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What Do Plants Do At Night?

plant at night with the moon in the background

Plants are amazing because they look beautiful, take in carbon dioxide, and respire. Most people don’t know much about them or how they work. Still, others wonder what plants do at night, especially when they are houseplants, and there is a concern about health.

The truth is, plants get up to quite a lot at night and you’ll be surprised to hear that it involves maths, yes you read that right, maths. Primarily though, their nightly activities mainly revolve around food, but I’ve done the research and put together everything you need to know about what plants do at night. Check it out below.

Do Plants Respire (Breathe) At Night?

Every living thing uses respiration to get the energy it needs to stay alive. Cellular respiration is what plants do. This allows them to convert any nutrients it obtains from the soil into energy that will fuel its cellular activities and needs.

Most people confuse cellular respiration with photosynthesis, which is the process where sunlight is converted into a chemical energy that is stored as glucose. This is then later used for respiration. Photosynthesis is essential for cellular respiration to happen.

During respiration, the plants consume the nutrients they need to keep their cells alive, slow growers tend to use a little less. During photosynthesis, the plant creates its own food.

For respiration, the plant needs glucose and oxygen and releases heat energy, water, and carbon dioxide. For photosynthesis, the plant takes in carbon dioxide, light energy, and water to produce glucose and oxygen.

Photosynthesis only happens during the daytime when there is enough sunlight. However, plants can respire at all times of the day and night, even though their stomata close at night.

How Do Plants Respire At Night If Their Stomata Are Closed?

Well, first of all, not all plants have their stomata closed at night and some don’t leave them closed all night. However, even when the stomata are “closed” oxygen respiration is not fully blocked. It’s simply restricted. So the plant is unable to take in quite as much oxygen as it would typically in daylight hours, but it can still respire.

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Do Plants Release Carbon Dioxide At Night?

When it is dark outside, the plant only consumes oxygen and releases carbon dioxide. During dim sunlight, the photosynthesis rate is the same as the respiration rate. Plants absorb the oxygen they create through photosynthesis and also uses up all the carbon dioxide it forms through respiration. Therefore, no gas exchange takes place, but if you’re wondering which plants release more oxygen then check out my guide here.

During bright sunlight, photosynthesis uses the carbon dioxide and makes too much oxygen for the plant. Therefore, more oxygen is released into the air. Any unused glucose is stored inside the plant to use later, such as at night, when it can’t produce it through photosynthesis.

Do Plants Know It’s Night Time?

Plants don’t have a central nervous system or brain with all the neurological processes like humans. Therefore, they don’t sleep like we do. Still, plants are aware of the different times of day because they have circadian rhythms that are tuned to the cycles of darkness and night. Just like animals and humans, they do things differently at night than in the daytime.

You’ve learned that plants make food in the daytime through photosynthesis. At night, this can’t happen because it requires light to start the process. Still, plants don’t just sit around in the dark waiting for the sun to come back up.

No, they still respire, which, for them, is a combination of breathing and eating. Respiration combines the food they created with oxygen to make energy that they use to grow. During the day, they create special sugars, and at night, the glucose moves around to the different areas of the plant. It goes specifically to those areas that were burned or overused for growing from the night before.

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In a sense, plants make food in the daytime and eat it all at night.

Because eating requires oxygen, plants do consume some oxygen at night. What they take in is trivial compared to how much oxygen humans need and how much they produce during the daytime.

Do Plants Drink At Night?

Often I’ve wondered whether I should water my plants at night. So it got me wondering, do plants drink at night?

Most plants do drink at night but they consume much less than they do in the day. There’s less evaporation of water through the night as the temperatures tend to be lower. Therefore, watering your plants at night is not advised as it will just saturate your roots, potentially causing root rot.

blackboard with maths on it, plants do math at night

Plants Do Math

Yes, it sounds a little silly, doesn’t it? Plants don’t have brains, so how can they do math? Well, they might not do it like humans do, but they do have to calculate how much food they can safely eat before the next sun-up.

Their chemical calculator tells them how much energy they stored that day and divides that amount by how long the night might be. Therefore, they can use portion control to ensure that they don’t run out of energy before the next day.

This little-known fact was discovered by biologists from the England John Innes Centre. They found out that plants do have a biological process, allowing them to divide up their stored energy. This means plants don’t have a problem with portioning out their reserves at night, ensuring that they can continue to grow.

You know that plants make the food during the day and burn it off at night. Their calculations are extremely precise, as well. Plants won’t starve themselves by using all their energy at once, and they can make more efficient use of the food they do have.

The issue is that if the plants use their food too quickly, they won’t grow and could starve or die. However, the second part of that is that if they use their stored food too slowly, they waste it.

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These biologists used experiments to determine how the plants calculated their food needs. In a sense, they gave the plants a little math quiz. Here, they had plants that were used to 12-hour nights and days. Then, they shut off the lights early one day after only eight hours. This forced the plants to adjust their night rhythm. Because the plants couldn’t store as much food that day, they recalculated their metabolism.

Even with that trickery, the plants aced the exam. The next morning, they had just a small amount of food left over. They didn’t starve or store too much food.

How Do Plants Do Math?

The plants didn’t have to do anything consciously. The chemical reactions within their cells did the crunching of the numbers automatically. You can plainly see here that plants are incredible. They do so much for the world around them, but they’re also quite smart! If you’re not too great at crunching numbers yourself, I’ve put together a list of affordable houseplants, check it out here.


We hope that you have learned a little bit more about plants and what they can do. The age-old question of what do plants do at night has been answered, but if you’re still curious then why not check out our information on why they need darkness. You now know that they aren’t just like humans and animals, but they do have a period where they don’t do as much, similar to when humans and animals sleep.

Just like us, they have a trigger to know when to produce food and when to use it. Though they don’t go to the store or out to eat, they can move about a little to make sure they are fully exposed to sunlight. Before bed tonight, you may just want to wish your houseplants ‘goodnight’ before going to bed yourself!

Why Do Plants Grow Taller In The Dark? – Fallsgardencafe

Thursday 24th of February 2022

[…] You’ve learned that plants make food in the daytime through photosynthesis. At night, this can’t happen because it requires light to start the process. In a sense, plants make food in the daytime and eat it all at night. Because eating requires oxygen, plants do consume some oxygen at night. via […]


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