Let's get to the root of this question.

At the heart of veganism is a principle that we see in many philosophies through history and around the world: do no harm. But you don’t have to be vegan to want to eat ethically, reducing the amount of harm you put on your plate. The first step is often taking a step back from your meal to see your food as more than ingredients: what are you actually eating?
Recognition of the living animal on our plates, and the pain and suffering they’ve gone through to create one (maybe even not that good!) meal, is the first step for many of us who pursue a plant-based diet. By choosing not to eat animals, we want to pursue an ethical lifestyle that causes less pain to other living creatures. So it’s not a surprise that we might also ask—hang on, what about plants?
Do plants feel pain? What ethical responsibilities do we owe to those green (and red, and yellow…) lifeforms that share our planet? The answer is… it’s complicated.
First things first: what is pain?
We know it when we feel it. But pain is actually a complicated phenomenon, and none of us feel it in exactly the same way—not two people, not two sheep. In its essence, pain is our body’s warning system, telling us that something in our circumstances has gone badly wrong and hoping that we’ll do something to amend that. It alerts us to harmful changes in the body (like cancer) or circumstances (like touching a hot stove).
That warning system is activated in humans and animals by three important factors: our nociceptors, nervous systems, and brains. Nociceptors are the nerve endings specifically intended to detect pain and alert us to its existence, and our nervous systems carry this alert to our brains, which activates the ‘hurt’. Ouch!
No, plants don’t feel pain
Conventional wisdom is that plants don’t feel pain because, unlike humans and animals, they don’t have those three important biological structures: nociceptors, nervous systems, and brains. Without these three elements, they can’t detect or feel pain.
That means that when you accidentally trample a flower or, more importantly, eat a carrot, the plants do not feel any pain as a response to your actions. Plants experience the world as life or death: if they are left living, they will simply heal, putting out new flowers or growing new carrots. If they die, they die. But most scientists believe that pain and suffering do not come into the equation.
And yet…
Yes, plants do feel pain
There are arguments that plants do experience pain, albeit in a different form to the way humans and animals do.
Firstly, plants undoubtedly respond to sensory input. All plants react to light, using it to grow and develop and even track seasons and time. Some plants have very visible sensory reactions: think of the Venus Flytrap, with highly reactive pressure sensors that trap flies and other small insects, or the sensitive plant, which rapidly collapses its leaves when touched.
Scientists have used these sensory reactions as well as other fascinating elements of various plants’ lives to argue that they can indeed feel pain. Professor František Baluška, a plant cell biologist at the University of Bonn, believes that plants feel their own version of pain in order to react appropriately, arguing that this is visible even on a molecular level as plants produce substances which reduce pain. Other scientists have discovered that plants release gas when they’re cut—the plant equivalent of a cry of pain.
It’s difficult to prove definitively that something doesn’t happen, because there’s always the possibility that we simply haven’t understood how something does happen. A plant doesn’t have a brain, or nerves, or pain receptors—as we humans understand them. Maybe it has something else. After all, people used to argue (and some still do) that animals don’t feel pain or experience sentience. It’s possible that in a hundred years, people will be aghast that their ancestors thought plants didn’t, or couldn’t, suffer.
Beyond the question: a bad faith argument?
It’s important to keep a clear and open mind about the possibility that we’re wrong or yet to discover the ways plants express pain. But it’s also true that over the years, people have repeatedly used the “do plants feel pain” argument to discredit or laugh at those who advocate for kindness toward animals.
The question implies hypocrisy on the part of vegans and vegetarians, by suggesting that they care about animal suffering and not plant suffering. Instead of engaging openly with the vegan principle of reducing harm wherever possible, it deflects the argument into a “well, what about…” state that is hard to argue with. It’s rarely used to foster meaningful discussion about ethics or science. Instead, it trivializes vegan principles or is used to score rhetorical points.
And it also ignores one very large, harmful attack on plants…
Eating animals hurts plants
It’s not pain in the sense of an immediate physical sensation. But one of the most dangerous and harmful forces facing plants? Eating meat.
This is because the factory farming complex is a scourge on not just animals, but our whole planet. In order to make room for cattle grazing and other forms of animal agriculture, companies are chopping down billions of hectares of forest. The largest consumers of plant life on our planet are farmed animals, raised for slaughter: livestock consumes 83% of farmed land. That’s a whole lot of plants.
Ironically, one of the best ways to protect the biodiversity of plants on our planet (and the planet itself) is by eating only plants. A vegan diet results in 75% less climate-heating emissions, water pollution and land use than a meat-rich one. So if you really want to reduce the pain plants may or may not feel, eating only plants vastly reduces the negative impact you’ll have on plant life at large. And then we'll ensure we all have a planet left to enjoy, if we finally do discover that plants feel pain.