Among the many challenges of life in space, there’s one that is mostly ignored by TV shows and movies: eating fresh food.

The capability to grow crops in space or in a colony, whether on the Moon or Mars, might be crucial for long-duration missions. And a new paper, published in Botany Letters, shows that we still have a lot to learn to become space farmers.

Lucie Poulet and colleagues from the University of Clermont-Ferrand have published a detailed analysis of what we know and what we are yet to find out about gardening outside Earth.

Since the dawn of the space age, plants have been studied in a microgravity environment. From the early Russian and American tests to the latest experiments on the International Space Station (ISS), we know plants grow in orbit. By controlling the right factors like confinement, radiation, and ventilation, we have found that it is possible to grow plants in a similar way to their Earthling counterparts.

The paper reviews the many studies done on plants in space. It highlights that despite the high number of experiments on plant growth performed in Earth orbit, these remain too small-scale to gather enough information on crop yield in lower gravity environments. 

They also mention several other factors that remain unknown. Microgravity affects cell growth, and seeds produced in space tend to be different to Earth. This could affect the nutritional value of the seed but also the flavor of the space plants.

And growing enough food might be a challenge too. Technologies for large-scale space agriculture are yet to be developed, and constructing them might not be a trivial issue.

“Challenges remain in terms of nutrient delivery, lighting, and ventilation, but also in the choice of plant species and traits to favor,” Poulet wrote in the paper.

“Additionally, significant effort must be made on mechanistic modeling of plant growth to reach a more thorough understanding of the intricate physical, biochemical and morphological phenomena involved if we are to accurately control and predict plant growth and development in a space environment.”

We have years to go before the first deep-space crewed mission, but the task ahead is significant. At the moment, in space, no one can eat your greens.