Go ahead—garden without pesticides. Knock yourself out. Feel free to grow veggies without petroleum-fueled machinery, chemical fertilizers or even experience. Yawn. It's been done. But hey, farmer wannabe, can you garden without a yard?

Marissa Dorais is doing it. The 23-year-old graduate of Lewis & Clark College didn't have a yard, so she built one. Now Dorais grows her veggies in a 3-by-5-foot cart, a "mobile garden" that she wheels every day from the shady parking lot of her apartment to a sunny spot on the sidewalk across the road.

"All that traveling makes the veggies happy," says Dorais. "I think they're definitely more expeditious than your average produce."

You might not think that Dorais could grow all that much in what amounts to an oversized rolling window box. You'd be wrong. Right now she's raising parsnips, parsley, Oregon shelling peas and Walla Walla onions. During peak time in early autumn, she says she'll harvest over 10 pounds of veggies per week.

The cart itself was built in a single day, on the floor of Dorais' studio apartment. With the help of a carpenter friend from L.A., she constructed an open box out of two-by-fours, attached the handle mechanism from a baby stroller bought at a thrift store, and added some wheels to the bottom. All that remained was to fill it with potting soil and attach the head of a hacksawed unicorn to the front—a purple figurehead, like the mermaid on a ship's prow.

So far the mobile garden has raised more than a few eyebrows, but that's no problem for Dorais, who's trying to start a trend. A purple Magic Marker inscription reads, "Please copy, innovate, adapt and spread this design as you wish." And who knows? Maybe the idea will catch on.