A plant from Aotearoa with an extraordinary question to answer
Imagine you are helping design a greenhouse for a future settlement on Mars. Every plant must earn its place. Water, energy, growing space and nutrients will be precious resources. Astronauts will need food that is nutritious, reliable and practical to grow. Would you choose a plant that already knows how to survive challenging conditions on Earth?
Kōkihi (Tetragonia tetragonioides), also known as New Zealand spinach is a great candidate.
Kōkihi is an edible coastal plant indigenous to Aotearoa New Zealand. It has fleshy green leaves, a spreading growth habit and a remarkable ability to tolerate conditions that many familiar vegetables find difficult. But could it be useful in space? That’s a question worth investigating.
1. Meet kōkihi
Unlike conventional spinach (Spinacia oleracea), kōkihi belongs to the Aizoaceae family. It grows naturally in coastal environments, where plants may experience salty soils, drying winds, variable rainfall and strong sunlight. Kōkihi has several characteristics that make it an interesting candidate for investigation:
- Salt tolerance: It can grow in conditions containing more salt than many conventional vegetables tolerate.
- Water-stress tolerance: Its fleshy leaves help it manage water, although it still needs water to grow.
- Edible leaves: Young leaves and shoots can be harvested and cooked as a leafy vegetable.
- Spreading growth: It can produce substantial leafy growth, potentially allowing repeated harvests under suitable conditions.
- Cultural connections: It is part of Aotearoa’s botanical heritage and has a history of use as food.
Kōkihi also occurs naturally outside New Zealand, including in Australia and parts of East Asia. This makes it an interesting plant for international scientific collaboration.
However, surviving difficult conditions on Earth does not automatically make a plant suitable for space. That’s where your investigation begins.
2. Why might kōkihi be useful in space?
Nutrition: What would astronauts gain?
Astronauts need a balanced diet containing sufficient energy, protein, vitamins and minerals. Leafy vegetables can contribute important micronutrients and dietary variety. Kōkihi could potentially provide fresh greens to complement stored or processed foods. But before recommending it, scientists would need to investigate its nutritional composition, food safety and how these might change under different growing conditions.
Your research question: How does the nutritional value of kōkihi compare with lettuce, conventional spinach or other leafy vegetables?
Water: Could it use resources efficiently?
Water is one of the most valuable resources in a space habitat. Kōkihi’s ability to tolerate water stress makes it scientifically interesting, but drought tolerance does not necessarily mean high productivity with little water. A plant might survive drought while producing very little food.
Your research question: How much edible food could kōkihi produce for each litre of water used?
Space: How much room would it need?
Space greenhouses will have limited growing areas. Kōkihi naturally spreads across the ground, which might be an advantage in some growing systems but a disadvantage in compact vertical farms. Could it be grown in trays, trained onto supports or harvested frequently to control its size?
Your research question: How much edible biomass could kōkihi produce per square metre of growing area?
Resilience: Could it cope with unexpected problems?
Future space habitats will depend on carefully controlled environmental systems. But what happens if a pump fails, water becomes temporarily limited or the nutrient solution changes? Plants that tolerate environmental variation may contribute to more resilient food-production systems. Kōkihi’s adaptations could provide useful clues, although they would need to be tested in controlled conditions.
Your research question: Which environmental stresses can kōkihi tolerate while continuing to produce edible leaves?
3. There’s more to food than nutrition
Imagine spending two years living in a habitat on Mars. Your meals are nutritious, but much of your food comes from packets.
Then someone brings you a freshly harvested vegetable. You can see its colour, smell it, prepare it and share it with your companions. Growing plants in space is not only about producing calories. Fresh food, familiar flavours, gardening and caring for living things may contribute to crew wellbeing.
For astronauts from Aotearoa, growing a familiar native edible plant could also provide a connection to home.
Your research question: Could culturally familiar plants contribute to astronauts’ psychological wellbeing during long-duration missions?
4. What might make kōkihi a poor choice?
Good science means looking for reasons your favourite idea might be wrong. Kōkihi presents several questions that need investigating. Its spreading growth habit might require more space than other vegetables. Its edible yield, growing time and nutritional value would need to be compared with established space-crop candidates.
Like conventional spinach, kōkihi contains oxalates, compounds that can affect mineral availability and require consideration when evaluating it as a regular food source. Its salt tolerance also raises an interesting question: if grown in saline conditions, could salt accumulate in its edible tissues? And we do not yet know whether kōkihi would perform well in the specific lighting, atmospheric and cultivation conditions of a space habitat.
Your challenge: Identify at least three disadvantages of growing kōkihi in space. How could scientists investigate them?
5. Design your own space-growing experiment
You don’t need a spacecraft to begin investigating a space-agriculture question. Imagine growing kōkihi alongside conventional spinach or lettuce in identical containers. You could investigate how the plants respond to different watering schedules, light conditions or growing media. Measure their growth, record observations and compare results.
For example:
Research question: Does kōkihi maintain growth better than conventional spinach when water availability is reduced?
Hypothesis: Kōkihi will maintain a greater proportion of its growth under reduced watering because it is adapted to environments where water availability can vary.
What could you measure? Plant height, leaf number, leaf area, fresh biomass and water consumption.
What would make the experiment fair? Similar starting plant sizes, consistent growing conditions and repeated trials.
Remember that an experiment on Earth cannot reproduce all the conditions experienced by plants in space. It can, however, help answer important questions about their biology.
6. The bigger question: What should we take from Earth?
Kōkihi illustrates something fascinating about astrobiology. Earth contains an extraordinary diversity of plants that have evolved ways to survive heat, cold, drought, salt, flooding and nutrient-poor environments. Some are crops. Others are plants we rarely notice. Even plants commonly dismissed as weeds may possess adaptations worth studying. Could these biological survival strategies help us develop more resilient food systems, both on Earth and beyond? And if we eventually establish human habitats on other worlds, which parts of Earth’s biodiversity should accompany us?
These questions connect space agriculture with ecology, genetics, conservation and planetary protection.
7. Your turn: What would YOU grow?
Kōkihi is only one example.
You might investigate kūmara, potatoes, beans, strawberries, mushrooms, herbs or an entirely different organism. Perhaps you know a plant that grows in difficult conditions near your home. Perhaps your family grows a vegetable with special cultural significance. Perhaps you have an idea nobody has considered.
For the JAXA Space Harvest Ideathon, your task is to investigate your chosen plant and explain why it could be valuable to future space explorers.
Consider its nutritional benefits, resource requirements, resilience, cultural significance and contribution to quality of life.
Most importantly, support your ideas with evidence.
You don’t have to choose kōkihi. In fact, we hope you’ll surprise us with something different.
The next great idea for growing food in space might already be growing in your garden.
Ready to investigate?
Join the Space Harvest Ideathon 2026–27
The New Zealand Astrobiology Network coordinates New Zealand participation in this international educational initiative organised through JAXA’s Kibo-ABC programme.