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Why Are My Petunia Leaves Turning Yellow? (3 reasons & expert solutions!)

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Petunias (Petunia atkinsiana) are beloved, no-fuss, old-fashioned flowering plants which award us by displaying beautiful flowers.

They comprise twenty varied species; all contain pretty little flowers that are versatile in color.

Petunias are usually grown as annuals, but in some areas, they are perennials and bloom from spring until winter.

Sometimes these habitually growing and long-lasting plants start turning their leaves yellow, leaving the gardener worried about: “Why are my Petunia leaves turning yellow?”

If you also have Petunia plants with yellowing leaves and you really feel worried about them, this post is especially for you.

It is because today, in this post, I will not only answer your question in detail but also will give you simple solutions to the problem.

So, without wasting a minute, let us move directly into it.

Petunia leaves yellowing—why are my Petunia leaves turning yellow
Why are my Petunia leaves turning yellow? – Image via Reddit.

Why Are My Petunia Leaves Turning Yellow?

Petunias are wonderful flowering plants, and it doesn’t seem reasonable if their leaves turn yellow; therefore, taking proper care to keep your plant safe is essential.

They need warm temperatures and well-drained soil for a healthy life.

Usually, yellowing in leaves is typical, but sometimes it occurs due to some diseases.

What you need to do is to focus on the pattern of fading of your plant. Some patterns indicate the harmful viruses which also affect other plants near them.

Therefore, the exact information of symptoms and causes tells you whether you can save your plant or not.

Here are some common reasons that can cause your petunia plant to turn yellow.

These include:

Nutrient Deficiency

Young Petunias need plenty of nutrients to stay healthy.

If your Petunia plants develop yellow leaves, your plant may need more essential nutrients to survive.

Usually, Petunias are affected by nitrogen and phosphorus deficiencies because it is seen that when Petunias are grown in nitrogen-poor soil, their older leaves turn partially or fully yellow.

Yellowing in the veins or brown spots on the leaves indicates potassium deficiency.

Micronutrients like iron are the most common deficiency in many cases.

All these nutrients are vital, and deficiency of these can turn the leaves yellow with the weakening of the stem.

If you think your plant has suffered from nutrient deficiency, you can confirm this with a simple soil test.

That test helps you to understand which soil mix is deficient in which nutrient. Thus, whichever nutrient is low, you can amend the soil with appropriate fertilizer to correct the problem.


Several diseases can occur due to minor negligence but can destroy your plant completely. These diseases include simple fungal and viral infections that harm the affected plant and others nearby.

Viral Diseases

The most probable viral disease in the Petunia plant is the Tobacco mosaic virus (TMV).

  • Plant affected with TMV shows golden yellow leaves with a mottling, streaked, or spotted appearance.
  • That virus transmits into the plants through aphids, soil, and tobacco users’ hands.
  • If your Petunias have TMV, there is no cure, and they must be thrown out.
  • The best way is to dispose of the infected plant and start with a new fresh plant in virus-free soil.
  • Control of aphids is compulsory because pests transmit most viruses.

NOTE: Never add the affected plant to the compost pile because the temperature of the compost pile is not high enough to destroy the virus, and, in that way, you can spread the virus into your whole garden.

Yellow Petunia plant—why are my Petunia leaves turning yellow
Why are my Petunia leaves turning yellow? Your plant may be suffering from fungal or viral infections—Image via Reddit.

Fungal Disease

Petunia’s leaves also turn yellow due to different fungal diseases.

  • Some common fungal infections include crown, root rot, and verticillium cause yellowing of leaves.
  • Fungal diseases are challenging to control and affected plants must be removed and destroyed.
  • Humid conditions are usually responsible for fungal diseases.

To prevent fungal infection due to humidity:

  • Water your plant deeply and let the top of the soil dry before watering again.
  • Also, provide a penalty of air to prevent the humid condition.
  • Do not leave your plant without ensuring that your plant is planted in well-drained soil.

Pro Tip: Most of the time, a plant rooted in well-draining soil and in a pot with a good number of drainage holes at the bottom will stay safe from all kinds of harmful diseases.

Over Watering

Although Petunia needs plenty of water, they don’t stay well if their petals and leaves always remain wet.

Too much watering tends petunia leaves to turn yellow and, at last, to wilt.

Therefore, if your petunia leaves turn yellow, it may be a sign that you are overwatering your plant.

  • Petunias have medium watering needs, meaning they only need water about once a week.
  • But that doesn’t mean you don’t need to water your plant for a whole week or so.
  • Take proper care and frequently check if your plant needs water or not.

(You can use your fingers to check if the soil is dry or not, or use a moisture measuring probe or a moisture meter.)

To correct the problem:

  • Water the plant thoroughly and let the top few inches of soil dry out before watering again.
  • Make sure the soil is well-drained and mixed properly.
  • Ideally, it should be half peat moss and half soil.

The purpose of peat moss is to provide the right amount of acidity to the plants.

Solution for Yellowing of Petunia Leaves

You need to begin with why your plant’s leaves are turning yellow. Most of the time, the plant’s leaves don’t get yellow until it is affected by TMV.

But you need to find the exact reason to treat your plant correctly. Now let’s move toward how you can treat your plant in different conditions.

  • If your petunia plants are affected by aphids, you can dislodge the pest by spraying them with a strong stream of water. But for severe infestation, you must spray with insecticidal soap or neem oil.
  • To correct overwatering problems, maintain a watering schedule depending upon the season and always wait for the top 2–3 inches of the soil to dry before watering again.
  • Another effective way to prevent your petunia plant from yellowing is to utilize citrus oils on the plant leaves. Like insecticides, natural oils are natural pesticides but less toxic than pesticides. Citrus oil can be sprayed directly on plants to keep insects away

For visual guide on growing and caring for Petunias, you can watch this amazing YouTube video:

Why are my Petunia leaves turning yellow? This video will help you to grow and care for your Petunia plants in a proper way—YouTube.

That’s all for today’s discussion! Now it’s time to move toward the conclusion.


Why are my Petunia leaves turning yellow, you said? Hope you have your answer!

In most cases, petunia leaves turn yellow because of viral diseases. But sometimes, your plant leaves can also turn yellow because of the deficiency of nutrients.

You need to find the exact reason for the yellowing of your plant leaves. After that, you can deal with the problem according to the conditions.

I hope you find this post helpful. If you like this post, don’t forget to share it with your friends.

Moiz Atiq.