Check size, sun and soil fit for your site with your local Extension office.
More native swaps with hardiness, light and size →
Japanese knotweed in other states
Alabama California Colorado Delaware Idaho Illinois Indiana Kentucky Maine Massachusetts Michigan Minnesota Montana Nebraska New Hampshire New York Ohio Oregon Pennsylvania Utah Vermont Virginia Washington West Virginia Wisconsin
See every plant on Connecticut's invasive & noxious plant lists, or check any plant.
Not legal advice. PlantLegit summarizes official lists and links the source. Laws change, local (county/city) rules may add restrictions, and the official text controls. "What it means" is our plain-English label; read the exact list wording. Confirm with the agency before buying, selling or removing plants. Full disclaimer.