When more than $20,000 worth of bonsai were stolen from Fukujyuen, a shop selling the carefully cultivated mini trees in Japan’s Gunma prefecture, Shuichi Baba felt anger but also deep sadness for the miniature trees he had lost.

“I even blamed myself,” Baba said of the disappearance of more than a dozen junipers and other plants he had nurtured for as long as two decades. “Why couldn’t I have woken up in the middle of the night to stop it?”

Baba isn’t the only one to see his living creations purloined in the dark. There were about 30 cases of theft last year, according to the Nippon Bonsai Growers Cooperative. Although crime data isn’t readily available, the group says such incidents are on the rise and happening across the archipelago, in areas ranging from Shikoku, the smallest of Japan’s four main islands, to Tokyo’s environs. Two Vietnamese accused of stealing ¥18.8 million ($127,000) worth of bonsai in 2024 faced trial in Kumamoto prefecture.

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The miniature potted trees, carefully cultivated over many years, are becoming increasingly popular around the world, much like Japanese food and culture. The global bonsai market is projected to be worth almost $22 billion by 2033, jumping from $8.42 billion last year.

"As bonsai has become more recognized overseas, the thefts have been on the rise too," Baba said.

Bonsai is an art form that dates back more than 1,000 years. Although budget trees can be found for around $20-$50, many have a much higher price tag — a well-known white pine was offered for ¥100 million, or $670,000 at current exchange rates, in 2011. A website called bonsainut.com has forums with hundreds of thousands of messages where people talk about bonsai and share tips every day.

While some people see bonsai as a regular houseplant, others consider it an art form, according to Karen Harkaway, president of the American Bonsai Society. That could also explain the rising thefts.

“Bonsai is different things to different people — there are a large number of people who just want to have a small tree in a pot and enjoy that,” said Harkaway, who has been growing bonsai for about 20 years and saw the ¥100 million bonsai in person in 2011. "On the other end of the spectrum, there are people who are real artists who have a sense of creativity and style that they're looking to get to."

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The number of active members in the American Bonsai Society has grown by about 40 percent in the past decade, especially among younger people who learn about it online, according to Harkaway. She said she also knows people in the US who have had their bonsai stolen, which she attributes to resellers.

Booming demand is fueling exports of the manicured plants. About ¥906 million worth of bonsai sold abroad in 2024, almost double the amount from 2019, according to the Ministry of Finance.

In Aichi, a prefecture in central Japan, there have been at least 20 cases of stolen bonsai, including attempted thefts, since the end of 2023. “It is thought that the thieves met their accomplices on social media and did it to receive payment from those people,” said a police department spokesperson.

The cooperative recommends that bonsai shops install security systems and work with the local police to prevent such measures. But for Baba, even having a camera didn’t help prevent the incident. Bonsai can be vulnerable because they are usually cultivated outdoors and are potted, making them more portable than plants rooted in the ground.

“It’s difficult to take decisive measures since bonsai need to be looked after outdoors,” said a spokesperson from the cooperative. “As it takes a considerable amount of time to construct bonsai, and they need to be continuously cared for, there is a risk that the number of existing bonsai will decrease.”

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The Aichi Prefectural Police said owners should ensure that locations of the bonsai or details on when the owners will be away are not posted online. They also recommend communication among communities about unfamiliar people, as thieves sometimes scout out the area beforehand. GPS tags on the plants can also help locate them after they’ve been stolen, according to the police.

Baba said bonsai shops may have to reconsider how they take care of their prized possessions; after the theft, he’s taken more measures such as raising the height of his walls, installing a security system and adding more cameras.

“I’m very thankful that bonsai has become popular and that its value is becoming recognized by more people,” said Baba. “But I really hope that these thefts will stop.”