An extraordinary kind of garden is starting to bloom, and it is miles and miles away from Earth—in outer space.

The National Aeronautics and Space Administration (NASA) recently managed to grow a zinnia flower aboard the International Space Station, fuelling hopes that mankind will soon be able to grow plants in outer space for sustenance.

NASA astronaut Scott Kelly tended to the plant and helped it bloom under the space agency's Veggie Programme, which seeks to find ways to grow plants in space.

He proudly announced this milestone on Twitter a few days ago.

"Yes, there are other life forms in space! #SpaceFlower #YearInSpace," Kelly said in a tweet last Jan. 16, with a picture of the zinnia flower attached to it.

The astronaut was given full autonomy last month to grow the zinnia flower, independently calling the shots on when to water the plant instead of waiting for instructions from Earth.

This was done after the project encountered difficulties, including the plant receiving excessive water, experiencing over-drying and suffering from a kind of mould that had NASA stumped.

Trent Smith, Veggie project manager, said in a statement that the blooming of the zinnia flower in the space station is an important milestone, since the plant is quite hard to grow.

"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," Smith said, as quoted by Space.com.

NASA is now looking at growing other flowering plants that can yield food for astronauts over on long journeys, the official added.

Earlier this year, the NASA also successfully grew romaine lettuce in the space station. Astronauts were even able to snack on the newly grown plant.

Back in 2012, the space agency was also able to propagate sunflowers in outer space.