Why Are There Spots on My Plant's Leaves
Despite our best efforts, sometimes our houseplants are imperfect. Leaves get brown spots, crispy edges, holes, and so on. It is easy for us plant parents to assume the worst--disease. However, in reality, there are many more likely causes behind the spots on your plant’s leaves. Read on for the most common reason there may be spots on plant leaves and what you can do about it!
Top Causes for Spots on Plant Leaves
Dehydration or Low Humidity
When plants do not receive enough water, their leaves lose something called turgor pressure. When plants lose turgor pressure, the cells that make up the leaves collapse and die. In underwatered plants, it is often the parts of the plants farthest away from the roots that lose their water first. That is why plants will show you they are underwatered when the edges of their leaves turn brown and crispy.
Mechanical Damage
Plant leaves can be damaged and bruised just like the skin of an animal. Whether you purchased a plant online that ships to your door or you picked it up at a local nursery, your plant has been moved around a lot to get to where it is living. Even in your home, plants can be bumped by a moving chair, nibbled on by a pet, or jostled when a stiff breeze blows through the window. Because of this, mechanical damage can show up on leaves as small holes, tears, bends, or breaks. Sometimes the damage is immediately apparent and sometimes it can take days to show up.
Incorrect Light Levels
Following light guidelines for any plant can really make the difference between life and death. Lighting that works for one plant may be too much for a plant even within the same plant family. Just like human skin, plants can burn in direct sunlight if they are not made to handle it. Light damage can show up on a leaf as a greying or browning at first and can lead to the entire leaf crisping up and dying. On the flip side, plants that are not in enough light will not grow, lose their color, and their leaves will show signs of stress like brown or black spots.
Natural Variegation
Variegation is the natural appearance of different colors, usually yellows and whites, within a leaf. Some plants are chosen specifically for their exciting and vibrant variegation patterns. Even plants that aren’t usually variegated can produce the spots due to genetic mutations or growing conditions. Variegated plants usually need bright light in order to continue to produce variegation.
Incorrect Temperature
Cold temperatures can cause the water in your plant’s leaves to freeze. Those damaged cells will not be able to recover even when removed from the cold and will usually have a wet or slimy appearance. On the other end of the spectrum, a similar process can lead to leaf damage when plants are too hot. A leaf’s cells can burst in high heat or humidity, causing what is called edema. Edema can be as mild as small “pits” or scars in your leaves that may eventually turn brown. In severe heat damage cases, water loss will cause large brown spots to form or entire leaves to crisp up and die.
Fertilizer Salt Burn or Nutrient Deficiency
Many houseplant owners make the mistake of adding too much fertilizer to their houseplants. Too much fertilizer is often way more detrimental to a plant than too little. Fertilizers contain salts, which when added in too high concentrations can lead to the edges of your plant burning and turning brown. Nutrient deficiencies are a lot more difficult to diagnose in plants because of all of the different ways plant nutrients interact with each other. If you are fertilizing your plants during their growing months, make sure you are using the right fertilizer for your plant with all the appropriate macro-and micronutrients. For more information on how to fertilize your houseplants, check out this past blog post.
Pests
Indoor plant pests can cause any number of leave spots, holes, and color changes. Check out our post about common houseplant pests and how to treat them for some tips on figuring out if your plant is experiencing pest issues.
As you can see the list of possible leaf spot culprits is long. To the untrained eye, many of these issues can appear the same. Because the solution to solving nutrient deficiencies, for example, is wildly different from solving temperature issues, it is important to identify the true source of damage before treating a plant.
Every single problem listed is more likely than disease simply because disease always has to spread from a source. In most cases, our houseplants just don’t have an infection source. If none of these sources of leaf spots seem to be the cause, a local plant pathology lab may be able to diagnose plant diseases and recommend treatment options.
Treating Spots on Plant Leaves
The next question after identifying the cause of leaf spots is naturally, should I remove the leaf? The answer will require some judgment and understanding of how your plant grows. While spots on your plant’s leaves may be unsightly, your plant is usually still able to use that leaf to make food for itself. If you have a fast-growing or very full plant, the loss of one to two leaves may be minimal. On a plant like an orchid, which has only a few leaves to work with at a time, it will be worth keeping the leaf around as long as it is green and working for the plant. The most important thing to do after identifying the cause for leaf spotting is to make adjustments to your plant’s care or environment to remedy the issue and prevent future leaf spots. Be patient while your plant recovers and monitor it closely to make sure the damaged leaf does not become moldy or diseased.
If you’re having trouble identifying why there are spots on your plant’s leaves, feel free to reach out to our plant care team at plantcare@wildinteriors.com with a photo and a description of your plant’s current care routine and environment and we would be happy to help!