On Jan. 16, astronaut Scott Kelly aboard the International Space Station proudly tweeted a photo of "the first flower ever grown in space." While anything the 51-year-old engineer does generally gets love from the social media scene, this photo of a zinnia bloom went viral especially fast.

As Rachel Feltman for the Washington Post points out, Kelly's claim about the "first flower grown in space" isn't technically accurate. Astronauts have previously managed to make plants like lettuce and even sunflowers bloom in microgravity. What makes the zinnia distinct is that it's the first flower grown from start-to-finish during an official NASA mission. As veggie project manager Trent Smith describes in an article on the difficulties of growing plants in space, the zinnia is a bit more sensitive to the environmental challenges of the ISS.

“The zinnia plant is very different from lettuce," he explained. “It is more sensitive to environmental parameters and light characteristics. It has a longer growth duration between 60 and 80 days. Thus, it is a more difficult plant to grow, and allowing it to flower, along with the longer growth duration, makes it a good precursor to a tomato plant."

In growing the zinnia, Kelly ran into all kinds of difficulties — from high humidity to mold. Even the watering schedule became a problem. Eventually, he decided that the only thing left to do was to deviate completely from NASA's instructions.

“You know, I think if we’re going to Mars, and we were growing stuff, we would be responsible for deciding when the stuff needed water," Kelly shared. "Kind of like in my backyard, I look at it and say ‘Oh, maybe I should water the grass today.’ I think this is how this should be handled.”

With the okay from NASA to handle things autonomously, Kelly helped the zinnia rebound and it rewarded the crew with a spectacular bloom.

Kelly's experience as one of the first space farmers will be enormously beneficial to future astronauts who one day grow their own food millions of miles away on Mars.

“All these things are so rich in information, my head kind of spins to think about what to focus on,” added Smith. “This is perfect. This is really getting us down the road for other crops.”

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Space farmers coax zinnia into bloom
As astronaut Scott Kelly discovers, getting anything to bloom in space takes a lot of hard work and patience.