Kenyans have been given a special holiday to plant 100 million trees as part of the government's goal to plant 15 billion trees in 10 years, reports the BBC.
The holiday allows "each and every Kenyan to own the initiative", according to Environment Minister Soipan Tuya.
Each Kenyan is being encouraged to plant at least two seedlings, leading to the 100-million target.
The initiative is intended to help fight climate change.
Trees help tackle global warming by absorbing carbon dioxide from the air while releasing oxygen into the atmosphere.
The government is making available about 150 million seedlings in public nurseries.
It is providing the seedlings for free at its forest agency centres for Kenyans to plant in designated public areas.
But it has also encouraged Kenyans to buy at least two seedlings to plant on their own land.
President William Ruto led the exercise in Makueni in the east of the country. Cabinet ministers were sent to other regions to lead the process alongside county governors and other officials.
At one site near the source of Kenya's second-longest river, Athi, there were dozens of people, including soldiers and residents, some with their families.
"I have come together with my colleagues, I'm happy to be here to show my love for the environment," student Wycliffe Kamau told the BBC.