White Spots on Leaves? Here’s What Your Plant Is Trying to Tell You
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Seeing white spots on plants can be alarming, especially if you’re seeing them on your cherished houseplant. You’re probably wondering where they come from and if your plant is going to be OK. Spoiler alert — white spots are generally fixable, but it’s important to identify the cause behind their appearance. Discover what these white imperfections are and how to prevent them.
Why Do My Plants Have White Spots?
The most common cause is powdery mildew — a fungal disease often seen in indoor plants, such as African violet, ivy, jade and begonia. Many factors contribute to this type of fungal growth, such as lack of light, circulation and warmth. Plants can also have white spots on leaves that are not caused by mildew. Other causes include mineral deposits from hard water, sunburn or downy mildew.
Although white spots on plant leaves look bad, they are generally fixable and treatable.
Identifying the Cause of White Spots on Leaves
If you’ve spotted small, white spots on the top and underside of the leaves, it’s important to identify what causes this. Here are the common causes of white spots on leaves.
1. Powdery Mildew
Powdery mildew produces white, powdery patches. As mentioned, its growth is triggered by high humidity and poor air circulation. Powdery mildew fungi can obtain nutrients from their living host plant. While it rarely kills plants, this fungal growth can cause significant defoliation, leaf distortion, or reduced growth. Affected young leaves may also turn yellow, and young shoots that are severely affected may wither and eventually die.
How to Treat
The best way to eliminate powdery mildew is to prune infected foliage. Do not compost it. Then, apply a baking soda mixture. Add 1 tablespoon of baking soda and 1 teaspoon of nondetergent soap to 1 gallon of water. You can also use one part of mouthwash and mix it with three parts of water. Spray on top, bottom and sides of the leaves.
2. Pest Infestation
Sometimes, pesky pests like mealybugs, spider mites, whiteflies and false oleander scales may cause white spots. Spider mites feed on the leaves, leaving light, fine spots. Mealybugs create a sticky, cotton-like residue. False oleander infestation manifests as white spots on the foliage, which can lead to sooty mold on the leaves. The affected leaves will soon develop yellow spots, resulting in delayed growth.
How to Treat
When introducing a new plant to your garden, inspect it for pests before integrating it into your existing collection. For light infestations, wipe the leaves with a damp cloth or a solution mixed with dish soap. You can also use insecticidal soaps for persistent pests.
3. Nutrient Deficiencies
Plants need 16 essential nutrients to thrive. When needs aren’t being met, your plant may exhibit bleached spots. For instance, a lack of iron or magnesium in newly emerged leaves may be indicated by white spots and reduced size. Magnesium is essential for producing sugars, carbohydrates and fats, whereas iron is needed for proper synthesis of chloroplast proteins and specific enzymes.
How to Treat
Check your soil. High pH can cause iron deficiency. Adjust the pH level by adding sulfur or trace-element fertilizers. Explore using magnesium-rich products, such as chelated iron sprays or Epsom salts. You can also introduce ladybugs or predatory mites to ward off pests.
4. Sunburn
Also known as sunscald, excessive sunlight can cause leaves to develop spots. Spots are either bleached white, pale or silvery-gray, often leading to brittle or dead tissue. Plants most susceptible to sunburned leaves include those acclimated to lower light and are suddenly exposed to intense sunlight. Other signs your plant is under heat stress include wilting, leaf rolling, dry leaf edges, blossom or fruit drop and dry brown spots.
How to Treat
Relocate the plant to a spot with indirect or filtered sunlight. More often than not, sunburnt spots are permanent, but they won’t affect their growth and development. Removed damaged leaves for aesthetic purposes, but this isn’t always necessary for your plant’s survival. Keep the soil moist to ensure your pant stays in good condition.
5. Mineral Deposits From Hard Water
Chalky white spots can be left behind from dissolved minerals after tap water evaporates on the leaves. While generally harmless, the spots can be unsightly. Plus, a thick buildup may block sunlight and hinder photosynthesis.
How to Treat
Wipe leaves with a damp cloth or a diluted mixture of 1 tablespoon of vinegar or lemon juice in 1 quart of water. If the spots return after washing them, it may be powdery mildew. Pay attention to the fuzzy feeling and odor.
How to Prevent White Spots on Plants
Prevention is the best way to avoid white spots. When you properly care for your plants, they become naturally more resilient to diseases and pests. Here are some preventive measures you can take.
Choose the Right Plants
Select plants that are suited to their specific environment. It’s the key to creating a low-maintenance and successful garden. Plants that are well-matched to their environment require less watering, weeding and pest management.
Some great indoor plants include snake plant, money plant and aloe vera, which only requires water every two weeks and can be beneficial for minor injuries. Before buying plants, always determine their light exposure, soil type and water requirements.
Ensure Proper Airflow
Good air circulation helps prevent fungal growth, such as powdery mildew. Avoid overcrowding the plants — give them enough space to breathe. When the weather is nice, take time to open doors and windows for better airflow. Use oscillating fans to keep air moving in the grow area, but avoid pointing them directly at the plants to avoid dryness.
Water Your Plants Correctly
Proper watering involves preventing hard-water mineral buildup and avoiding conditions that can trigger fungal growth. Avoid overhead watering. The best way is to apply water directly to the soil to keep foliage dry.
If you want to water your outdoor plants from above, do it in the morning. The sun and air can help dry the leaves quickly, reducing the risk of fungal growth.
Fight White Spots on Your Plants
By now, you already know that white spots on leaves are usually a sign of treatable issues, most commonly powdery mildew, pests or a nutrient deficiency. Proactive care is the best way to prevent this. Remember to create an environment where your greenery can thrive well.
About The Author
Olivia Elsher is a Senior Writer and Editorial Manager at Renovated. She has over 5+ years of experience writing about property related topics such as: real estate, home improvement, renovation, and construction.
