Do Plants Grow At Night? (Facts You Must Know)

Many do not know whether plants grow at night or only during the day when sunlight is available. If you think plants don’t grow at night, the following information can surprise you!

Plants need light to grow, but it does not mean they stop growing when the sun sets. Contrary to numerous beliefs, the plants continue to grow at night at a faster rate. Most plants respire at night without light, using the oxygen and sugar they produce during the day to grow and thrive.

To understand this process clearly, we need to discuss the process of respiration and photosynthesis in greater detail, which I have covered in this article.

Plant growth during the day and at night

Plants grow both day and night, but their growth patterns differ.

If you keep your plants near a light source, you must have noticed that they tend to grow toward the light.

During the day, the plants grow more horizontally towards the light.

This is why plants that enjoy basking in the sun have large glossy leaves, as the larger surface sizes absorb more sunlight.

At night, however, the growth is more vertical.

This is why studies have found more growth in height just before dusk though the differences in growth rate vary from plant to plant.

Do plants grow at night?

The answer to the above question is yes, and plants grow at night.

The energy they consume during the day is used to grow at night.

This is known as the circadian cycle or the 24-hour biological cycle.

Contrary to popular belief, plants neither sleep at night nor do they shut down at night as humans do.

Instead, though they cannot photosynthesize in the absence of sunlight, they continue the process of respiration, where they convert the nutrients into energy to carry on their biological functions.

What do plants do at night time?

So as far as we know, plants grow with the help of sunlight as it makes the plant prepare its food from which it derives the energy.

The chlorophyll cells act like solar panels, which collect and store the energy driven by sunlight.

Chloroplasts are tiny cells in plants that absorb sunlight during photosynthesis and help plants produce energy.

These chloroplasts start to shrink at night as the photosynthesis process stops, after which they release stored energy.

Also, during the night, the buds and flowers close as their primary function is reproduction, carried on by only active pollinators during the day.

Then the plants use this energy from the sun to convert carbon dioxide and water into oxygen and glucose.

This oxygen is then released into the air as a waste product from the plants while the plant uses glucose to grow its foliage and roots and produce flowers and fruits. 

Can plants grow in the dark?

Plants grow in the direction of light when they grow in the shade.

You must have noticed that if you leave something in the garden, the grass around the object grows bigger than the rest of the yard.

This is because the grass around the objects grows in the shade, so they try to reach sunlight by elongating themselves.

However, the same scenario is not if you cover the grass bed entirely with any object for a few days.

Suppose when you grow a raised bed on grass, and you smother the grass with cardboard, etc., the grass beneath starts dying.

This is because plants cannot grow in complete darkness and need sunlight to carry on with the photosynthesis process.

What is the respiration process of plants?

Respiration is the process in which plants use the glucose they have derived during the day through photosynthesis.

Though most people believe that plants do not use oxygen during the day, it is not so.

The fact is that plants use carbon dioxide in more quantity than oxygen during the day, but at night it uses more oxygen and less carbon dioxide.

During respiration, plants release water vapor through a process called transpiration.

It is also a common misconception that plants respire only at night when it respires throughout the day, just like humans breathe all the time.

However, there are slight differences between respiration during the day and at night.

The respiration that occurs at night is called respiration, but respiration during the day is known as photorespiration.

So factually, plants produce oxygen and consume carbon dioxide, which explains why deforestation is linked to rising carbon dioxide levels worldwide.

Plants play a vital role in the environment and humans because we absorb the oxygen they release into the air.

Also read: Why is my indoor plant dripping water?

Photosynthesis vs. Respiration 

Both respiration and photosynthesis are essential processes in our plants that let them make energy and grow healthily.

Photosynthesis is the process in which plants absorb sunlight through their tiny cells’ chloroplast containing chlorophyll that converts the sunlight into energy.

As I have already discussed, carbon dioxide and water are absorbed, which becomes their energy source. 

Since sunlight is unavailable at night, this process only occurs during the day, so photosynthesis does not occur at night.

Now at night, when there is no more light, plants begin the process of respiration, converting this light and water into glucose, giving it the energy to grow.

Plants grow during the process of respiration and not during photosynthesis which is a misconception many of us hold.

So during the day, the plants photosynthesize and respire, but at night, they respire and stop photosynthesis.

Process	Photosynthesis	Respiration
Gas in	Carbon dioxide	Oxygen
Gas out	Oxygen	Carbon dioxide and water vapor
Time	Daytime	Both day and night
Cells	Chloroplasts	Mitochondria

Why do plants need respiration?

Plants need to respire because otherwise, all the nutrients consumed during the day would stay unused.

In the process of respiration, plants can reuse and restore the resources they have gained through photosynthesis necessary for their growth.

During the process, they convert the sugar they have gotten during photosynthesis into energy to fuel their metabolism.

With the help of this, they can produce new leaves, grow taller and stronger, and bear fruits and flowers.

Respiration occurs in the mitochondria of plant cells and does not require light.

Time-lapse photography shows that plants have a striking growth spurt just before dawn.

We will discuss this in the section below.

What time do plants grow? – Plants growth spurts

Plants grow all day and night, but most plants’ fastest growth rate has been seen at night.

The growth of plants at night not just continues but happens at the fastest rate.

During the day, the plant performs several metabolic activities for survival, like carrying out photosynthesis, controlling the temperatures, and keeping itself hydrated.

The plant is free from those duties at night, focusing on its growth and cell repair.

At night the stored energy from the cells activates the growth hormones in the plant.

The stems of the plant elongate the fastest right before dawn.

 A team of scientists from the Salt Institute for Biological Studies, UC, San Diego, and Oregon State University studied the time when plants grow the swiftest.

The study found that when plant stays under shade, they send more growth hormones to elongate the parts of the plant to reach more sunlight.

So they discovered that the plants release growth hormones just before dawn to quicken their growth.

They grow fastest at this point than they do all day.

This is because plants go through a 24-hour cycle around photosynthesis during the day, respiration at night, and a growth spurt at dawn.

Long day vs. short day plants

Many of you may have heard about short-day and long-day plants.

These are terms that describe the amount of sunlight and darkness that is required by plants to grow.

There was a misconception before that the length of the day determines the plant’s growth, but it turned out to be the opposite.

The hours of darkness are the primary factor that results in growth and triggers flowering in the plants.

The plants that are termed short-day plants require darkness of at least 12 hours over several weeks and months to bloom, which is why these plants mainly bloom in winter and spring when the daylight is shorter and nights are longer.

Some short-day plants include kalanchoe, onion, rice, cotton, daisies, sugar cane, chrysanthemums, and poinsettias.

Long-day plants need less than 12 hours of darkness and longer hours of sunlight to flower, so in summers, when the daylight stays for a longer period is their time to bloom.

Examples of long-day plants include the most common herbs and vegetable plants like spinach, dill, hibiscus, clover, and aster.

Then there are also certain day-neutral plants whose blooms do not get affected by the length of the day and night.

Examples of such plants are vegetable plants like cucumbers, tomatoes, and corn.

Houseplants in artificial lights

When it comes to houseplants, it is recommended to get plants that can grow well during more hours of darkness.

This is because houseplants do not get the same amount of sunlight that outdoor plants get, so 12 hours or more of sunlight may be difficult to get indoors.

However, if your house gets too limited sunlight, it is best to invest in artificial lights.

Artificial lights cannot replace natural sunlight but can give plants the necessary nutrients and energy.

However, even if you get these lights, remember you do not need to keep them on all the time.

Your plants need darkness just like light, so remember to put it off at night. 

The myth regarding plants growing at night

There are misconceptions that plants grow only during photosynthesis which is not true.

In reality, plants grow all day and night during photosynthesis and respiration.

After dark, the photosynthesis process stops while respiration continues.

So plants grow day and night, but the rates sometimes vary depending on the species. 

Can plants be watered at night?

The answer to this question depends on certain environmental factors, but it is advised not to water at night in most cases.

This is because at night, due to darkness, the water that you give to plants does not get evaporated.

This means that the soil stays saturated in water for longer times.

Also, at night in the absence of light, plants do not need much water, are thirsty, and do not photosynthesize.

Less water absorption keeps the soil wet all night, which leads to plants standing in the wet soil all night, increasing the chances of root rot.

Another problem is that water splashes on the leaves while watering and makes them wt.

During the day, the water gets dry, but at night, the leaves also stay wet and wet leaves attract a lot of pests and fungus.

Do plants grow better with music?

Numerous studies did reveal that music accelerates and promotes healthier plant growth.

In 1962 an Indian botanist conducted several experiments and concluded that plants grew more than 20% extra when it was exposed to music.

A certain Colorado-based greenhouse owner confirmed that plants exposed to rock music died quickly, and those exposed to classical music thrived.

He also found that corn and soy plants exposed to music grew lusher and yielded larger results. 

How does music affect plant growth?

During a study, researchers found that music did not affect plant growth, but the vibrations created by sound wave music did.

The vibration produced by the sound stimulates the plant’s hormones, and it produces more nutrients.

So sound is transmitted through waves that travel through mediums like air or water.

These waves cause the medium to vibrate, so when you switch on music, the sound creates waves in the air that cause our air drums to vibrate.

In this way, the pressure from sound waves vibrations reaches the plants.

So clearly speaking, they cannot hear the music but can feel the vibrations.

The vibrations of the rock music created more pressure that was not conducive to the plant’s growth.

However, scientists and researchers have not yet reached conclusions about the impact of music on plants.

They say they must conduct more tests under diverse environmental conditions to reach a definite conclusion.

Final words

Darkness and light are equally important and play vital roles in the growth of plants. A plant cannot survive in full darkness nor in complete light all the time.

It was a misconception that went on for centuries that plants sleep at night and do not grow anymore without light. Studies and researchers found that the growth of plants continues all through the night, but its pattern changes, and just before dawn, the growth reaches the highest point.

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Reference: Plant Responses to the Dark Scenario, Plants Can Sense Midnight