Mesophyll Cells: Why Do They Collapse and What You Must Do

Mesophyll cells are ones that get damaged for many reasons, like low temperatures, water stress, lack of nutrients, diseases, and physical damage. Unfortunately, you can’t reverse the impact, but there are some effective ways to prevent it from happening.

Causes Mesophyll Cells to Collapse

If you consider fixing this issue, you surely can, so keep reading to know all about it.

What Causes Mesophyll Cells to Collapse?

The causes for mesophyll cells to collapse are low temperatures and cold water usually harms them. In addition, a lack of water and nutrients can also destroy these cells. Furthermore, mechanical damage on leaves might also be the reason behind the collapse of mesophyll.

– Low Temperatures

You may start seeing how the orchid leaves turn yellow, brown, or, even worse-black, and it’s winter. It is a no-brainer that the cold temperature has hurt mesophyll. Most people often fail to comprehend why the leaves discolor when the mesophyll cells get damaged. You can only understand the phenomenon if you know the structure and mesophyll cells location.

They are located in the middle layer of a leaf, so they are the center of the main things. It is also important for you to know that there are two types of mesophyll, spongy mesophyll, and palisade mesophyll cells. Both mesophyll cells function to keep the orchid leaves healthy; unfortunately, both of them can get damaged when the temperature goes low.

Most orchids can start to exhibit damage at 45 degrees Fahrenheit; on the other hand, a Phalaenopsis type of this plant, may tolerate up to eight hours at 35 degrees Fahrenheit without any issues, but of course, just as all of its leaves are mature. Arabidopsis thaliana can even tolerate below-freezing temperatures to some extent.

How this happens is that when it comes to the leaf anatomy the spongy mesophyll is at the bottom of the middle layer and is loosely packed. Usually, you would also wonder, why are spongy mesophyll cells loosely packed, but the reason is to perform their main role, which is gas exchange. The intercellular spaces between them allow the gas to travel freely.

Palisade cells are on the upper layer and have chloroplast, which has chlorophyll in it, the agent that gives green color to leaves. In short, when palisade cells get hurt, the green color fades away, and the collapse damage becomes visible, due to the temperature.

But the intensity of damage varies from orchid species to species. The plant’s genes and environmental factors affect how well an orchid can withstand or adapt to cold stress. While some species of orchids can tolerate brief periods of near-freezing temperatures, others can easily get injured by colder temperatures.

– Cold Water

Applying cold water is also a big reason behind plant cell death, and when roots absorb such water, they face a shock first. This slows down nutrient uptake, which reduces the photosynthetic capacity of orchids.

After this happens, this cold water travels to the leaves and forms ice crystals there. As a result, both palisade and spongy mesophyll cells stop and start to degenerate. In this case, the cell expansion also takes a hit and when this happens, the mesophyll collapse is inevitable.

Furthermore, some people also sprinkle cold water on plants. Even if they don’t, water splashes can fall on the leaves during watering, which can damage cell walls, guard cells, and mesophyll cells chloroplasts. This doesn’t mean that the orchid plants can also face leaf mesophyll damage if cold condensation.

The damage from cold water is common when it is winter. A mesophyll cell can collapse in the water below 25 degrees Fahrenheit, and in this case, the Arabidopsis thaliana may tolerate it but don’t expect to do the same, which is why in winter, cold water is a crucial issue.

The problem is- orchids do not show symptoms of mesophyll collapse until four weeks. So, if you continuously mist or water your orchid with extremely cold water, you will discover the collapse after a month, because it may take time.

– Lack of water

Although rare, dehydration can also cause mesophyll disintegration in the plant you are raising. It occurs when you don’t water for weeks. Leaf curling, discoloration, wrinkles, and wilting are signs of water stress; in short, these cells would go under stress due to the lack of water.

Water is crucial for orchids cause all the internal processes, including chloroplast movement, depend on it. The dryness will cause energy loss, and the cells will rupture.

– Nutrient Deficiencies

Orchids require a consistent supply of nutrients to maintain strong, colorful, and healthy leaves. If the one you are growing is not getting enough nutrients from soil or fertilizer, it will face many problems, including the collapse of the cells responsible

When the nutrients are unavailable, the chlorophyll synthesis will be abnormal, ultimately harming the responsible cells. Furthermore, the gas exchange between the intercellular spaces will decline, and oxidative stress within the cells can increase.

Nutrient Deficiencies

Moreover, enzyme synthesis and photosynthetic capacity get reduced a lot. All of these things can play their part in the damage to the cells, and they would not be able to stay as strong as they should, which is why they collapse.

Most inexperienced gardeners need to learn when to apply fertilizers. They keep assuming that the potting soil has all the nutrients needed to maintain the orchid’s health. When the minerals get depleted with time, an orchid will tell you something is wrong by turning its leaves yellow or gray, and so this discoloration can also be caused by mesophyll damage.

– Different Diseases

The orchid plant can also experience mesophyll deterioration due to diseases of different kinds. The most prevalent diseases that affect orchids and cause damage to leaves are root rot, leaf blight, fusarium wilt, and downy mildew.

Illnesses usually invade orchids when you add more water than they need. Sometimes it would be due to dirt and pet feces can also lead to disease attacks. Furthermore, high humidity can sometimes cause fungus to grow, as it likes moisture.

As a result, you may regularly inspect your orchid’s leaves, and if you notice any spots or leaves wilting, the disease has attacked them. In the early stages, the gas exchange slows, and the cell wall bursts. The damage spreads quickly to all the leaves, giving the orchids an unaesthetic look.

– Physical Damages

In some cases, mechanical damage can also cause these cells to collapse. Usually, the damage occurs during the repotting and relocation. You may brush the orchid to a hard thing or simply don’t handle it properly, which can lead to cell damage.

Also, storms and rain can harm the cells present in the leaves. It’s no secret that leaves are delicate. You can easily hurt them by scratching your index finger. When you let them endure the coming storm, the mesophylls cannot sustain the wind or rain pressure and can get severely damaged.

How To Protect Mesophylls From Collapsing?

To protect mesophyll cells from collapsing, you should always add lukewarm water to the soil, and if the temperature has dropped extremely low, we suggest you bring the orchids inside and place them near a heater.

Protect Mesophylls From Collapsing

In addition, giving a timely dose of fertilizers also keeps the mesophyll healthy.

– Apply Lukewarm Water Adequately

To prevent mesophyll deterioration in orchid plants, it is very important to water them correctly. The correct way is to add lukewarm or room-temperature water in controlled amounts. You can even spray it if you think you will end up overwatering, which will help it stay in control.

Also, don’t just add water out of nowhere; instead, you should also regularly check the moisture condition in the soil. Only apply water when the soil is partially dry. Generally, you must give water twice a week on hot days and once a week in winter.

– Bring Orchids Inside and Keep it Warm

To protect your orchids from low temperatures, the best thing to do is to bring them inside your home and place them near a heater or adjust the thermostat, to a warmer range. There are various types of space heaters that you can use in this situation, but the popular choices are infrared and gas heaters. Use the one you already have in your home, or buy any affordable one that will do the job.

However, you must be careful how far you put your orchids from the heating source. Putting them close can lead to more problems like leaf scorching. There is also no specific answer to how far you can place your orchids from a heater. In this case, you must aim to find the perfect spot that does not overheat the orchids and does not let them face cold stress.

– Give Fertilizers Timely

It is very important to give adequate fertilizer to the orchid plant to protect it from damage. Once a month, fertilization is enough for them to keep on growing. There’s another recommendation. Instead of giving a full nutrient dose every month, you can add a lighter fertilizer, which is almost one-fourth of the quantity weekly with the irrigation.

Also, it is better to avoid powdered or grained fertilizers as they may burn the orchid roots. In this case, you may go ahead and try those fertilizers which are specifically made for orchids, specifically. On the other hand, you can also go for liquid ones, but you must follow the instructions on the bottle, so that you won’t stress your plant.

Give Fertilizers Timely

Also, the timing of the fertilizers is crucial too. Orchids need nutrients the most when it’s time for new growth. It happens during the spring and the summer. In winter, orchids enter the dormant stage, so they don’t need fertilizer doses.

Furthermore, you should not add nutrients when it’s time for development. It is because the excess of minerals in the soil can divert the orchid’s focus from flowering to vegetative growth. If you remember these instructions, the orchid will never face nutrient deficiency or stress again.

– Prevention From Diseases

If you wish for the mesophyll cells and bundle sheath cells to stay healthy forever, what you can do is protect them from diseases. You should carefully water the orchids, as overwatering is the leading cause of fungal diseases.

It would be best to uproot weeds as they can facilitate pathogens to cause diseases. Also, cut off any discolored part you see, as it may be infected. Doing this will stop the disease from spreading in its early days.


All-inclusive mesophyll cell collapse is a big problem when you don’t take your orchids properly. Unfortunately, the damage is irreversible, and following preventive care is the only way to avoid it:

  • Low temperatures, cold water, nutrient deficiency, diseases, and mechanical damage are the reasons behind it.
  • Make sure to add lukewarm water to the orchids.
  • Bring the orchids inside and place them near a heater or adjust the thermostat in case of cold stress.
  • Apply nutrients once a month or 1/4 dose every week.
  • Keep following care measures, or else the diseases will invade.

Following these points, the mesophylls will always stay healthy and functional!

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