Nasa scientists grew corn seeds in space and found something strange: How microgravity confused roots & shoots that normally know exactly which way to grow

What happens when a plant seed tries to grow without gravity telling its roots which way is down and its shoots which way is up? Nasa has been exploring that question for decades, including through an early 1990s space shuttle experiment involving corn seeds.

Researchers allowed dry corn kernels to germinate in orbit for five days and compared the seedlings with plants grown under normal gravity on Earth. The space-grown corn developed healthy-looking tissues, but its roots and shoots behaved very differently. Without gravity providing a clear directional cue, they lost their usual orientation and grew in less predictable directions.

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The experiment offered an important insight into how plants respond to microgravity. It also raised a bigger question for future space exploration: if astronauts are eventually expected to grow food during long missions, how can plants be helped to thrive when one of their most important environmental signals is missing?

What happened to corn seeds in space?

In the experiment, researchers soaked dry corn kernels and allowed them to germinate aboard the space shuttle. The seedlings were grown for five days in darkness and then compared with similar corn seedlings grown on Earth under normal gravity.

The researchers found that the space-grown plants were broadly normal in terms of their weight, hormone levels and tissue structure. The major difference was their orientation.

On Earth, a corn seedling normally develops with its roots growing downwards and its shoot moving upwards. In microgravity, that clear pattern was disrupted. The roots and shoots grew in different directions instead of following the familiar up-and-down arrangement.

This showed that gravity was not essential for the plant tissue itself to develop over the short experimental period. Instead, gravity appeared to play a major role in telling the growing plant which direction to take.

Why do plants need gravity to know which way to grow?

Gravity acts as an important directional signal for plants. A growing root generally responds by moving towards the direction of gravity, while the shoot grows in the opposite direction.

This process is known as gravitropism. Special cells in plants can detect changes in gravity and help trigger growth responses that orient the roots and shoots.

Take gravity away and that signal becomes much weaker or disappears altogether. Plants can still respond to other environmental cues, including light and moisture, but they no longer have the same straightforward gravitational reference.

That is why the corn seedlings in orbit could continue growing while appearing directionally confused. Their cells and tissues were developing, but the plant had lost one of its key guides for deciding where to grow.

Did the corn seedlings grow normally in space?

Not entirely. The seedlings remained healthy-looking during the five-day experiment, but their growth direction was markedly different from that of plants grown on Earth.

The researchers were also careful about the limits of the findings. Five days in microgravity cannot tell scientists exactly how a plant would behave after weeks or months in space.

That distinction is important because future missions to the Moon or Mars could expose crops to very different conditions for much longer periods. A plant that manages to develop normally for several days may respond differently during an extended growing cycle.

Do other plants lose their sense of direction in space?

Corn is not the only plant to show unusual growth patterns in microgravity. Nasa and other researchers have also studied Arabidopsis thaliana, a small flowering plant from the mustard family that is widely used in space biology research.

Experiments on the International Space Station have found that Arabidopsis roots can show unusual 'skewing' and curved growth patterns in space. Scientists have been investigating the genes and cellular mechanisms behind this behaviour to understand how plants reorganise their growth when gravity is no longer providing a reliable reference.

Other experiments have also shown that light can become particularly important in space. Research has found differences in gene activity in Arabidopsis depending on whether plants were grown in light or darkness, suggesting that plants use several environmental signals to adapt to the spaceflight environment.

Together, these studies suggest that plants do not simply stop growing when gravity disappears. Instead, they adjust their growth systems and rely more heavily on other signals.

How is Nasa preparing to grow food in space?

Growing plants in space is more than an experiment in botany. For future long-duration missions, astronauts could potentially grow fresh food rather than carrying every meal from Earth.

That makes understanding plant behaviour in microgravity increasingly important. Scientists need to know how roots absorb water and nutrients, how shoots develop, how plants respond to light and how their genes change during spaceflight.

Nasa's space biology research infrastructure, including its Open Science Data Repository, brings together data from decades of experiments involving plants and other biological systems in space. Such research can help scientists compare results across different missions and plant species.

Growing plants in space

A few confused corn roots may seem like a small discovery, but the underlying question is much bigger. If humans are going to spend months or years travelling beyond Earth, reliable food production could become an important part of future life-support systems.

The corn experiment showed that plants can continue developing in microgravity, but they lose the strong directional signal that gravity provides on Earth. Future research will need to determine how plants can compensate for that missing cue over much longer periods.

Scientists could eventually use carefully controlled lighting, growth systems or other biological approaches to help crops grow efficiently in space. Before astronauts can depend on a space garden for fresh food, researchers first need to understand how that garden behaves when Earth’s gravity is no longer calling the shots.