Is Your Plant Addiction Environmentally Friendly?

How green is your "green thumb," really?

Assortment of plants in a showroom
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The houseplant market is thriving. In 2019, an annual National Gardening Association survey revealed that U.S. houseplant sales increased by 50%, to $1.7 billion, in three years, and the trend has continued to snowball since then. The term "indoor plants," for example, received two and a half times more Google searches in May 2020 than it received just two months prior. Another survey of about 1,000 people who had bought houseplants after March of that year revealed that 12% were first-time plant buyers, too. But the booming horticultural hobby, innately green as it may seem, might not be so environmentally friendly.

Depending on how you procure your leafy darlings—and from where—your houseplant-buying habits could be accelerating the climate crisis. Here are some of the plant industry's biggest environmental problems, including "plant miles," plastic waste, and issues surrounding peat moss harvesting.

Where Do Houseplants Come From?

Large, modern greenhouse full of various plants

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Most houseplants thrive indoors because they're native to tropical and subtropical climates. The beloved Swiss cheese plant—one of the most Instagrammed houseplants, racking up a combined 3.5 million posts under the hashtags #swisscheeseplant, #monstera, and #monsteradeliciosa (its botanical name) as of 2021—hails from Panama and southern Mexico. Devil's ivy—aka golden pothos—is native to the Solomon Islands, the Chinese money plant to southern China, and snake plants and fiddle-leaf figs from western Africa.

To grow these plants outside of their natural habitats, their preferred conditions must be replicated by vast, energy-sucking greenhouses. A 2016 World Foritculture Map commissioned by the Dutch financial services company Rabobank and florist conglomerate Royal FloraHolland showed the global trade flow of cut and living plants sprouting directly from the crown of Holland, where automated greenhouses are equipped with artificial lighting and high-tech irrigation systems to keep the flora happy.

In the U.K., specifically, where houseplant sales saw an 82% increase from July 2019 to July 2020, $308 million worth of living plant imports came from its Netherlands neighbor. The 2016 map also showed that the U.S. exports no shortage of living plants itself, mostly to Canada and Mexico.

The environmental impact of this system is twofold: the energy required to maintain near-tropic conditions in a greenhouse year-round and the emissions generated from transporting product across international borders. Although it's impossible to measure the exact carbon footprint of the indoor plant trade, one shipping company's emissions calculator determined that a single standard-size shipping container traveling from Amsterdam to New York City could produce half a metric ton of CO2.

Houseplants and Plastic Waste

Person holding two plants in plastic pots

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Plastic pots have been the U.S. plant industry's predominant container type since the '80s. Most houseplant pots are made from polypropylene (PP, #5), which isn't widely accepted by curbside recycling services. In fact, only 1% of it gets recycled in the U.S.

According to a 2020 report by the Association of Professional Landscape Designers, "the widespread acceptance and use of plastic pots made possible the growth and efficiency of the green industry" between 2015 and 2018, when the number of floriculture producers in the U.S. increased by 12%. The most recent estimate of how much plastic is produced for indoor and patio plant containers—from 2013, even before the 2020 surge—was about 216 million pounds annually. Nursery Management magazine reported that 98% of them wind up in landfills, where they take 20 to 30 years to decompose.

The Problem With Peat Moss

Overhead view of expansive peat bog post-harvest

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One of the biggest problems with houseplants is the one perhaps least known. Peat moss is a principal ingredient in most potting mixes because it prevents plants' nutrients from washing away during waterings, can hold several times its weight in moisture, and can release that moisture into plant roots when needed. But harvesting this multipurpose fibrous material requires constant disturbance of peatlands, the largest terrestrial organic soil carbon stock on the planet, storing almost 100 times more carbon than tropical forests.

Peatlands cover 3% of the Earth's surface, with northern Europe, North America, and Southeast Asia containing the largest amounts. The soil-like matter is harvested by scraping the surface of peat bogs with a tractor, a process that releases stored CO2 back into the atmosphere. According to the IUCN, about 10% of global greenhouse gases from land use come from damaged peatlands, and the level of destruction multiplies when those peatlands catch fire, which they often do when harvested in dry conditions.

The fires that ravaged Indonesia's peat swamp forests in 2015 resulted in greater daily emissions than what the European Union puts out by fossil fuel burning—and this happens regularly. Burning peat is more polluting than burning coal and can have severe effects on human well-being.

In addition to the fire risk, harvesting peat pollutes drinking water and causes biodiversity loss. The IUCN attributes the 60% decline in the Bornean orangutan population over a 60-year period to the loss of peat swamp habitat. The primate is now listed on the IUCN Red List as critically endangered.

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