How much sun does Poison Hemlock need?

Poison Hemlock grows best in part shade conditions.

When does Poison Hemlock bloom?

Poison Hemlock blooms in May, June, and July.

Is Poison Hemlock toxic to dogs?

Yes. Poison Hemlock is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.

Is Poison Hemlock toxic to cats?

Yes. Poison Hemlock is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.

What pollinators does Poison Hemlock attract?

Poison Hemlock draws bees, beetles, and flies.

Is Poison Hemlock HOA-friendly?

Poison Hemlock takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Poison Hemlock

Name: Pollinator Patch
Author: Pollinator Patch

Conium maculatum

Last reviewed: August 2026

Poison Hemlock is toxic to dogs and cats.

Listed as toxic by the ASPCA Animal Poison Control Center (opens in new tab) (last reviewed 2026-08-15). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435and your veterinarian's emergency line.

Pollinator Patch flags toxic plants so you can choose a pet-safe native alternative for your yard.

Light

part shade

Water

medium

Size

48"–96" H × 12"–24" W

Bloom

May, Jun, Jul

Pollinators

bees, beetles, flies

Native alternatives to Poison Hemlock

Poison Hemlock is not native to the United States. These natives fill a similar role in a planting, matched on bloom season, bloom color and mature size.

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Poison hemlock is an extremely toxic biennial that can grow up to 8 feet tall with delicate, fern-like foliage and small white flower clusters. This dangerous plant is actually a non-native invasive species that should never be planted in residential landscapes. All parts of the plant are deadly poisonous to humans and animals if ingested.

In an HOA neighborhood

Poison Hemlock takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.

Extremely toxic to humans and pets
Invasive species that spreads aggressively
Liability risk in residential areas

Wildlife value

While it may attract some pollinators like bees and flies, the extreme toxicity and invasive nature make any wildlife benefits completely outweighed by safety risks.

Common questions

How much sun does Poison Hemlock need?: Poison Hemlock grows best in part shade conditions.
When does Poison Hemlock bloom?: Poison Hemlock blooms in May, June, and July.
Is Poison Hemlock toxic to dogs?: Yes. Poison Hemlock is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
Is Poison Hemlock toxic to cats?: Yes. Poison Hemlock is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
What pollinators does Poison Hemlock attract?: Poison Hemlock draws bees, beetles, and flies.
Is Poison Hemlock HOA-friendly?: Poison Hemlock takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

Pollinator Patch flags toxic plants like Poison Hemlock and shows pet-safe natives for your ecoregion instead.

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