Back at the beginning of December, I mentioned that astronauts on the International Space Station (ISS) were hoping to have flowers in bloom for the new year. After successfully growing a second crop of lettuce in the Veggie growing system on board, they were trying their hand at something more complicated. Coaxing a plant into flowering in space has been done before, but it’s trickier than just growing leaves – but it’s something we’re going to have to crack if we want to be space farmers. We need flowers before we can grow fruits and grains, and we also need to be able to produce seeds in space if living away from the Earth is to be sustainable.

In the absence of gravity, getting water to stay in the right place – around the root zone – is a problem. In the first Veggie lettuce experiment, two plants were lost to drought. In the second, one ‘pillow’ failed to produce a crop. With the zinnias, water partially engulfed three of the plants. They began to show guttation – where water drips from the end of leaves, due to high water pressure inside the plant. You can see guttation in well-watered plants on Earth, usually first thing in the morning. It’s not an issue in an environment where the water can just drip off and drain away. But on the ISS the plant leaves started to bend down and curl – this is epinasty, and can be a sign of waterlogged roots.

Scientists on the ground determined that the problem was a lack of air flow, and that the fan in the Veggie unit should be turned up. But an unexpected space walk to fix a technical problem intervened, and it was a few days before the unit could be adjusted.


By 27th December, the news wasn’t good, with astronaut Scott Kelly reporting that the zinnia plants that had been doing so well were dying from mould (mold, if you’re American!).

He removed the mouldy leaves and froze them, to be returned to Earth for scientific analysis. The plants and Veggie were sanitized. Two plants died, but with the fans turned up the remaining plants returned to healthy growth. NASA has pointed out that dealing with the problems has been a valuable research opportunity. And Scott Kelly has been promoted to Veggie “Commander”, with more autonomy to adjust the growing conditions – something both the ground scientists and the astronauts are happy about! He has been given “The Zinnia Care Guide for the On-Orbit Gardener”, a basic guideline to growing these plants, and under his care they are blooming!


Although, as previously discussed, these aren’t the first flowers to bloom in space. There have been quite a few, really, although possibly none of them was as pretty 😉


The zinnia flowers on the space station are being grown to study, not to eat*, but it turns out that the petals are edible. So if you’re planting a space-themed garden this year you can tuck into your zinnias if you want to! Some recipes are available from Food on Fifth, and Arcadia Farms have shared 10 ways to eat zinnias.

[*The astronauts wouldn’t have been allowed to eat this crop anyway, following the disease problems.]

So what’s next for Veggie? The Veg-03 experiment will include two sets of Chinese cabbage and another of red romaine lettuce, and will start later this year. Dwarf tomatoes are scheduled for 2018.



Grow your own space zinnias

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