how does humidity affect transpiration

Wondering – how does humidity affect transpiration? This guide will explain this issue in detail!

Growing plants are continuously using their water deposits and transpiring water in a cyclical state to keep from dehydrating.

However, climate factors such as humidity can change the amount of water a plant has available.

Natural climates can be tricky to navigate when keeping plants hydrated and healthy.

Controlled climates are preferable to promote the growth and upkeep of certain plants and flora, but occasionally it isn’t possible to do.

Humidity affects the stages of plant stomata opening required for the fauna to “breathe” or transpire. When the humidity is high, transpiration rates become too low, causing the plant to close its stomata and suffocate.

Here, we will discuss what transpiration is, the effects humidity has on plants, and other factors that influence transpiration.

What Is Transpiration?

To understand how humidity affects transpiration, we must first determine the definition of transpiration.

For growing plants, water evaporates rapidly and continuously from its exposed leaves.

As this water vaporizes, the roots of the plant quickly absorb water from the soil to replenish it.

This process of water evaporation and replenishment is done through the stomates of the plant’s leaves.

Studies have suggested that this process of transpiration aids the plant by providing the energy needed to transport water and helping the greenery cool off via heat dissipation.

Note: Imagine transpiration like the human nervous system. Just like we sweat to cool down, so do plants transpire water to keep cool.

How Much Do Plants Transpire?

does plants transpire

Plants and other vegetation make up nearly 20% of our world. Knowing their functions and how they operate is integral to preserving the crops we use for oxygen and food.

Transpiration is a vital system that helps plants stay hydrated and compliments the process of photosynthesis that it needs to produce food.

The transpiration rate of plants is dependent on several key factors, one of which is how much water the plant moves from the soil to the leaf.

A singular leaf can transpire around 90% of evaporated water regardless of the size of the stomatal pores, which usually make up only 1 to 2 percent of the area of most leaves.

How Does Humidity Affect Transpiration?

Humidity can cause all kinds of adverse side effects, from frizzy hair to a feeling of overbearing fatigue.

In plants, humidity can cause just as much damage. Humidity is the amount of water vaporized into the air and is practically invisible to the human eye.

So, how does humidity affect the rate of transpiration in plants?

Humidity levels can affect the time and duration of the opening of the stomata of the plant.

Stomata are vital as they are effectively the plant’s cooling system. If conditions become too hot, a plant will close off its stomata to conserve water.

The stomata closing can be detrimental if shut down for too long since the plant has no other way to transport carbon dioxide and oxygen from the stems.

The plant will slowly begin to suppress the transpired gases, causing it to suffocate and wilt.

How Does High Humidity Affect Transpiration?

high humidity affect transpiration

Transpiration rates in plants can be stunted by high levels of humidity in the air.

Lower transpiration rates occur because in humid climates there is more moisture and water already in the air.

Since plants can only hold a certain amount of water at a time, they must stop or slow the rate of transpiration before they reach their threshold.

Plants that are root bound in high humid climates have evolved with larger leaves, citing the need for more intake of sunlight and to reduce the risk of excessive water loss.

Conversely, plants found in low humid areas contain smaller leaves to keep water evaporation low and take in less sunshine.

Note: Leaves with larger surface areas transpire faster than leaves with smaller surface areas.

What Other Factors Can Affect Transpiration?

factors transpiration

We’ve established that humidity can affect the transpiration rate in plants, but did you know that other factors can contribute to water intake?

Soil quality, wind, and several other factors can also affect transpiration rates in plants.

1. Quality of Soil & Transpiration

Any gardener will tell you that the soil quality you use in your plants is paramount to keeping flora and fauna looking bright and healthy.

If the soil becomes too soft and filled with extra moisture, plants will continue to transpire more since it absorbs more water from the roots.

2. Wind & Transpiration

The wind is another crucial proponent of the transpiration rate as it can increase or decrease the relative humidity surrounding a plant.

Cooling air drafts can cause water evaporation to happen quickly, while warmer drafts will provide the air with more moisture.

3. Plant Cuticles & Transpiration

The components that make up a plant can impact the process of transpiring water.

If the cuticle on a plant has a waxy surface, it can be a barrier that prevents water from permeating its surface.

Waxy surfaces can cause the leaf to hold in heat, reducing the rate at which water evaporates from the plant.

Trichomes, which are modest structures on the surface of leaves that look like hair follicles, can also inhibit water loss by enclosing the humidity close to the leaf’s surface.

Other Factors That Can Affect Transpiration

Ultimately, some plants merely transpire more or less than others.

The species of the plant, the density of the roots in the soil, and the overall climate are just a few factors that contribute to the rate of transpiration, as well as:

  • The shape and size of the plant’s leaves
  • How old is the plant?
  • Too much or too little supply of sunlight

Does Photosynthesis Affect Transpiration?

Photosynthesis process

Air and water both affect plants in many different ways, including changing the rate at which they transpire.

Along with those two crucial factors, plants need energy and sunlight to complete the process.

It is at this point where photosynthesis makes its appearance, as transpiration usually occurs during the process of photosynthesis.

As the plant’s stomata open during transpiration, they release carbon dioxide or CO2. The plant will take the carbon dioxide and the water and use them during photosynthesis.

Note: Transpiration is a key element in aiding the process of photosynthesis as it supplies the water required in producing the carbon dioxide that photosynthesis needs.

Does Climate Control Help Transpiration?

Using a system to control the climate and weather surrounding flora is immensely beneficial.

Not only can climate control aid plant growth, but it can also fight off pests and bacteria that hinder transpiration.

Highly humid conditions promote mold and bacteria growth that induce crops and other plants with diseases.

climate control

Other side effects include crown fungus, root rot, and facilitating the environment for pests like fungus gnats.

These bugs and bacteria thrive in moist soil and can prevent the plant from operating its systems normally, including prohibiting the process of transpiration.

Keeping the area climate-controlled inhibits mold growth and other plant pests by stabilizing the humidity.

Read Next: What is a Comfortable Humidity Level Outside?


We’ve covered everything from climate control to photosynthesis, But perhaps now you have the answer to, “How does humidity affect transpiration?”

Water loss in plants, while a common problem, should be monitored closely to ensure the survival of the plant.

Note: The higher the level of humidity in the air, the slower the rate of transpiration will be in the plant.

When the weather is warm, plants may close off their stomata to ensure water is conserved. Many plants have evolved to have larger or smaller leaves so that transpiration can still occur.

Plants need to endure the transpiration process to enhance nutrient uptake, cool the plant to keep it from dehydrating, and allow for a smooth transition to the process of photosynthesis wherein the plant will make its food.