On Mars there’s no atmosphere and no magnetic field, so if you just put a plant on the surface they’ll die. So, you need to grow them underground in a mostly earth-like atmosphere at mostly earth-like pressure lit by artificial lights.

you can put algae in a plastic bag and grow them in there, so they're in a pressurized container so there's enough air pressure in there for them.

sth like this: link to post

i've actually been thinking about this exact problem, and you don't actually need to grow wheat on mars. you only need calories, protein, fats, vitamins, fiber. you can get calories and protein from algae (which you can grow in small plastic tubes/boxes). Spirulina (bacteria type) is a typical candidate for that.

It's especially protein-rich. Growing it would require less than 1000 m² per person, i think, though i'm not sure.

growing salad for vitamins and fiber takes significantly less area (maximum 50 m² per person) and can be done indoors, wherever you live.