"The Martian" is about an astronaut who gets stranded on Mars and has to figure out how to survive before NASA can rescue him. How realistic is the movie's depiction of what life would be like on Mars? The Post's Rachel Feltman fact-checks the movie trailer. (Rachel Feltman and Nicki DeMarco/The Washington Post)

(Warning: The following contains spoilers for the film “The Martian.”)

Ridley Scott’s latest space movie, “The Martian,” is long on drama but short on romance, except for the moment astronaut Mark Watney, played by Matt Damon, sees the object of his desire. “Hey, there” he croons softly — to a wild seedling. This may be the only time in film history that the recipient of pillow talk is a weed, but Watney, you have to understand, is not just an astronaut, he’s also a botanist.

He is marooned on Mars, and the only way he can survive long enough to be rescued is to take a leaf out of Granddad’s book and grow your own. For half a century, we thought space travel had to do with leading-edge technology, cool gadgets and something called telemetry, but no, it’s all about planting tubers.

This is heartening to all the gardening moviegoers out there, who haven’t had a good laugh watching plant drama since “The Little Shop of Horrors,” although the floral inventions in “Avatar” were quite spellbinding, I’ll admit.

Watney corrects this cinematic drought by resorting to growing one terrestrial species in abundance. He raises potatoes. Lots of potatoes. If “The Martian” had a subtitle, it would be “Spuds in Space.”

The movie is set in the future, but this potato fixation seems to be stuck in 1952. Hasn’t Mark heard of the farm-to-table movement, the local food web, Michelle Obama?

Potatoes have great nutritional value, but if I were the one marooned up there, I’d want to mix it up a bit. Though not explicitly stated in the movie, it seems that our hero turned to potatoes because they were in the larder waiting to be cooked. Had he forgotten to bring his bag of seeds? Some botanist. My Martian seed bag would be full of nutty arugula, Tuscan kale, mesclun mixes, beefsteak tomatoes, haricots verts and — to keep those infections at bay — a nice heirloom garlic variety.

You could get microgreens from seed to plate in under three weeks, cutting-lettuce in four weeks and collard greens in about five, but Mark is stuck with the long-haul tater.

At Space Station Idaho, he rigs up a greenhouse of plastic sheeting, fills the floor with the native dirt of the red planet and gets about the business of cutting his potatoes. He figures out how to provide the three things these spuds need — water, light and nutrients. When he finally digs them up, they’re so big the urge is to rip off your 3-D glasses.

Matt Damon in "The Martian." (Giles Keyte/20th Century Fox via Associated Press)

That harvest must have taken months (we’re not quite sure because days on Mars are called Sols), but anyway the yield would have made a homesteader proud. He survived while awaiting his bounty by eating packaged astronaut nosh.

Mark Watney grows the plants so well that even horticulturists are feeling the dramatic lull. There are no potato beetles, blight diseases, leaf hoppers or flea beetles. A third of the way into the movie, you reach an inescapable conclusion: I gotta get me a community plot on Mars.

Mercifully, things go quickly awry.

Growing food in space takes all the acting talents of a Hollywood star such as Damon to make it compelling, but the movie and its mother book contain a solid truth: Space travelers will have to figure out some sort of sustainable farming to make it work. The news this week of seasonal water — possibly — on Mars seems to make this cosmic cultivation more than a pipe dream.

Real astronauts have already grown their own greens — that’s greens, Mark — on the International Space Station. In August, they sampled their own red leaf lettuce grown without the benefit of gravity. (You have to orient the seeds and grow them in an enclosed “pillow” to keep soil, water and nutrients in place.)

An earlier batch grown on the space station was not eaten but returned to Earth to make sure it contained no nasty microbes. This would be highly desirable before eating Mark’s spuds, because the nutrients he used were the dried fecal leavings of his space station colleagues.

NASA gives its audience on Earth a glimpse of lettuce grown in the first vegetable garden in space. (NASA: Space Station Live)

But we’re being churlish (spoiler alert): His horticulture kept him alive, even if the months left him with a scruffy beard, skin sores and the idea that he was a pirate of sorts. Maybe he should have taken an oatmeal bath, but he seems to have saved the oatmeal for a momentous Martian meal. It’s there on the plate, next to the potato.

The Martian PG-13. At area theaters. Contains strong profanity, injury images and brief nudity. 141 minutes.