A project to plant 190 kilometres (120 miles) of Japan's tsunami-hit coast with cherry trees has begun, with organisers saying they want something to welcome nuclear evacuees in three decades' time.

Residents, volunteers and those who fled the atomic disaster are set to plant 20,000 cherry tree saplings in Fukushima's coastal Hamadori region over the next 10 years, Jiji Press said.

"Everyone may come back to Fukushima 30 years from now," project leader Yumiko Nishimoto, 59, told Jiji. "We want to leave local communities in a state our children can be proud of."

Large areas of Fukushima were evacuated in the aftermath of the world's worst nuclear accident in a generation, when reactors in Fukushima went into meltdown after the plant was swamped by the 2011 tsunami.

Scientists have warned that some areas may be uninhabitable for decades.

Nishimoto and her husband left their home in the town of Hirono, less than 30 kilometres south of the crippled nuclear plant, but returned in late 2011.

She was inspired to begin the project after seeing television footage of cherry blossoms in an uninhabited evacuation zone in spring 2012, Jiji said.

Mandatory evacuation zones have gradually been lifted as radiation levels have dropped, and the area south of the plant has generally seen moves to repopulate more quickly than other areas.

Cherry blossom has a special place in Japan's national psyche, with the annual blooming of the fragile flowers a chance for friends, family or colleagues to gather under the trees to eat and drink.