In Praise of Poisonous Plants

Convallaria majalis_Lily of the Valley_HudsonGardens-CO_LAH_5740Maybe hemlock has the right idea.

I’ve always avoided incorporating poisonous plants in my garden. When our children were small, I was worried that they would eat a leaf or berry. Now we have small grandchildren who come to visit. Years ago, back in California, we tore out the oleanders and privets, replacing them with artichokes, strawberries, and other “edible landscaping.”

Callirhoe involucrata - Winecups @SantaFeGreenhouses 20080628 LAH 035We’ve lived in Colorado for over 24 years, but recently we moved into a new house in a new neighborhood. The developer must have displaced a huge rabbit colony. Huge herds of munching bunnies roam my yard, looking to dine on anything green. I’ve discovered that cottontails relish zinnias, coneflowers, and winecups (left). The crocuses bloomed—and were eaten within a few hours (even though veterinary websites claim they’re hazardous to pets).

Cottontail Rabbit_HudsonGardens-CO_LAH_5917As some of my favorite plants disappear into the hungry beasts, I’ve begun to search out alternatives that they will not eat. All the literature on “rabbit resistant” species warns that nothing is actually rabbit proof. That may apply to plants with scented foliage, such as catmint and mint hyssop. But I want something that will fight back. Happily, some plants have been doing just that for millions of years. Here are some plants with poisonous leaves that should at least make the bunnies very sick, if not very dead. (Just remember, often the rabbits have to try them to discover they’re inedible.) I’ve either successfully grown them myself, or they’re thriving in area gardens.


  • Hyacinth_DBG-CO_LAH_6788When it comes to bulbs, daffodils are a good bet. Although tulips contain the same toxic glycosides as daffodils, and can make both people and animals sick, for some reason rabbits (and squirrels and voles) eat tulips but not Narcissus. Plus, they do well in our soils and climate. I have lots of daffodils around the house, and their cheerful yellow flowers do wonders for my spring-starved soul.
  • Other poisonous bulbs include snowdrops (Galanthus), Siberian squill (Scilla) autumn crocus, Siberian iris, hyacinths, lily-of-the-valley (top), and lilies.

Annuals & Perennials

  • Nicotania alata, also known as flowering tobacco, is an annual with pretty, tube-shaped flowers on tall stems.
  • Lobelias come in many forms. Hanging containers often include trailing stems of intense blue or white annual lobelia (below, left). Cardinal Flower, Lobelia cardinalis, is a tall perennial that prefers damp soil and full sun. Its spikes of bright red, trumpet-shaped flowers attract hummingbirds.
  • Foxglove is the source of the drug digitalis, which is fatal in large quantities.  Many are biennials, but a perennial species that is particularly well adapted to the Front Range is the PlantSelect® winner Digitalis obscura ‘Spanish Peaks  (aka ‘Sunset’) (below, center).
  • Monkshood and other plants in the genus Aconitum are a striking addition to a perennial border, with their tall stems and dark purple flowers (below, right).
  • Plants in the genus Delphinium include larkspur and the classic blue delphiniums. Young plants are particularly poisonous. Dwarf delphiniums are more drought-tolerant and survive our spring winds better than traditional, taller cultivars (below, left).
  • Bleeding Heart is a lovely shade-loving, spring-blooming perennial that then dies back for the rest of the season (below, right).
  • Black Hellebore (aka Christmas Rose), Helleborus niger, won’t bloom here in winter, but it is hardy to zone 3. While it might not kill the munching rabbit, it tastes bad, and eating it causes burning of the eyes, mouth and throat.
  • Lupines are familiar wildflowers, but there are also cultivars with large, extremely showy flowers that are terrific in a flower border. Short-lived perennials, they may only live a few years, but they’re easy to start from seed (below, left).
  • Bloodroot (Sanguinaria canadensis) prefers at least part shade, especially at higher altitudes, and consistently moist (but not soggy) soil. The low-growing foliage spreads as a ground cover, but fades and disappears in late summer. The impressive, solitary white flowers appear early in spring, making a lovely display in a woodland setting (below, right).


  • Brooms in the genus Cytisus are invasive in other parts of the country, but here we appreciate their tenacity in the face of difficult growing conditions. C. purgans ‘Spanish Gold’ is another PlantSelect® winner. It’s a tedious job pruning out the bare, winter-killed stems every spring, but the incredible flush of bloom that follows makes it worthwhile (below, lower right)
  • Elderberries (Sambucus) are large shrubs or small trees with attractive divided leaves and huge sprays of white flowers followed by red berries (below, left).
  • Yews (Taxus sp.) can be shrubs or trees. These conifers aren’t used extensively along Colorado’s Front Range, although they are hardy to zone 4 and have attractive, evergreen foliage (below, upper right).


  • Eggplant_DBG_LAH_7644Tomatoes, potatoes, eggplant, tomatillos, and peppers are all in the nightshade family. The fruit or tubers are edible (and delicious), but the leaves are poisonous.
  • Rhubarb leaves are poisonous, which is why we only eat the stems. (Of course, the stems are probably the part that the rabbits notice first.) So far, mine is untouched.

There are many more beautiful plants that are poisonous or distasteful to wildlife. I hope my bunnies learn their lesson, and concentrate on eating the weeds instead. That, I can live with!


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