Why do brown spots appear on the leaves of plants?

Brown spots appear on the leaves

Has it ever happened to you that, no matter how much care you have given a plant, sometimes it has leaves with brown spots? They start out yellow, but then end up yellow until they fall off the branch or stem, or you remove them yourself, perhaps effortlessly.

The truth is that plants, as living beings, have their own needs. Even in specimens that come from the same parents, there will always be one more delicate than another. Because, it is important to know why brown spots appear on the leaves of plants.


Ferns have a hard time if the sun shines on themFerns have a hard time if the sun hits them

Image – Wikimedia/Arthur Gamsa

It is the most common cause. When we expose a plant to the sun without having had time to acclimatize, the next day we will see that it has spots on the leaves. They also appear if they are placed near a window through which light enters directly, as the magnifying glass effect is produced.

The spots appear quickly, from one day to the next, so it is easy to identify the cause, since the other problems that we will talk about take a little longer to manifest. Fortunately, is the one that has a simpler solution: change the site plant. Now, if we have one that has to be in the Sun so that it can grow well, such as a sunflower, carnations, cactus or others, we will have to get them used little by little:

  • During the first week, we will put it for half an hour or an hour in direct sunlight each day, early in the morning or at sunset.
  • From the second, we will increase that exposure time by 30-60 minutes every seven days.

It is possible that these spots increase somewhat in size: it is normal. That area is badly affected, and it probably won’t take long for it to turn brown. But if you have patience, the plant will get stronger.

Frosty or snowy

Young plants that are not acclimatized, or that are sensitive to cold, can have a hard time when exposed to frostand even more to snowfall. Sometimes red or yellow spots or dots appear; sometimes the entire leaf changes color, turning green or dark red; but on many occasions it dawns with brown spots.

To prevent them from getting worse, they must be protectedeither by covering them with anti-frost fabric (you can buy it here!), or putting them indoors if they are very delicate, that is, if they are plants that are at the limit of their resistance (for example, we would have to bring a kentia palm indoors if there is snowfall in our area, since it only resists frost down to -4ºC). Also, you may need to prune them. In this video we talk about it:

Magnifying glass effect (water)

Water acts like a magnifying glass when the sun hits it

Water acts like a magnifying glass when the sun hits it.

We no longer talk about the sun burning the leaves, but about the water doing it. Is, when it rests on a surface, such as the blade of a leaf, it acts as a simple magnifying glass when the sun’s rays hit it. This increases their intensity a bit.

Therefore, never, and I repeat, never, a plant should be watered from above if it is in the sun at that time. I would even go so far as to say that it is not good to do it at any other time either, not if it is done out of habit, since it would not be uncommon for the leaves to end up turning brown before their time, due to excess humidity.

Excess of water

When we water a plant a lot, or when the soil remains wet for a long time, we favor the appearance of brown spots on the leaves, which they always start at the margins of the same, and then they spread throughout the rest of the limbo. If we do nothing, there are certain fungi, such as botrytis or powdery mildew, that will cover them with white or gray mold.

To do? There are several things we have to do as soon as possible:

  • apply fungicide by leaves, flowers, trunk and roots. Always look to anticipate infections, because when the fungi become visible, it is difficult to recover a plant. you can buy it here!.
  • Reduce risks. It is important to let the soil dry out a bit before watering again. If in doubt, we recommend using a soil moisture meter.
  • If it is in a pot without holes, we will plant it in one that does.. No plant, except if it is aquatic, can live in these containers, since the roots rot due to excess water.
  • If you have a plate under the pot, you have to drain it after watering.
  • Use suitable substrates for each type of plant. For example, if it’s a cactus, use cactus soil; if it is a Phalaenopsis, pine bark; if it is a Japanese maple, since it is an acid plant, an acid substrate, such as coconut fiber, will be used. Learn More.

As you can see, there are several reasons why brown spots appear on the leaves of plants. It is important to know them and know how to identify them, in order to take the necessary measures.

Why do brown spots appear on the leaves of plants?

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