Ever heard of a plant coach?

They don’t wear whistles or train plants to grow. No, they instruct people on which plants will survive in their homes, teaching them how to take care of their chlorophyllous children and the way to style the greenery to their liking.

The playing field for these coaches is often Instagram, which has in many ways become a modern iteration of a department store for young people. Businesses tailored to the platform sell clothes, shoes, makeup, wigs, kitchenware — the list goes on.

And houseplants, popular among millennials, have increasingly taken root on the app. As begonias, monsteras and cactuses join microbladed brows, marble countertops and snow white apartment walls as hallmarks of the Instagram aesthetic, young entrepreneurs — or plantrepreneurs, as some call themselves — are building businesses selling plants and teaching others how to keep them alive.

In 2018, 18- to 34-year-olds accounted for 25% of total lawn and garden spending in the United States, up from 23% in 2017, according to the National Gardening Association. Last year, millennials spent more than $13 billion on gardening, the association said. Many nurseries have waiting lists for their most sought-after species.

“Rather than just trying to sell, sell, sell, we create something that is not just about selling plants but is also about education,” said Puneet Sabharwal, 38, who along with Bryana Sortino, 36, runs Horti, a company that offers plants through a subscription service.

Horti, which began in 2017 in a Brooklyn apartment, initially mails customers simple, hardy seedlings. Once their plant-care confidence builds, they are sent species that require higher maintenance.

Sabharwal said that before he and Sortino formed the company, he had noticed that his friends were mostly making their plant decisions in shops, based on the plant’s appearance, as opposed to their ability to sustain it.

Owning a plant, in other words, was more about the way it fit into an Instagram square and less about keeping a living thing alive.

“What ends up happening is that you buy plants that will end up dying, and it kills a lot of owners’ confidence in plants,” Sabharwal said. “If you get plants that will survive, it will give you this sense that you are doing a great job.”

As for the plants that don’t thrive past the initial #plantmom Instagram post, they may even represent a small environmental liability, according to Andrea Ruiz-Hays, the founder of Eco Strategies Group, a consulting firm that works with companies to help them develop more sustainable practices.

“You’re sending additional greens to the landfill,” Ruiz-Hays said. “These plants break down, and they contribute to carbon emissions when it wasn’t needed from the beginning.”

Horti, which says it wants to help customers keep plants out of landfills, is using Instagram to help as much greenery as it can survive.

The company’s Instagram account, which has more than 35,000 followers, has become the best way to drive sales, Sabharwal said.

“I am running the Instagram account more as a gallery, including what is happening in the larger landscape of indoor planting,” he said.

Sabharwal said that nearly all of the company’s plants are imported from Florida to nurseries on New York’s Long Island that distribute them. “Time is money for most of these growers,” he said.

Perhaps unsurprisingly, nurseries are also eager to profit from the rise of plant sales on social media.

Hirt’s Gardens, a plant seller in Ohio that has been in business for 105 years, has experienced a 30% increase in profits over the past decade because of social media, said Matt Hirt, one of the company’s owners.

Hirt, 42, said that the strong sales were in spite of buyers who take advantage of propagation, the ability of certain plant species to spawn new plants from cuttings. (He can tell when someone buys a plant to “love it,” he said, as opposed to buying it simply with a plan to propagate it and sell it forward.)

“It doesn’t take away from my profit,” Hirt said, adding that his internet sales for 2019 were around $1.5 million — nearly double the previous year’s.

Blane Turiczek, 24, the company’s social media manager, said that customers’ habit of tagging the nursery on Instagram helped keep plants flying out of the greenhouse.

“Some of the really cool ones right now have a waiting list,” she said.

A current Instagram favorite, with a six-person waiting list, is the “Pink Princess” philodendron, a houseplant that sells for $50 in a 6-inch pot and has pink and dark green leaves. Some stems unfurl and reveal entirely pink leaves. The nursery usually gets two a week.

A spokeswoman for Instagram said that the company did not have any information about an uptick in plant sales on the platform, but added that “selling plants is popular on Facebook Marketplace.” (Instagram is owned by Facebook.)

Buying plants on social media carries risk, of course.

One danger is plant fraud: You might buy a rare plant as a seedling with the promise that its coveted leaves will eventually show themselves, but it never delivers.

“It happens,” said Nick Cutsumpas, a plant coach who goes by @farmernicknyc on Instagram.

But for most people, he said, keeping a plant that they bought online alive should be relatively straightforward.