In the video, filmed in December, we see inmates at San Quentin building five raised beds for vegetables in the prison yard of the medium security unit. The inmate Charles' excitement about the prospect of a homegrown tomato is pretty palpable. It's the first vegetable garden inside a California state prison.

Planting Justice helped oversee the garden project in partnership with Insight Garden Program, which has been helping inmates at San Quentin rehabilitate and get training in flower gardening since 2003.

Those gardening skills are being put to use once the men leave San Quentin as well. In the past three years, Planting Justice has hired 10 former inmates to work on landscaping jobs, according to the group's website. They get an entry-level wage of $17.50 per hour.

According to the Pew Charitable Trusts, more than four in 10 offenders return to prison within three yeas. By contrast, Planting Justice says the recidivism rate for the men who go through the garden program is 10 percent. Programs in other states have had similar successes — apparently, gardening behind bars seems to help people steer clear of crime once they get out.

In 2012, Nourishing the Planet, a blog of the Worldwatch Institute, put together this list of five urban garden prison projects. It notes that not only do the garden programs help with rehabilitation, they also often save states and local government thousands of dollars.

And one prison garden in Missouri was reportedly so bountiful, it had extra produce — 163 tons' worth — to donate to food pantries, shelters, churches, nursing homes and schools in 2013.

Copyright 2014 NPR.

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Prison Gardens Help Inmates Grow Their Own Food — And Skills