12 Toxic Flowers to Avoid in Your Garden

Foxglove poisonous plants lining cobblestone pathway with light purple bell-shaped flowers on tall thin stems

The Spruce / Evgeniya Vlasova

Attractive or fragrant flowers often make us forget that the plants growing in our backyard or on the patio might be toxic for humans or pets.

Whether you are planning to add new plants to your flowerbeds, or you move into a new home and want to check whether the existing landscaping is safe for your children and four-legged best friends, here is a list of common nursery plants that have toxic properties, and suggestions for alternatives. This list is not all-inclusive.

  • 01 of 12

    Lily of the Valley (Convallaria majalis)

    Lily of the valley plant with tiny white bell-shaped flowers

    The Spruce / Evgeniya Vlasova

    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)
  • 02 of 12

    Wisteria (Wisteria spp.)

    Wisteria tree with purple flower clusters hanging from vines

    The Spruce / Evgeniya Vlasova

    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.

  • 03 of 12

    Lily (Lilium spp.)

    Lily flowers with pink and white petals on tall stems

    The Spruce / Evgeniya Vlasova

    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
  • 04 of 12

    Lantana (Lantana camara)

    Lantana plant with tiny pink and yellow flowers clustered closeup

    The Spruce / Evgeniya Vlasova

    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
    Continue to 5 of 12 below.
  • 05 of 12

    Hydrangea (Hydrangea spp.)

    Hydrangea shrub with large leaves and clusters of purple, blue and pink flowers

    The Spruce / Evgeniya Vlasova

    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
  • 06 of 12

    Foxglove (Digitalis purpurea)

    Foxglove poisonous plant with flower stalks and light purple bell-shaped flowers hanging

    The Spruce / Evgeniya Vlasova

    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
  • 07 of 12

    Oleander (Nerium oleander)

    Oleander plant with pink flower blooms and buds closeup

    The Spruce / Evgeniya Vlasova

    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

    Warning

    Due to its high toxicity, Oleander is not recommended for households with small children or pets.

  • 08 of 12

    Rhododendron and Azalea (Rhododendron spp.)

    Rhododendron poisonous plant with ruffled pink flowers clustered together closeup

    The Spruce / Evgeniya Vlasova

    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
    Continue to 9 of 12 below.
  • 09 of 12

    Mountain Laurel (Kalmia latifolia)

    Mountain laurel shrub with pink and white blossoms and buds

    The Spruce / Evgeniya Vlasova

    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
  • 10 of 12

    Monkshood (Aconitum)

    Monkshood plant with purple hood-like flowers on thin stems

    The Spruce / Evgeniya Vlasova

    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.

  • 11 of 12

    Angel’s Trumpet (Brugmansia)

    Angel's trumpet shrub with light pink trumpet-shaped flowers

    The Spruce / Evgeniya Vlasova

    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.

  • 12 of 12

    Fall Crocus (Colchium autumnale)

    Fall crocus plant with lavender flowers in sunlight

    The Spruce / Evgeniya Vlasova

    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.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Convallaria majalis. NC State Extension.

  2. Virginia Creeper and Wisteria Toxicity. National Capital Poison Center.

  3. Lovely Lilies and Curious Cats: A Dangerous Combination. U.S. Food and Drug Administration, 2021. 

  4. Daylily 'Stella d'Oro', Denton County Master Gardener Association

  5. Lantana camara. NC State Extension

  6. Hydrangea. NC State Extension.

  7. Hydrangea. ASPCA.

  8. Digitalis purpurea. NC State Extension

  9. Nerium oleander. NC State Extension.

  10. Rhododendron. NC State Extension

  11. Kalmia latifolia. NC State Extension

  12. Aconitum. NC State Extension.

  13. Guide to Poisonous Plants. Colorado State University.

  14. Gardening with Pets. University of California Agriculture and Natural Resources

  15. Guide to Poisonous Plants. Colorado State University.