| A number of heirloom flowers are poisonous. Avoid handling the poisonous ones; wear heavy gloves to be safe. Before adding toxic plants to the garden, consider whether small children will be in the vicinity. |
| The following list of poisonous plants is not inclusive. A poison control center or agricultural extension agency can provide a more complete listing. |
| Genus | species | Common Name |
| Aconitum | various species | Monkshood and others |
| Atropa | belladonna | Belladonna |
| Convallaria | majallis | Lily of the Valley |
| Delphinium | various species | Rocket Larkspur and others |
| Digitalis | various species | Foxglove |
| Hyoscyamus | niger | Henbane |
| Solanum | nigram | Black Nightshade |
| Solanum | dulcamara | Bittersweet |