“This was not what I thought my first book would be,” admits Stephen Voss . For photographing – and interacting with – bonsai trees couldn’t be farther from his day job. The Washington D.C.-based photographer makes a living by photographing some of the busiest people in the country who have very little time: Alan Greenspan and Michelle Obama to name two. He even photographed Bernie Sanders for the latest TIME cover . But last October he embarked on a personal project that rekindled a 20-year old passion: bonsai trees.

The bonsai collection at the National Arboretum in Washington, DC is regarded as one of the finest outside Japan. And it’s where Voss first encountered the trees, many of which are more than 100 years old. “What I love most about bonsai is the empathy of its practitioners that is reflected in these trees,” says Voss. “Practitioners who care for and maintain trees that will outlive them, that will eventually be watched over by someone else, long after they’re gone.”And as a subject for photography, time was an integral part of the shoot. Just in a very different way. “It was often a waiting game,” explains Voss. Waiting for the perfect cloud to perfectly shade the sun and diffuse perfect light. “In those long hours of slow, almost meditative photography, I remembered some of the things I loved about taking pictures, about the feeling of taking a good, hard look at something and deciding how I should respond to it in a photo.”

Voss is working with his favorite designer to create a beautiful photography book about bonsai and slowing down. He’s titled the book “In Training” and is funding the project on Kickstarter.