Are There Plants in Your Garden That Could Poison Your Pooch?

Last Updated on December 8, 2023 by Simon Treulle

When I was younger, I could murder most plants just by glancing in their general direction. My mother once gave me a potted philodendron — adorned with an encouraging note that said, “Here, dear, this has been around since the Victorian era”— and within a week, every leaf was a withered beige husk.

Yet surprisingly, something happened around the time I purchased my first home. I began talking to my plants, in much the same way I’ve always talked to my dogs. And the plants, like the pups, really seemed to like it.

I started cultivating more houseplants, and then a small outdoor garden. Eventually, I took some horticulture classes, and before too long, I was on a first-name basis with the botanist at our local nursery. I have to admit, thriving open-air foliage really adds a lot to the general backyard ambience — though my rescue-pooch Grant largely seems to regard it as a worthy tinkle target.

Dog helping in the garden by Shutterstock.
Dog helping in the garden by Shutterstock.

The point is, I understand that many of us weren’t born with a natural green thumb — so we sometimes appreciate horticultural insights and advice. With spring approaching, I thought it might be useful to share a list of popular outdoor plants and gardening materials that can be particularly harmful if the family pooch ingests them. Given the propensity of most pups to sniff, nibble, and investigate, sometimes having this information before we begin prepping and planting can prevent big problems later.

1. Mulch

Different varieties of mulch by Shutterstock.
Different varieties of mulch by Shutterstock.

Surprise! I didn’t even start with an actual plant. That’s because mulch is a staple in so many gardens. In fact, there’s a very popular mulch variety known as cocoa mulch, which is sold at most nursery and garden supply chains. It’s a gorgeous, rich brown color. It has a yummy-sweet fragrance, reminiscent of dark chocolate. That’s because it’s made from cocoa bean hulls, which contain the pup-problematic ingredient theobromine.

This substance, also found in actual chocolate, is highly toxic to dogs and cats. Unfortunately, since this mulch smells almost edible, many pups actually try to eat it — and it can kill them. So always read the package before you purchase your mulch. We prefer more pet-friendly mulch alternatives, including cedar or shredded pine, for our garden.

2. Rhododendron and azalea

Pink satsuki azaleas by Shutterstock.
Pink satsuki azaleas by Shutterstock.

Depending upon the variety, azaleas can have no scent, a light aroma, or a nearly overpowering fragrance. But both azaleas and rhododendrons have still been known to attract nature-loving pups. That’s why it’s important to know that each species contains toxic compounds known as grayanotoxins.

When ingested, grayanotoxins can cause depression of the central nervous system — along with vomiting, drooling, and diarrhea. Cases of severe poisoning can actually lead to coma and fatal cardiovascular collapse. Find a more pet-friendly flowering plant for your yard.

3. Lilies

Lilies by Marybeth Bittel.

Lilies are often described as distinctively perfume-y or sweet-smelling. Yet they’re actually considered one of the most toxic plants for cats – and they’re problematic for dogs, as well, because it’s not entirely clear which part of the plant is so poisonous. Ingesting even tiny amounts can potentially lead to serious, irreversible kidney damage. So keep them out of your garden, and if you’re walking your dog, appreciate their fragrance from the safety of a nearby path or sidewalk.

There are many resources online for reading about the different types of lilies. For example, here is a resource from about peace lilies.

4. Oleander

Oleander by Marybeth Bittel.

Ever read the Janet Fitch novel — or seen the Michelle Pfeiffer film — called White Oleander? A literary pal once explained to me that this title was chosen because it alludes to something breathtaking yet deadly. Sorry, beauty lovers: Every single part of the incredibly hardy oleander plant is extremely toxic. Ingesting any amount can lead to gastrointestinal issues, hypothermia, abnormal heart function, even death for your dog. Another no-no for the yard.

5. Castor bean

Castor bean by Marybeth Bittel.

Occasionally, you run across a troubling news story about items that have been laced with ricin. This highly toxic protein even played a sinister role in the popular series Breaking Bad. It can cause loss of appetite, pronounced abdominal pain, drooling, vomiting, dehydration, and excessive thirst. So it’s well worth noting that castor beans are a known source of ricin. In fact, severe castor bean poisoning can cause seizures, tremors, coma, even death.

Even more problematic, the leaves of the castor bean can be somewhat tough to spot when mixed with other types of green foliage. If you have a canine who likes to nibble experimentally, keep castor bean off your to-plant list.

6. Sago palm

Sago palm by Shutterstock.
Sago palm by Shutterstock.

Having braved many a snowy winter, I’m a big believer that every garden can benefit from one or two tropical touches. Though technically this low-growing favorite isn’t a true palm tree at all, but rather an ornamental cycad. The most poisonous part of the sago palm are its seeds — but when it comes to our pups, every part of the plant poses a potential health risk. Eating just a seed or two can lead to vomiting, diarrhea, seizures, and liver failure. Ingesting bits of the leaves or bark can also lead to general weakness and gastrointestinal issues. Keep this tropical stunner off your property.

7. Chrysanthemum

Chrysanthemums by Marybeth Bittel.

These flowers are certainly pretty to behold, but they also contain compounds called pyrethrins. When ingested, these can lead to drooling, vomiting, and diarrhea. If your dog consumes enough of the plant, you may also see severe lethargy, weakness, and loss of coordination. They are not recommended for a pet-friendly garden.

8. Yew

Yew by Marybeth Bittel.

The hardy, shade-loving yew is part of a species of ornamental evergreen that’s an extremely popular garden choice. However, be aware that all parts of this plant are highly toxic to dogs and humans, due to a compound called taxine. Consumption can lead to serious gastrointestinal upset, pronounced trembling, breathing difficulties, central nervous system issues, even complete cardiac failure, and death. Keep yew off your property.

9. Tulips

Dog with tulips by Shutterstock.
Dog with tulips by Shutterstock.

These are some of my absolute favorites when it comes to adding a cheerful pop of color. Just bear in mind that if tulip bulbs are ingested, they can pose serious problems for a pooch. The bulbs themselves contain known toxins that can lead to a range of gastrointestinal issues. Certain dogs may even experience convulsions and cardiac abnormalities. This is also important to keep in mind if you like to place a few colorful tulips in a vase to brighten up your home.

Finally, a concluding word of reassurance: Many pet owners cultivate these popular plants with no problem whatsoever. The key is knowing which varieties are harmful, and making absolutely sure family pets do not have access to them. Gardens and greenhouse areas can be tranquil, sunny, relaxing spots to enjoy with our furry friends. Taking careful precautions in advance will help ensure that everyone gets maximum enjoyment from warmer-weather time spent outdoors.

Read more by Marybeth Bittel:

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