Humidity And Your Plants

Welcome to summertime 2020. In many areas of the country this time of year can include sizzling hot temperatures and high humidity. Neither of which are good for your plants.

Be sure to wear a hat when you garden in extreme heat and humidity.
(Courtesy: Angie Bell at

You may not realize it, but how high or low the humidity can have a major affect on plants. Plants inhale carbon dioxide through their leaves. That’s something that most if not all gardeners know. You are also probably aware that the carbon dioxide is used in the photosynthesis process of plants. When plants open their leaf pores to take in carbon dioxide, some of the moisture in the leaf is released. So the plant actually sweats water vapor into the air in order to breathe.

Dry air cause plants to release moisture much more rapidly than humid air. With humid air, water released from the leaves evaporates very quickly when it enters the air. This causes a plant to lose moisture quickly. Plants encounter difficulties when their leaves lose water faster than the roots are able to absorb it.

It’s ironic in a sense. A plant that is defending itself is causing its difficulty. In order not to lose more water to the air, a plant will nearly completely close the pores of its leaves. Although this slows down the flow of moisture from the plant, it reduces the intake of carbon dioxide. Without carbon dioxide the cells of the plant begin to die. As a result, the plant looks tired and ill.

In these conditions, it doesn’t matter how much you water the effort won’t help. Dry water pulls water out of the leaves faster than the roots can provide it to the leaves. Over watering only reduces the amount of air in the soil and results in root rot.

For plants to thrive, they need to have the right humidity. This allows them to open the pores on their leaves completely so that they can breathe without the possibility of extreme water loss. When the air is moist, the plants experience little water loses.

Misting the air will keep the environment moist. However, when plants also suffer quick temperature raises, their leaves become warm and physiologically active, as the root system is still cold and thus physiologically dormant. In this circumstance, the leaves demand a lot of water and nutrients, but the root system is unable to provide it.

In these conditions, photosynthesis, transpiration and other vital plant activity are significantly restricted causing the damage of developing flower and new growth.

Protecting Plants From Heat Stress

There are a number of things to protect your plant from heat stress. Of course, watering is essential. But you need to do it properly. It is advised that you water your plants in the early morning or evening. Use a deep irrigation system or a soaker hose to deep water your plants two or three times a week. If you don’t have an irrigation system, then use a sprinkler or hand water so that the plants get overhead moisture.

Be sure not to overwater. This can damage plants as much as under watering them. Fight the temptation and instead feel the soil to determine how moist it is. Overwatering can result in root rot or fungal diseases. Moreover, if plants are continuously overwatered, it can deprive the roots of oxygen and cause fungi to grow in the soil.

Mulching can also protect plants from high temperature and humidity conditions. A thick layer of mulch insulates the roots of the plants from both heat and cold. And, it also assists to keep the soil moist. If your region of residence suffers extreme temperatures, it is recommended that you lay at least 4 to 6-inches of mulch.

It is also advised that you offer shade to your plants during times of extreme heat. When temperatures achieve 90°F or higher, some plants including peppers, tomatoes, and eggplants won’t flower. Provide shade with a patio umbrella or lightweight fabric like a flat bed sheet. Stretch the sheet over a trellis to offer shade.

If you wish to avoid the issue altogether, select heat-tolerant plants. There are a great number of plant species that thrive in intense heat.

Finally, don’t neglect yourself when gardening in extreme temperatures and humidity. It is suggested that you garden during the coolest times of the day rather than the hottest. So, it’s best to garden in the early morning or evening. It is also advised that you work in short periods and take breaks. Also, garden at a slower pace.

Before you go out to garden, apply sunscreen to exposed skin as well as lip balm to your lips. Wear a hat. Finally, stay hydrated.

(Sources: and

About Robert Janis

Written by Robert Janis for LawnEq - Your specialists for Lawn Mower Parts and Small Engine Parts. We offer genuine premium OEM parts for Land Pride, Toro and many more dependable manufacturers.