12 Toxic Flowers to Avoid in Your Garden

Lily of the Valley (Convallaria majalis)

In May, this shade-loving perennial ground cover develops stems with tiny, nodding, bell-shaped white flowers on one side of the stem. Your nose will also help you identify it: Lily of the valley has a characteristic sweet scent.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Virginia spiderwort (Tradescantia virginiana)

Wisteria (Wisteria spp.)

This vigorously climbing perennial vine has large showy clusters of fragrant blue or purple flowers in the spring. After blooming, wisteria produces large seedpods with a velvety capsule. After drying, they pop with a startlingly loud noise.

• Toxic Parts: All parts
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Magnifica honeysuckle

Lily (Lilium spp.)

Many lilies are highly toxic for cats. These include the Easter lily with white fragrant trumpet-shaped flowers, the deep-orange tiger lily with its typical brown spots, Asiatic and Japanese lilies, lily hybrids, and daylilies such as the popular Stella de Oro daylily.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Cats
• Non-Toxic Alternative: Canna lilies and other lilies are not members of the Lillium or Hemerocallis genus and therefore are not true lilies

Lantana (Lantana camara)

As a frost-tender evergreen shrub, lantana is often grown as a trailing plant and as an annual in colder climates. It has small dense flower clusters in white, yellow, orange, red, and purple. Sometimes different colors are mixed in the same cluster. The leaves give off a citrus fragrance aromatic when crushed.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, cats. and livestock
• Non-Toxic Alternative: Verbena

Hydrangea (Hydrangea spp.)

There are countless varieties of hydrangea species and cultivars and they all stand out in the landscape by their large flowerheads that are shaped like large round mopheads, lacecaps, or long panicles.

• Toxic Parts: Leaves, flowers, and bark if ingested
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Spirea

Foxglove (Digitalis purpurea)

A close look at a flowering foxglove reveals its most prominent characteristic: The inside of the bell-shaped flowers has many purple to maroon spots with a white ring. The flowers are mostly bright purple, but there are also white, cream-colored yellow, pink, or rose cultivars.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Hollyhock

Oleander (Nerium oleander)

You can identify an oleander shrub first and foremost by the fragrance of its white, purple, or pink flowers. When not in bloom, take a look at the leaves which are narrow and glossy with a distinctive midrib.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, cats, and livestock

Rhododendron and Azalea (Rhododendron spp.)

During their bloom in April, all rhododendron and azaleas stand out by their abundance of lavender, rose, or pink flower clusters. The leaves are dark green, hairless, and leathery and turn purplish in the winter.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Lilac

Mountain Laurel (Kalmia latifolia)

The flower clusters of this broadleaf evergreen shrub are sometimes compared to tiny bowls or bells. The inside of each flower has symmetrical with dark rose- or maroon-colored dots and streaks. 

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, and cats
• Non-Toxic Alternative: Dogwood

Monkshood (Aconitum)

Monkshood flowers have two distinct characteristics – their striking deep purplish-blue to violet color, and an upper sepal in the shape of a hood like the one worn by medieval monks, which gave the plant its common name.

• Toxic Parts: All parts of the plant if ingested
• Toxic To: Humans, dogs, cats, and livestock

Because of its high toxicity of monkshood, it is not a recommended choice unless gardening with proper protective gear.

Angel’s Trumpet (Brugmansia)

As a tropical small tree or shrub, angel’s trumpet is grown in containers in colder climates. The large, drooping flowers come in white, peach, pink, orange or yellow and can grow up to 24 inches long.

• Toxic Parts: All parts of the plant
• Toxic To: Humans, dogs, cats, and livestock

Because of the high toxicity of this plant even when handling it, angel’s trumpet is not recommended in households with kids or pets.

Fall Crocus (Colchium autumnale)

The fall crocus or autumn crocus, which blooms in early fall, has no foliage, unlike the spring crocus. The flower color ranges from lavender to lilac purple.

Toxic Parts: All parts of the plant if ingested
Toxic To: Humans, dogs, cats, and livestock

In households with children or pets, planting crocuses (both summer and fall crocuses) in your yard is not recommended.