Gardening with Laurie: Toxic Garden Plants

By Laurie Brown
Reader Columnist

A garden is a source of beauty and joy. The foliage, flowers and wildlife they attract add a lot to people’s lives. But a surprising number of common, gorgeous garden plants can be toxic—some can easily poison and even kill.

Most gardeners are aware that rhubarb leaves are poisonous, and that those pretty nightshade vines with their dark green leaves, purple flowers and bright berries are too, but there are a lot of other perils in the average garden. Did you know that sweet peas are toxic? It takes a lot of them to actually poison a person, but it happens. If the person happens to be a small child, it takes much less to create an emergency situation.

The list of toxic garden plants is extensive. Some merely create dermatitis when handled; others can bring on serious health problems. For instance, aconite (monkshood, wolf’s bane) can create severe problems if any sap gets into your skin via small cuts or sores. One thing I’ve noticed is that if a plant has milky sap, it may cause skin irritation. I’m sure there are exceptions to this. These tend to not be deadly poisons, but if you swallow the sap it can make your mouth and throat get a rash and itch just like it does your hands!

Do you need to avoid all these plants in your garden? The garden would be very bare if we avoided them all. If you have small children, I’d certainly avoid the worst ones like aconite, datura, castor bean plant and daphne with its shiny red berries—or I’d at least remove the berries as soon as they start to form. One idea is to plant all the poisonous plants in one area, and fence it off from children and livestock. I throw weeds and cuttings into the chicken pen, but do not throw anything on this list in. Don’t forget that while plants like the rose are non-toxic, have edible hips and can be made into tea, they’re still poisonous if they’ve been treated with insecticide or mildewcide. I always wear gloves and long sleeves when gardening. Even a very light-weight shirt will protect your skin from poisonous plants unless you’re mashing them up!

There is a good list of poisonous plants at https://ucanr.edu/sites/poisonous_safe_plants/Toxic_Plants_by_Scientific_Name_685/

They rate the plants by toxicity: very toxic, mildly toxic, oxalates which cause irritation of the skin, mouth and stomach and ones that cause dermatitis.

Here are some of the common garden plants that are toxic:

Anything in ranunculi family-the various plants can cause vomiting, liver inflammation, paralysis, and even death:

•Delphinium

•Clematis

•Thalictrum

•Columbine-gastric irritation, arrhythmias

•Anemones

•Larkspur- vomiting, lowers heart rate; can kill In 6 hours

•Aconite (ranunculi but super toxic—wear gloves) heart arrhythmias, cardiac and respiratory arrest

•Bleeding heart-trembling, agitation, respiratory problems

•Wisteria

•Daphne berries and leaves—very corrosive to digestive track, convulsions

•Hellebore

•Lily of the valley-headaches, hot flashes, hallucinations, lowered heart rate

•Daffodils—the worst is the small flowered, fragrant narcissus-vomiting and death

•Datura

•Ricinus (Castor bean plant)

•Iris (mostly in rhizome)

•Gladiola (mostly in bulb)

•Laburnum (Golden Chain Tree) low potency; dose would have to be large

•Elderberry (only the ripe berries are safe)

•Milkweed

•Holly berries

•Potato and tomato leaves

•Primrose

•Rhubarb leaves—oxalic acid; corrosive to throat and stomach; can lead to kidney failure

•Hydrangea—cyanide type toxin, especially in the flower buds

•Foxglove—vomiting; larger amounts cause heart rate problems

•Mountain laurel and azaleas- kidney failure; even honey made by bees visiting it can be poisonous

•Onion and ornamental alliums—poisonous to cats but not humans

•Peony—all parts, skin irritant, nausea, diarrhea

As with any poison, when in doubt, call the poison control center if someone ingests any plant and starts to have odd symptoms. If you don’t know what the name of the plant is, take some with you to the emergency room.