As well as suggesting the 2500 seeds were unaffected by "space fatigue", the early findings indicate that Australian natives, including our floral emblem, the golden wattle, could be tough enough to be cultivated on a space station or on another planet.

The US, Russia and China have sent vegetable seeds and grains into space, with mixed results.

The collection of vacuum-packed seeds, including the golden wattle, flannel flowers, wollemi pine and waratah, were taken into space in May last year by NASA astronaut Gregory Chamitoff.

Since returning in November, three species have passed the germination test and are now month-old seedlings at Sydney's Botanic Gardens — despite orbiting Earth once every 90 minutes at a speed of 28,000 km/h and being constantly exposed to micro-gravity and low-level ionising radiation. The wollemi seeds need to be chilled before they germinate, so will be planted in coming weeks.

Dr Chamitoff said the idea was to look at the possibility of taking seeds off the planet, to protect species from disasters or environmental change on Earth.

"We're looking to see if they are still able to germinate and grow properly when they came back to Earth," he said. "And so far it looks good."

He said plant use on potential planet colonies was also being considered.