Scientists are studying flowers that can bloom at the peak of summer when Tokyo hosts the Olympics and Paralympics in 2020.

Flowers that can withstand the heat of summer have not been the subject of much research. The Tokyo Metropolitan Agriculture and Forestry Research Center, based in Tachikawa, surveyed about 1,200 varieties, selecting about 250.

These will be featured in a handbook that could be completed in January, with an eye toward having the flowers used decoratively during the 2020 Games.

Experiment in Hibiya Park

“Tokyo’s severe heat is a big enemy of vegetation,” said Tatsuo Okazawa, 45, a chief researcher at the center.

“There hasn’t been much research on summertime flowers, and there’s very little production of them,” he said.

The 2020 Games are scheduled to take place at the height of summer, from late July to early September. Immediately after Tokyo won its Olympic bid, the center started researching flowers that dependably bloom in summer.

Working with Tokyo flower producers and others, they planted a variety of seedlings in Hibiya Park in Chiyoda Ward, Tokyo, in the summers of 2016 and 2017 to determine how well they withstood heat and dryness.

The results showed that sun smile, a morning glory variety, and jolt, a type of carnation, were able to withstand heat well. They also discovered varieties that could be produced by carefully managing water flow and by making other modifications.

Echo of ‘64

The Tokyo agricultural experimental station, a predecessor of the center, researched autumn flowers before the 1964 Olympics. During the Oct. 10 opening ceremony at the National Stadium that year, athlete Yoshinori Sakai carried the torch to the Olympic cauldron up a stairway lined with bosakiku — a yellow chrysanthemum variety bred especially for the games.

At the time, most flowers grown in flowerbeds and elsewhere were spring varieties. The experimental station thus focused on flowers that could grow in autumn. The marathon route on the Koshu Kaido road was lined with potted Indian shot plants and cockscombs, and the city was decorated with sages and zinnias. The fruits of this research carried on after the Olympics, and now flowers are seen in urban areas even in autumn.

“With the Olympics coming back to Tokyo, we later-generation workers would like to make summer flowers our legacy,” Okazawa said.

Future handbook

The center plans to publish a handbook on about 250 varieties of about 25 species it has found to be relatively easy to grow in summer, such as pentas and periwinkle, which are native to tropical regions. The illustrated handbook, which will describe the flowers’ characteristics and how to grow them, might be finished as early as January.

In addition to publishing it online, the center plans to distribute it to plant nurseries, community organizations and others.

”I would be so happy if we could help show off how wonderful Japan and Tokyo are through a diverse array of flowers,” Okazawa said. “I hope the Tokyo Games will be filled with flowers, and that people will grow them at home as well.”