Wildflowers add to the aesthetic appeal of your garden and promote local biodiversity. While some are edible, a variety of wildflowers are harmful and toxic to humans and animals when eaten or touched.
Some variants are mild irritants, while some can be deadly to anyone who comes into contact with them. When growing your wildflower garden, researching on species that can harm your children, dogs and other pets is important. The following list of wildflowers have various harmful levels of toxicity on humans, pets and livestock.
1. Bleeding Heart (Lamprocapnos spectabilis)
Bleeding Heart is highly toxic to humans and dogs. When it comes into contact with your skin, it can irritate you. If ingested, Bleeding Heart can cause vomiting, tremors and diarrhea.
This perennial plant native to Asia blooms heart-shaped flowers that come in shades of red or pink. The plant occurs in woodland areas. It blooms during spring. It reaches a height of 3ft and spreads 1-3ft wide at full maturity. Bleeding Heart does not require deheading since it is self-replicating.
- Thrives in partial or full shade.
- Requires slightly acidic, moist soils.
- USDA hardiness zones 2-9.
2. Calla Lily (Zantedeschia aethiopica)
This entire plant is poisonous to humans and dogs. It contains the toxic compound calcium oxalate which will cause burning, swelling and numbness in the mouth.
Calla lily produces white cup-like flowers which bloom during spring. It is native to Africa, and thrives in a warm environment with full sunlight exposure. Calla lily propagates through rhizomes or self-seeding.
- The plant reaches a height of 2-3ft and spreads 1-2ft at full maturity.
- Requires moist, well-drained, and acidic soils.
- USDA hardiness zones 8-10.
3. Foxglove (Digitalis purpurea)
This biennial plant is native to Europe and Africa. It is toxic to humans and pets. The seeds, flowers and leaves contain harmful chemicals that cause heart arrhythmias. You should remove this flower from your garden if you have any livestock on the property.
Foxglove produces bell-shaped, purple, or maroon flowers. It does not produce any blooms during the first year, but they appear in early summer of the second year. The plant is self-seeding. Foxglove reaches a height of 3-5ft and spreads 1-2ft at full maturity.
- Requires full sunlight or partial shade.
- Thrives in loamy, well-drained, slightly acidic soils.
- USDA hardiness zones 4-10.
4. Mountain Laurel (Kalmia latifolia)
This North American native evergreen perennial produces spring blooms in clusters of pink or white flowers. All parts of Mountain Laurel are harmful to humans and pets. When ingested, it can lead to vomiting and diarrhea. It causes irritation when it comes into contact with the skin.
Mountain Laurel grows slowly into a thick shrub. The plant should be pruned after the first blooms die out to help it condense into a thick shrub. It propagates by burying stem cuttings in the ground.
- It reaches a height of 15ft and spreads 5-15ft at full maturity.
- Requires partial sunlight.
- Thrives in moist, well-drained, acidic soils.
- USDA hardiness zones 4-9.
5. Oleander (Nerium oleander)
This wildflower has toxic flowers. Its bark contains toxins, which cause a variety of health issues in humans and animals. When ingested the leaves cause vomiting and diarrhea. The plant can be fatal to humans, cats and dogs.
It is native to Asia and the Mediterranean and will produce evergreen foliage and white, pink, or yellow blooms in the spring. It propagates through stem cuttings. Grows to a height of 19ft and spreads 10ft at full maturity.
- Thrives in full sunlight or partial shade. It tolerates drought.
- Requires alkaline, well-drained soils.
- USDA hardiness zones 8-10.
6. Lily of the Valley (Convallaria majalis)
This whole plant is poisonous if ingested. It is toxic to humans, dogs and cats. The plant produces poisonous red berries and can cause nausea, abdominal pain, vomiting and seizures.
It is an herbaceous perennial plant, native to Europe. It is vigorous in growth, especially in shaded areas. It thrives in partial or full shade. Lily of the Valley produces white flowers that bloom during spring. It propagates through its root system in the fall or spring.
- Grows best in well-drained, acidic soils.
- Matures at 6-12 inches high and 9-12 inches wide.
- USDA hardiness zones 3-8.
7. Periwinkle (Vinca minor)
This evergreen perennial native to Europe is toxic to dogs, cats and horses.
Periwinkle has broadleaf foliage and is good for a groundcover plant. It produces blue, purple or white flowers that bloom in spring or summer. It grows at a medium rate, reaching 3-6 inches high and 18 inches wide at full maturity. It is affected by aphids and spider mites, and fungal diseases such as fungal leaf spots.
- Requires full sunlight or partial shade.
- Thrives in alkaline or neutral, loamy soils.
- USDA hardiness zones 4-9.
8. Hydrangeas (Hydrangea spp.)
Hydrangeas are a popular choice for wildflower gardens. It contains a toxic compound that could lead to diarrhea and vomiting if ingested. The leaves, bark, flowers and buds are all poisonous. It is toxic to humans, cats and dogs.
Hydrangeas are native to North America and produce pink, red, maroon or blue blooms from mid-summer to fall. They grow fast to reach a height of up to 15ft at maturity depending on the species. It propagates through stem cuttings buried in the ground.
- Thrives in full sunlight or partial shade.
- Grows well in a variety of soil types.
- USDA hardiness zones 5-9.
9. Angel’s Trumpet (Brugmansia)
This plant emits alkaloids that may lead to headaches after prolonged exposure. All parts of the plant are toxic to humans, cats, dogs and livestock. It is highly irritating when handled with bare skin. Angel’s Trumpet is not a viable plant for a homestead with pets and little children.
It is Native to North America, and thrives in warm climatic regions. It is a perennial that grows as an annual in colder climates. The plant has a shrub-like appearance and spreads rapidly along the ground. It produces white, pink or yellow flowers that bloom in the spring. Reaches a height of 24 inches at full maturity.
- Thrives in full sunlight.
- Grows well in fertile soils with good drainage.
- USDA hardiness zones 8-10.
10. Rhododendron
They are highly toxic to humans and animals. They can lead to diarrhea, vomiting, delirium or anemia if ingested.
It is popular for the green foliage and showy purple and pink blooms during spring. There are various species of rhododendrons, which grow under different conditions. They can grow to a height of 20ft and spread 25ft at full maturity. It is deer resistant and can be grown as a hedge screen.
- Thrives in full shade or partial sunlight.
- Grows well in slightly acidic, well-drained soils.
- USDA hardiness zones 3-9.
11. Iris (Iris germanica)
This plant’s bulb, stem, and leaves are poisonous to humans, cats and dogs. Results in fever, diarrhea and vomiting when ingested. The rhizomes produce a toxin that is harmful to humans.
Iris is popular for flowers with fan-shaped petals and bright colors. The blooms come in a variety of colors, ranging from blue, pink, brown, yellow, red and orange, appearing during spring. It is native to the Mediterranean. Iris is an herbaceous perennial that matures at 12-40 inches high and 1-2ft wide.
- Thrives in full sunlight.
- Grows well in well-drained, sandy soils.
- USDA hardiness zones 3-9.
Summary
These wildflowers appear beautiful at first but are very toxic to humans and animals. You should take care when planting these varieties by keeping them far away from animals and small children. Contact with certain poisonous flowers can be fatal, so caution should be taken when handling them.
