And now he is an advocate for change.
In July, he cohosted the 13th annual Rooted in Community national youth summit in Philadelphia, a convention that drew 150 young people from across the country to write the first Youth Food Bill of Rights.
The document, still a work in progress, states that young people want nutrition education in and outside of school and easier access to produce grown within 100 miles of the city.
It seeks an end to the mistreatment of workers, farmers, animals, and the environment; a ban on high-fructose corn syrup and on the use of pesticides, chemical additives, and genetically modified organisms; support for small, local farms that grow organically; and a restructuring of the currently complicated process of obtaining organic certification.
Johnson held his own when speaking about the bill before a roomful of seasoned adult food activists on Food Day, Oct. 24. And he hopes to join other West Philadelphia students to lobby congressional leaders so the principles in the Youth Food Bill of Rights can be incorporated into the 2012 federal Farm Bill.
"When I was younger, mostly we didn't have money, so we bought cheap food. If you have a low income you've got to go with the best price."
"My grandfather used to help us out a lot. He was the kind of grandfather that you'd be scared of, but at the same time you could count on him. My mother would call him and he'd show up with food, no questions asked."
His grandfather, who had diabetes and high blood pressure, died recently of a heart attack, and Johnson feels the loss acutely.
Johnson's introduction to fresh food and the insidious politics that seem to block equal access to whole, unadulterated food came in ninth grade, when he stumbled upon a meeting in school of the Agatston Urban Nutrition Initiative (UNI), a community outreach program of the Netter Center for Community Partnerships at the University of Pennsylvania.
Founded more than a decade ago to work with people of all ages, the initiative intensified its focus on high school students about five years ago, says staffer Ty Holmberg.
From a core of 30 students the first year, participation grew by 2011 to 75 during the school year and 120 in summer, Holmberg says. UNI now has four school-based gardens where students plant and harvest vegetables they then sell at market stands or cook for themselves and others.
Holmberg says opportunity and incentive were key to the program's growth.
"Students are intrinsically drawn to watching seeds grow," he says. And because they are paid minimum wage for their work in the gardens, they don't have to look for after-school jobs.
At first, Johnson says, he just saw some young people in a room at school, talking and laughing - apparently with no adults around. That alone was intriguing.
One day, a girl from the group approached him. She was pretty, but that's beside the point. Johnson was impressed with her confidence.
"She knew herself," he says. "She straight-out asked me: 'What are you doing with your life?' "
The girl, who turned out to be an Urban Nutrition Initiative youth leader, invited Johnson into the meeting, where he listened and learned: about the abundance of corner stores in his neighborhoods and the absence of supermarkets; snack and soda manufacturers targeting their ads to young people; about what was really in processed foods he has since given up.
No more gelatin desserts, he says, now that he knows they're made with horses' hooves. He buys organic greens when he can. And soda and chips are out.
He started volunteering at the group's onsite farm and at the end of ninth grade he joined UNI.
"After ninth grade, everything about me just skyrocketed," he says. "Joining UNI really opened doors for me."
"I was never one for violence anyway - my mom was always trying to guide me on the right road. But in middle school I had to defend myself there from time to time."
High school might have been a continuation of that struggle, if not for UNI, he says.
"The people I met there" through UNI "were so much fun. They were funny and upbeat and inspiring."
During his four years with the program he learned carpentry, gardening, and cooking - and picked up leadership skills as well.
Through UNI, Johnson spent six weeks at a summer Farm and Wilderness camp in Vermont and attended conferences with young people from Kentucky, New York, and Maryland. The program has an academic component too, and now that he has graduated Johnson is getting help planning his future.
"I love working with my hands, so maybe something in culinary work," he says, adding that he might apply to the Restaurant School at Walnut Hill College and the Art Institute of Philadelphia.
Johnson was on hand Oct. 27 when the Urban Nutrition Initiative broke ground on its fifth garden, on the grounds of Bartram's Garden at 54th Street and Lindbergh Boulevard. Students from UNI served pumpkin soup (see accompanying recipe) and spicy greens, made with ingredients they grew. Johnson poured hot cider for guests.
UNI will pay 12 Bartram High School students to plant, grow, harvest, and sell produce at this new farm. The idea is in sync with Bartram's Garden's long-term plan to create an orchard on-site and engage neighbors in healthy cooking opportunities.
For now, Johnson continues urban gardening as an alum with UNI. This year he hopes to travel again with the Berkeley, Calif.-based Rooted in Community and other West Philadelphia UNI students getting other young people to sign on to the Youth Food Bill of Rights.
"We're calling it our Freedom Ride," he said, smiling proudly.
In August, just after the Youth Food Bill of Rights was drafted, a busload from Rooted in Community took a 12-day Food and Freedom Ride from Birmingham, Ala., to Detroit to talk about food injustices and the benefits of eating locally grown foods - and to commemorate the 50th anniversary of the civil-rights era Freedom Rides, when activists rode buses throughout the South to challenge racial segregation.
Johnson hopes more journeys like that introduce young people and adults to the need for a healthier food system.
"We're doing this because youth are the target of the big marketing corporations pushing junk food. We have the power to fight them."
Makes 6 to 8 servings
2 cups of chopped pumpkin or squash (Hubbard, butternut, and kabocha squash all work well)
1 large onion
1 tablespoon curry powder
2 teaspoons ground ginger
1 teaspoon red pepper flakes
2 cloves garlic, peeled and diced
1 can (13.5 ounces) unsweetened, lowfat coconut milk
Salt to taste
1. Wash the squash, then peel and chop into quarter-inch pieces.
2. Dice onion and saute over medium heat in a nonstick pan for about two minutes, adding a splash of vegetable oil if necessary.
3. Transfer to larger pan or Dutch oven. Add the squash and spices and cook, stirring occasionally, for five minutes. Add garlic. Cook a few more minutes, then add the coconut milk.
4. Let the soup simmer for at least 20 minutes over medium heat or until the squash pieces are soft.
5. Cool the soup slightly, then puree until utterly smooth, using an immersion blender. Or, working carefully in small batches, puree using a potato masher or a standard blender. Add room-temperature water, one tablespoon at a time, if the mixture is too thick.
6. Return the soup to the pot to reheat. Add salt to taste. Serve warm, with whole-grain bread or rolls.
- From the Urban Nutrition Initiative
Per serving: 133 calories, 1.9 grams protein, 9 grams carbohydrates, 4.1 grams sugar, 11.2 grams fat, 0 milligrams cholesterol, 11 milligrams sodium, 3.0 grams dietary fiber.
Contact staff writer Dianna Marder at 215-854-4211, email@example.com, or @marderd on Twitter. Read her recent work at http://go.philly.com/diannamarder