3 Reasons For White Spots On Petunia [Control & Prevention]

Do your Petunias have white spots that are ruining their beauty?

The beautiful petunias brighten up the landscape. But the white spots on leaves and flowers can make it look very ugly.

You might be wondering what causes these spots on petunias. Well, petunias are usually a very tolerant type of plant but they are troubled sometimes by some conditions.

Now the question: why do petunias get white spots?

 Pests, Diseases, and fertilizer burn are the main 3 reasons that cause white spots on petunia leaves petals and blossoms.

Don’t worry, this article is here to help you get all the probable answers. So, keep reading to find out what is causing your petunias this problem.

Let’s get started-

What Causes White Spots on Petunia Leaves & How to Fix

1. Pests of Petunias

Thrips feed on petunia flowers and leaves and cause tiny white spots on the petunia.

Thrips also transmit viruses to petunias. Severe infestation of them deforms the petunia leaves. Controlling thrips is not easy because they hide inside the petunia flower.

Spider mites also feed on the plant and cause white spots on petunias. They are also very tiny. You can confirm their presence by seeing small webbing on the flower and plant.

Control Measure

Thrips are very tiny. So look for them in the leaves and flowers carefully. Apply the best insecticide to your petunias (our pick: Monterey organic Garden Insect Spray)

You can also wash them off with a strong spray of water. Apply neem oil and horticultural oil to your petunias every week on a regular basis. Their homemade recipes for them are given below.

#Recipe 1:- Horticultural Oil Recipe


  • 1 tablespoon of liquid soap 
  • 1 cup of any cooking oil like olive oil or vegetable oil. 


  • Mix these ingredients very well and store the mixture in a bottle for later use.
  • Add a tablespoon of this mixture with every cup of water and pour it into the sprayer.
  • Spray very thoroughly on your petunia leaves and flowers every week. 

#Recipe 2:- Neem Oil Recipe


  • 1 tablespoon of neem oil 
  • Half a gallon of water 


  • Mix the ingredients and spray in the petunia leaves and flowers every week.

#Recipe 3:- Tomato Leaf Spray Recipe


  •  1 cup of fresh tomato leaves
  • 2 cups of water


  • Chop off the tomato leaves and let them stay overnight in a cup of water. 
  • Then strain out all the leaves and add another cup of water to dilute the solution. 
  • Spray on the petunia leaves and flowers twice a week. 

Note: In the case of all homemade recipes, always use a small portion of the mixture in a small leaf. Sometimes it can hurt the plants. So it is better to be sure before applying it to the whole plant. If the leaf burns or discolors add some more water to the spray solution and try applying again.

2. Fungal Problems Of Petunia

Gray mold is a common disease of petunia flowers and many other flowers. The white spots eventually turn grey. It can completely destroy the petunias. This disease can easily spread to other plants. in wet and humid conditions.

The entire plant can get wilted. The petunia flowers also start to drop. This disease occurs when petunias are always in moist condition.

Another fungal problem is powdery mildew. It is a fungal disease. It starts with white spots on the leaves. But as the condition worsens the spots start getting on the petunia flowers. Powdery mildew prefers humid temperatures and shady conditions. These powdery white spots look like dust.

Petunias get attacked by Tobacco Mosaic Virus. Thrips are the ones that spread this disease. The petunia leaves get curled and have mosaic-like white specks. It is a very serious disease. Because the leaves get distorted and the petunia plant soon dies.

Control Measure 

To get rid of the white spots, pick the best fungicide for petunias (Our Pick: Bonide Copper Fungicide)Always apply by following the label instructions. Remove the white-spotted petunia flowers and leaves to stop the spreading of the disease. Put them in a plastic bag and discard them safely.

But sadly Tobacco Mosaic Virus has no cure. Once it has infected the petunias it rapidly kills them.

You can apply some easy homemade remedies to control fungal problems.

# Recipe 1:-Milk Spray Recipe


  • 200 ml of sour milk 
  • 200 ml of water 


  • Mix very well
  • Use it as an instant mixture 
  • Spray it twice a week on your petunias until the fungal problem stops.

#Recipe 2:- Vinegar Spray Recipe


  • 3 teaspoons of apple cider vinegar 
  • 2 liters of water
  • Few drops of liquid dish soap


  • Mix the ingredients very well and spray on the spotted leaves and petunia flowers twice a week.

# Recipe 3:- Baking Soda Spray Recipe


  • Baking Soda 1 teaspoon
  • Few drops of liquid soap
  • 1 liter of water


  • Mix the ingredients well
  • Spray thoroughly on both sides of the petunia leaves and flowers.
  • It’s very effective against powdery mildew

Preventive Measure

Plant your petunias in a sunny place with good air circulation. Petunias prefer full sun to produce good blooms. Use disease-resistant petunia varieties.

While watering them avoid wetting the leaves. The best way to control Tobacco Mosaic Virus is by preventing it from attacking. Since thrips transmit this, kill them as soon as you notice with a good insecticide.

3. Fertilizer Damage of Petunia

Another reason for white spots on petunia leaves is fertilizer burn. Sometimes we over-fertilize the plants in order to get more flowers. But it can backfire. 

Overfertilization adds too much salt to the soil. It burns the petunia roots. As a result, the roots transfer less water and nutrients to the plants. And the petunias start getting white spots. 

Control Measure

Fertilize your petunias in the right amount. Too much nitrogen application will invite more pests. So, apply the best and most balanced fertilizer that will also help the blooming (our pick: Miracle-Gro Water Soluble Bloom Booster Flower Food). While applying, follow the label directions on the fertilizer pack. 

If you think the white spots are due to overfertilization, water the soil generously and let the water drain completely. This will help leach some extra salt.


Petunias are relatively pest and disease-free plants. But thrips transmit viral diseases that are fatal to petunias. Also, environmental conditions bring fungal problems that create white dots on petunias. Thus, their beautiful appearance is destroyed.

Your petunias can’t tell you their problems. So, you have to keep an eye on them. Whenever you see white spots inspect the cause of it. See if there are pests present or if the petunias are in shady and humid conditions.

 I have tried to include all the possible solutions. And I hope this article helped you get rid of the white spots on your petunias without any trouble.

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