Does a Houseplant Need to Glow for You to See It as Alive?

The gallon pot of white petunias I held on an otherwise ordinary subway train, on an otherwise ordinary Thursday in March, would have looked to anyone else like an ordinary houseplant. But I knew better. An hour before, Karen Sarkisyan, one of the plant scientists responsible for this petunia’s existence, had dropped it off at my office. He warned me that my petunia had spent a while in transit, and might not immediately put on a show. Still, I’d rushed the petunia into a windowless room. My eyes took a moment to adjust to the darkness. But then I saw it. The white blooms gave off a green luminescence. The glow was indeed faint. But it was a plant that was glowing. I gasped.

The company that makes these plants, Light Bio, had opened orders to the general public just a few weeks prior. A first run of 50,000 sold out. The company planned to double that by year end, and has already taken orders for two weddings. Sarkisyan was in town to speak with representatives from a futuristic planned city interested in a bulk order. Light Bio will ship the first specimens—smaller, four-inch plants—to its buyers in the coming months; for now, the petunia I held was one of the only large, mature plants in the world.

Every millisecond of light represented the work of the plant’s metabolism, which Sarkisyan and a team of other scientists had hooked up to genes from a glowing fungus. After a few hours in the sun, my beleaguered specimen would have the energy to glow brightly. But even in that first moment, I was smitten. On the train ride back to my apartment, I tried in vain to keep the pot from jostling and the delicate blooms away from other riders’ backpacks. This was the first glowing plant approved for sale, I thought. People better stand back.  

I was surprised at my immediate capture. I had just written a book about plant behavior, and I knew that plants were anything but passive objects or inert ornaments. I understood that they used complex forms of communication, made strategic decisions about how to grow, could finely sense their neighbors, and had enough photoreceptors to detect colors beyond our own perception. Yet despite all I knew, it was hard, with my human senses, to actually register their incredible alacrity. The glowing was different. I was watching the plant live.

If anything, this glowing plant and the commercial glowing plants that are sure to follow have the best chance of anything I’ve seen at breaking the human tendency to conceive of plants as somehow less alive than animals. We are very biased toward things with faces, and creatures that move fast enough for us to perceive their motion. The state of botanical unseeing has a name: Botanists call it “plant blindness.” In recent years, though, new research has been revealing how thoroughly alert plants are, provoking new questions about whether we should consider them intelligent or possibly conscious. Seeing a bioluminescent petunia at precisely this moment could help people recognize plants for the creatures they are. Do houseplants need to glow for more of us to see them as alive? Ideally not. But a glowing plant might be the set of conceptual training wheels that eases the way there.

To make that leap, people need to understand that the glow reflects a flurry of activity inside the plant, a signal of its literal life force. This particular plant glows because of a cluster of five genes, some of which scientists borrowed from the bioluminescent fungus Neonothopanus nambi. The mushroom genes essentially compel the plant’s metabolism to reroute itself through a light-emitting process before carrying on with its tasks. The glowing takes some of the plant’s energy but doesn’t seem to harm the plant. Sarkisyan said the life span of the glowing petunias is the same as that of their unaugmented brethren—at least one growing season: “If you just prune it regularly and give it enough light and all that, it will live for quite a long time.” The petunias can also be propagated, and the seeds collected and planted. The USDA determined that the plant was unlikely to attract more pests than the average petunia and approved it for cultivation last year. You can even plant these petunias in your garden if you want to.

Bioluminescence itself is largely a mystery, despite being present in thousands of organisms. “No one knows the real function of fluorescent proteins,” Sarkisyan told me. Some cases seem straightforward: Scientists think that bioluminescent algae luminesce when touched in order to deter the small fish that eat them, by threatening to attract larger fish. In mushrooms, the purpose is unclear. Initially, scientists believed that fungi were attracting insects to spread spores, but newer research has shown that insects are not particularly attracted to their light. Plus, some species of glowing fungi glow only in their belowground mycelium, where it would be of no use to spore-spreading. Our relatively limited understanding of the glowing phenomena, though, won’t stop us from making more things that participate in it.

To see what other scientists thought of this petunia, I emailed Simon Gilroy, a botanist who leads a lab at the University of Wisconsin at Madison that uses green fluorescent proteins to study how a plant sends signals through its body. But the fluorescence of those proteins—originally synthesized from a jellyfish—is visible only with specialized lights, unlike the petunia now in my house, which glowed on its own. When I visited Gilroy’s lab in 2022, he showed me a tiny plant beneath a microscope lens, handed me a pair of tweezers, and instructed me to pinch it. I watched as a green luminance moved through the entire plant body: The experience permanently changed my view of plant life. Here was a lively, dynamic creature that absolutely knew I was touching it.

Gilroy quickly wrote back: “I actually have 2 of those luminescent petunias on pre-order.” I sent him some photos of my prized preview specimen. After a day in direct sunlight, it was now glowing with a certain verve. I was happy to sit for a while in the dark, watching the blooms emanate a matte green glow, similar in quality to moonlight. The light kept to itself: If you looked in another direction, you wouldn’t know it was there. Only the flowers glowed perceptibly. The newest buds glowed brightest.

Later, on the phone, Gilroy told me that the plant’s existence was a genuine breakthrough, and an elegant piece of science. “It’s taking what evolution has already equipped biology with and using it in an incredibly clever way,” he said.

These plants’ ability to generate their own light opens up a range of possibilities, Gilroy said: Maybe one day grass on the sides of runways could light up to help planes land. Or, more intriguingly, “you could imagine making plants that just self-report what’s going on inside them.” . If plants could tell us more about themselves, that might help solve mysteries about their experience of the world.

The scientific applications of being able to implant genes for bioluminescence into other creatures are formidable: They could hypothetically be used to visualize tumor growth in lab animals, or insulin activity. But finding a way to make animals glow as brightly as plants using the same technology is still a ways off, and not something Light Bio is attempting. Instead, its next order of business is making plants that glow additional colors—yellow, orange, and red.

One night, after the sun went down, I closed my window shades and waited for my eyes to adjust. The glowing blooms came into view, their edges sharpened. A clean, sweet scent floated out a good three feet from the pot. I plucked off a bloom. I wanted to see what watching the light in it dim would feel like, whether that would bring me closer to some understanding about the process of living. It pained me a little to do it, but on the plant's inner stems, dozens of tight little buds were poised to unfurl soon. A flower is always an ephemeral thing.

The decapitated bloom glowed as brightly as ever. I waited maybe an hour, cradling the flower in my palm. Still it glowed. It was already late. I put it on my bedside table and looked one last time: still glowing. The next morning—still glowing. Sarkisyan told me it could probably carry on  like that for days. Its metabolism would eventually slow down and then cease. It would die, at last. But then I remembered that plants can reproduce themselves, if necessary, from almost any part of their body. Plants are decentralized, made of modular parts, one of their many superpowers. This little bloom, with barely an inch of stem attached, still likely had enough energy within it to re-create an entire plant body, if given the right conditions. I had known that, and the plant didn’t need to glow for it to be true. Still, it reminded me how little we understand about plants and their bizarre genius. We can strain to comprehend that without a glowing reminder. But it certainly doesn’t hurt to have one.