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Help! What’s Eating My Petunias Alive? Identify the Culprits Ruining Your Flowers

Help! What’s Eating My Petunias Alive? Identify the Culprits Ruining Your Flowers

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Whether you are a seasoned gardener or have just begun displaying a beautiful assortment of flowers in your yard, you know your plants are exposed to animals, bugs, and diseases that can alter their appearance. There is only so much you can do to keep animals away from your plants but there are things you can do to protect your pretty plants, such as your petunias.

While these annuals appear to be delicate, they are actually fairly low maintenance and make a nice addition to your flower bed. Their colorful flowers attract not only a sweet dash of hues in an assortment of pastels, but they also attract their fair share of bugs, insects, and diseases.

What Exactly Is Eating Your Petunias?

In order to keep your petunias in good shape you need to first identify what is causing the decline in their appearance. Many pesky bugs can eat at your flowers and make them appear as if a small animal is munching on them.

There are ways to decipher who the true culprit is.

Bugs and Insects


Caterpillar On Leaf

Two of the most common caterpillars that go after petunias are the tobacco budworm and the variegated cutworm. Both of these pests cause substantial damage. The tobacco budworm feasts on the petals and buds of the flowers that are unopened.

The variegated cutworms help themselves to the flowers and roots of the petunia plant finally making their home on the main roots of the plant.

Treatment: The best way to take care of tobacco budworms is to remove them from your plant by hand. Cutworms have to be dealt with when you till the soil every spring.

Cyclamen or Spider Mites

You may be able to see spider mites but cyclamen mites are usually undetected with the naked eye. Just because these pests are tiny doesn’t mean they can’t do a great deal of damage. If you see small colored spots on the leaves of your petunias, chances are your plant has mites.

Treatment: Spray the leaves from underneath with the strongest spray of water on your hose. This will get them off your plant immediately and should keep them from returning.


Another hard-to-see insect is a thrip. You will know if your plant is infested with thrips if the leaves have taken on a silverish color and there are black-dotted flecks on them as well.

Treatment: Thrips are harder to get rid of and you will have to use an insecticide spray to remove them from your flowers.


Slugs leave a path of destruction on your petunias that includes leaves that are hanging or have already fallen off and petals and leaves riddled with holes. They also leave behind a silvery-colored mucus that shows they were there.

Treatment: These little critters have to be hand-removed but if you want to make sure they don’t come back again you may want to clean up your flower beds so they don’t have any place to hide out.

Leaf Miners

Leaf Miner

As the larval form of a fly, leaf miners ruin the leaves of petunias by burrowing themselves until they leave a trail that is made up of a dead whir tissue.

Treatment: Pruning the leaves of your petunias will quickly take care of leaf miners.


Aphids are not too harmful if there are just a few but they can quickly take over your flowers by sucking the juice from the leaves until they are left curled up and deformed. When they leave their sticky mark behind they invite ants and you will be left with sooty mildew.

Treatment: A steady stream of a powerful flow of water can remove aphids from your petunias before they do too much damage.


Stunted growth

If your petunias are suffering from stunted growth it may because the soil is low in the micronutrient boron. An easy way to correct this problem is to add 1/2 teaspoon of boric acid to a gallon of water and spray it over the soil.

Phytophthora Crown Rot

If your plant doesn’t have a chance to grow or the leaves begin to die quickly your plant may have a fungus known as crown rot. Remove any plants that are infected and start over with a good quality potting soil.

You may want to use a fungicide on new plants so they don’t end up the same way.

Botrytis Blight

Watering Petunias

Overwatering your petunias could be giving it botrytis blight. If the leaves on your plant have spores on them that are brown or gray in color, simply cut away the damaged areas and reduce the amount of water you give your petunias.


Plant viruses cannot be treated in plants so if the leaves on your petunias are yellow in color and out of shape you should remove them immediately and start all over again.

Fungal Infections

Most fungal infections are spread when your petunias are watered too much or not enough. Just like Goldilocks, it needs to be just the right amount of hydration. Being planted too close together hampering ample circulation is another cause for infections.

If you feel these conditions are destroying your petunias, space out your plants and get a good plant fungicide. After the first application, you can treat your flowers a few more times as they flower and bloom.

Powdery Mildew

Overcrowding your plants is the major reason they may end up with powdery mildew. You will know if your plant has it if the leaves are covered in a white powder and the entire plant looks powdery. Pick up some neem oil in the garden department and apply some to your plant.

Even though your hearty petunia plants may have their issues, these conditions can usually be treated quickly and easily.

First, determine the cause, then apply the treatment. Before you know it your flower bed will be bursting with vibrant colorful petunias and you can return to your regular maintenance routine of watering and occasionally applying fungicide to prevent further problems.

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