The first flower to grow in space had a rocky start to its growth, but it's simply beautiful (and out of this world).

The 13-pedaled orange zinnia is the first flower to be grown in the zero gravity of space aboard the International Space Station.

United States astronaut Scott Kelly tweeted a photo of the plant on Sunday: "#SpaceFlower out in the sun for the first time! #YearInSpace."

According to Trent Smith, project manager of the ISS Veggie facility, the zinnia plant is "more sensitive" to light characteristics and has a longer growth duration of 60 to 80 days - much longer than other plants previously grown in space.

"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," said Smith.

The flower's blooming is a landmark moment in scientific history and a testament to Kelly's hard work in saving the plant after it nearly died.

"Our plants aren't looking too good. Would be a problem on Mars. I'm going to have to channel my inner Mark Watney," tweeted Scott Kelly on December 27, before altering the crop's watering schedule aboard the ISS. Scott Kelly/NASA

Just a few weeks ago, Kelly tweeted a photo showing the plant's leaves covered in mold after the seed containers were leaking and the plants' roots were being flooded, according to NASA: "Our plants aren't looking too good. Would be a problem on Mars," Kelly wrote.

To save the plants, Kelly changed their watering - only spritzing them when water was needed - rather than following a strict hydration schedule.

"If we're going to Mars, and we were growing stuff, we would be responsible for deciding when the stuff needed water," said Kelly.

Some plants ended up dying, and they will be taken back to Earth to be analyzed; meanwhile, the living zinnia crop will continue to be monitored.

The next step in producing organic space food? Tomato seeds could be brought up to the ISS in 2018, according to Engadget.