How do astronauts grow plants in space?

Space farm.
Space farm.
Image: NASA
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In August 2015, astronauts on the International Space Station ate the first vegetables grown in space; earlier this month, they coaxed the first zinnias to bloom.

Though space agricultural technology hasn’t quite reached the level of that seen in The Martian, overcoming the challenges presented by zero-gravity to grow plants was a feat in itself.

Yesterday (Jan. 20), NASA released a video describing the “historic vegetable moment” and explaining the growing process more in-depth. You can watch it here:

Normally, plant roots grow downward, where it’s easy for them to soak up water and nutrients that make their way into the soil. In space, roots grow in every direction, and water and other essential plant foods float.

Two years ago, NASA astronauts Steve Swanson and Rick Mastracchio set up the aptly-named “Veggie” in the ISS. Veggie is a container that gives plants a little more guidance by using ”plant pillows.” These pillows are bags of dirt, fertilizer, and nutrients equipped with wicking material that soaks up water. Astronauts glue seeds onto the wicking material directionally, so that their roots will grow toward the bottom of the bag and the stems will grow outward. LED lights shine above to give the plants the energy they need to grow, and expandable plastic walls provide protection for the leaves as they get taller.

So far, astronauts have just grown red romaine lettuce, but in the future, they will grow cabbage and tomatoes with seeds from the next SpaceX delivery.