Can You Water Plants In The Sun? The Truth Revealed


Water is an abundant yet valuable substance and an instrumental resource for gardening and general farming, regardless of the scale. Watering is essential for healthy plant growth and, if done correctly, may mean the difference between a lush, attractive landscape and dry, withered stumps. However, even though experts and gardeners rarely butt heads on water issues, there are a few questions about watering plants in the sun.

You can and should water your plants in the sun. Contrary to common beliefs, water droplets on the plants will not amplify the sunlight or trap excessive heat and cause damage to the plants. However, you may need to use more water as the sun will cause the water to evaporate quickly.

I know there are a lot of gardening myths out there, and they can influence an amateur gardener to make wrong decisions that may affect the health of their plants. Therefore, it is necessary to set the facts straight. The rest of this article covers the whole truth about watering plants in the sun and provides some helpful tips for watering your garden.

Why Do People Believe It Is Harmful To Water Plants In The Sun?

People believe myths for many reasons, sometimes on legitimate grounds. Moreover, popular myths are usually rooted in fact, having some shred of truth, and may even have been accurate at some point in history. In the case of watering plants in the sun, the common, albeit erroneous, belief stems from a desire to save plants from drying out.

Some people believe it is harmful to water plants in the sun because the water droplets could concentrate sunrays and burn plant leaves by forming microscopic lenses. They also think the sun may heat the water on the surface of the plants and scorch them, damaging the foliage in the process.

These beliefs are not valid, and the sun does not form microscopic lenses or heat traps when it hits the water on the plant surface. If this were the case, most plants on the planet would suffer severe damage every time the sun shines on them after it rains.

The origin of this myth is unknown, but ideas of sunlit water lenses have been circulated for a long time and even till today. 

However, the consensus is that most people believe that water droplets can focus light rays intensely enough to act as tiny microscopes and microwaves.

Surprisingly, until 2009, no one in the gardening or scientific community had previously checked to see if the scorching phenomenon happens, as many believed. Fortunately, a couple of Hungarian scientists released a study on this subject titled “Optics Of Sunlit Water Drops On Leaves: Conditions Under Which Sunburn Is Possible.”

The paper was published in the New Phytologist, a high-quality, peer-reviewed journal devoted to plant science research. 

In this study, the analysts placed water droplets on the leaves of Norway maple and Ginkgo plants and waited for them to evaporate in the sun. The evaporation took about an hour on average, and they found no sign of harm after a thorough examination of the plants.

Therefore, they proved that it is implausible that watering your plants in the sun can cause them to become sunburned or scorched in any way.

Therefore, why do many people still believe this myth in the face of peer-reviewed evidence? According to one theory, although the Hungarian researchers used ordinary tap water, various other substances can make their way onto leaves. Some examples are acid rain, saltwater, chlorinated water, sewage, fertilizer, and other chemicals.

These substances can leave peculiar marks on leaves that may resemble burn damage. Some can even dry sections of the leaves via osmosis, leaving scorch marks.

There are a few reasons you might want to avoid watering your plants in the sun, but the risk of burned foliage is not one of them.

What Happens When You Water Plants In The Sun?

People opposed to watering their gardens in the hot sun may avoid watering parched, wilted plants in sweltering weather for fear of burning them due to the “lensing effect.” 

However, this act may cause considerable damage to the plants as they will be starved of the valuable resource at a much needed time. What then happens when you water plants in the sun?

When you water plants in the sun, the water droplets quickly evaporate. Although this evaporation rate is due to the high surrounding temperature, it has no direct effect on the plants. However, the high level of evaporation may cause very little water to get to the roots of the plants.

Some gardeners believe it is inefficient to water plants in the sun since it may just be a waste of resources as most of it will evaporate before entering the soil. However, I believe the advantages of providing water to severely parched plants when they are most in need will outweigh any possible danger or depletion of resources.

Plants use their roots and leaves to absorb water used for biological processes. The processes by which plants absorb water through their roots and leaves are called transpiration and capillary action.

Plants absorb water by capillary action through the xylem. The xylem is a structure made up of tiny tubes right beneath the surface of the stems. Water is drawn upwards from the soil by the molecules in this structure, allowing the plant to stay hydrated.

Evaporation is necessary for water absorption and extracts the molecules from the top layer of the xylem structure, resulting in transpiration. As a result of the removal, a vacuum is created, which causes the capillary action to happen.

Hence, watering plants in the sun’s full glare, where the evaporation rate is high and the moisture in the soil is low, is beneficial to plants. However, you may need to use a lot of water to be effective.

When Should You Water Plants?

Now that we have established the truth about watering plants in the sun, it is only fitting that I discuss the optimal time of the day to water the plants in your garden. 

Watering plants in the sun will not damage them, but it will cause you to burn through a lot of water to ensure they get enough moisture to absorb water through their roots. Therefore, what time of the day should you water plants in your garden?

You should water your plant in the morning or evening before the sun rises or when it has set. Temperatures around this time will reduce the evaporation rate and ensure that the plant receives enough water through capillary action. You should also water the plant often, so the soil does not dry out.

However, watering your plants in the morning is better than in the evening since the plant will dry long before the sunset. 

Since nighttime is usually cooler, water tends to sit in the earth, around the roots, and on the leaves. This dampness can promote rot, fungal development, and insect infestation.

You should also take care not to overwater as this may affect the support of the plants and cause them to fall over or grow awkwardly. Overwatering can also cause some plants to lose their drought resistance and wilt if the soil water moisture content drops.

The best way to tell if a plant is well-watered is to check for wilting. However, note that some herbs will appear to wither in direct sunlight to conserve moisture and rehydrate when the temperature drops in the evening. This process is known as temporary wilting.

The age of the plants will also determine what time and how often you need to water them. Young seedlings need as much water as possible, as long as they are not overwatered. However, mature plants need less water as they have more extensive root systems and sturdier shoots.

Tips For Watering

Here are a few tips for watering plants:

  • Water the plants in the morning to ensure that the soil stays moist throughout the day.
  • Do not water the plants too often or too infrequently. Provide enough moisture for the plant species you wish to cultivate and keep the soil consistently moist.
  • Ensure you water the soil, not the plant itself. 
  • It would be best to water outdoor potted plants at least once a day, although your plant species may have different needs. 
  • It would be best to use wands like the GREEN MOUNT Watering Wand (available on Amazon.com) to water plants efficiently. Wands like this one soak the soil gently and evenly around your plants’ roots, ensuring that you don’t get too much water on your plants’ leaves. 

Conclusion

Water droplets on plants do cause harm to the plants. Therefore, you can water your plants in the sun. However, the sun can cause the surrounding temperature to rise and increase evaporation, but it has no direct effect on the plants in the garden.

The high level of evaporation may cause little water to get to the roots, and you may need to water them more often to ensure the plant does not dry out. Furthermore, you should water your plant in the morning or evening to ensure that the plant receives enough water through capillary action.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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