why does my plant have brown spots?

Green, lush, shiny and beautiful leaves are the perfect indication of your plant's happiness. If you have managed to reproduce to a large extent the habitat from which the species originates or if you have at least managed to create a space where it feels very much at home.

Everything seems to be going great, but one day you discover a little brown spot on the leaf. That's OK, but what happens if those dreadful spots threaten to spread to all the leaves?

Don't waste time, because the spots, discolorations and other details that appear on leaves and stems, besides detracting from their beauty, are the signs that plants use to warn you that something is out of order.

Let's learn how to diagnose, recognise and solve these problems that cause brown spots on plants.

why do plants get brown spots?

Plants are living things that take up water and nutrients from the substrate. These travel from the roots and spread throughout the plant to the leaves. If the roots, for one reason or another, cannot meet the plant's demand for moisture, then it will begin to distribute it as far as it will go, leaving the leaves (especially the tips) without an adequate supply of water, which will cause the tissue to dry out and die. But not all brown spots are due to this cause. Sometimes they occur due to the action of pests and fungi that lodge in the leaf of the plant, reproducing and spreading through the air by contact with tools and others.

Although these brown spots often do not affect the life of the plant directly, as they do not attack the roots, they do affect the process of photosynthesis by destroying the green surface of the leaf, which is where this vital process that allows the plant to synthesise its own food begins. This results in a weak plant that in the long term may end up dying. This is why it is essential to diagnose and solve this problem.

Diagnosis of brown spots on plants

The first step in solving the problem of brown spots on plant leaves is to make a proper diagnosis of the causes. Not all brown spots are the same, so you should take your affected plant, sit with it in a well-lit place and even get a magnifying glass because you should look closely at the spots that have appeared, looking for the following characteristics:

• Location

where on the leaves are the spots? If they are concentrated on the tips, it is very likely that they are caused by a problem related to watering or humidity. This type of spots also appear when there is excessive heat, especially if the leaf is wrinkled.

• Colour

The colour of the stain is important. Check the shade if it has edges or centre of another colour such as red, black or yellow. If it is only a more or less even brown colour, it may be caused by sun or watering and/or moisture problems. Stains with coloured borders are usually caused by fungi and bacteria. For example, if the spot has a yellow border, it may be caused by a bacterial infection. If the stain has black, mould-like edges, it may be a fungus called septoria.

• Shape and distribution

is the spot rather round or oval? is it concentrated in a single section or does it spread across the leaf? It is easy to confuse (especially for beginners) a leaf that is wilting because it has completed its life cycle with a leaf affected by a problem or disease.

Also, the location of the spots will tell you a lot about what has caused it. If it is on the higher leaves, right where the sun is shining on it, it could be overheating. If you see the spots are even and on the tips, it is a lack of watering, but if they are small dots that are grouped together and spread along the leaf, it may be a fungal or bacterial infection.

• Quantity

is it a single spot that grows over time? are they small dots that are clustered together? The number of spots and the way they spread or reproduce will tell you what kind of problem is causing them, as fungi and bacteria reproduce quickly and can affect all adjacent plants in a short time. If the problem is one of care, then the spots will be more contained and slower to appear.