Gardening, especially on residential balconies, has taken off among young urbanites since the COVID-19 pandemic. The new gardeners, who see it as a stress reliever and a way to live more sustainably, have boosted a niche opportunity for many retailers.

In the first quarter, the number of people who bought seeds online in China surged by over 100 percent year-on-year, and most buyers are from Beijing, Shanghai and Hangzhou, Zhejiang province, according to a recent report by Taobao, an e-commerce platform of Alibaba Group.

This spring, the best-selling seeds were coriander, followed by leek, watermelon, pepper and tomato. The booming sales of seeds have also driven sales of supplies and equipment, such as potting soil, shovels, spades and watering containers, according to Taobao.

A few weeks ago, David Ferns, who is from the United Kingdom and works in the field of education in Beijing, started to grow tomatoes on his balcony. With more time spent at home due to the pandemic, he began to get interested in planting and searched for advice online.

He cited the pandemic as one reason to try out his green thumb, but added that it's mainly for fun.

"I tried to adopt a more sustainable lifestyle, even in a simple and modest way, and it's economical, too. There are things in our daily lives that we can do more by ourselves, rather than relying on increasingly complex supply chains," he said.

A number of young urbanites are using more sophisticated equipment to grow fruit and vegetables on their balconies, such as special lighting, smart watering devices and Styrofoam growing containers, which are lightweight and help insulate roots.

The trend has benefitted domestic LED manufacturers such as Foshan NationStar Optoelectronics Co and HC Semitek Corp, which are expanding their line of lighting for plants and developing new products.

Worldwide, sales of LED plant lighting equipment are expected to grow to $1.85 billion this year. Between 2021 and 2026, the annual compound growth rate of the sector is predicted to reach 13 percent, according to global market intelligence provider TrendForce.

"Urban agriculture and balcony agriculture are important ways for urbanites to ease anxiety. Balcony gardening has an irreplaceable role in horticultural therapy," said Han Yijun, director of the National Agriculture Research Center at China Agricultural University.

Fujing Holdings Co Ltd, the largest retail seller of potted vegetable plants in Shandong province, has seen strong sales in the past few years. The company now plans to go public in Hong Kong, according to the company's prospectus. Fujing has three manufacturing bases in Laixi, Shandong province; Xi'an, Shaanxi province; and Dalian, Liaoning province.

In 2012, Fujing started selling potted vegetable plants in Laixi. The business was profitable－spending on vegetables grown in pots at home generates more income for retailers than a corresponding amount of vegetables sold at markets.

Last year, the company achieved sales of 155 million yuan ($23 million). From 2019 to 2021, its gross profit margin ranged between 45 and 50 percent.