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5 Signs of Overwatered petunias (Step by Step Solution)

Indoor potted petunia showing overwatered signs

In this article, we are going to look at how to revive your Petunia when you have overwatered it.

Petunias are often overlooked when it comes to indoor plants and owners often tend to water them in the same way as they would if the plant were growing in the garden. 

There are some subtle differences in their indoor maintenance and you will also need to learn to recognize the symptoms of overwatering. 

You can revive an overwatered petunia if you act quickly. Remove the plant from its pot and stand it on a sheet of paper for a few days until the root ball becomes dry. Keep it out of direct sunlight while this is taking place. Repot into fresh potting soil after that, and do not water for three more days. 

Once you understand that you have overwatered your petunia, we will look at ways to revive it.

And of course, how to avoid making the same mistake in the future.

Underwatering symptoms versus overwatering symptoms

Strangely enough, the symptoms between these very different problems can seem quite similar to the untrained eye.

That is because, in both cases, the problem starts at the roots which are unable to supply the plant with its fluid and nutrient requirements.

A plant that is too dry will lack the moisture to elevate nutrients to the stems and leaves, while a plant that is too wet will start to drown as the root system becomes saturated.

Both too much water, and too little water, therefore produce very similar symptoms.

With the Petunia, overwatering will quickly lead to flowers being dropped followed by leaves shedding. The leaves and stems will appear soggy. 

In the case of underwatering the leaves and stems become dry and crisp after wilting occurs.

Signs of Overwatered Petunia

There are several signs that will confirm that overwatering is the issue that you are confronting with your Petunia.

Wilting: The petunia will start to sag and generally look sorry for itself. If you look more closely you will see that the leaves are soggy rather than dry which would indicate too little water.

Brown Leaves: The leaves will become brown but will have a damp texture to them. If the situation continues to deteriorate, some leaves will turn yellow and start to drop. 

Edema: This symptom occurs because the cells of the plant are starting to break down and burst.

It can occur anywhere on the leaf but usually is most apparent on the underside of the leaves. Look for watery bumps that have a similar appearance to blisters.

Wet Soil: This is the sign that I always find most obvious. If your plant is showing any of the signs above a quick examination of the potting soil will confirm your diagnosis.

If it is water-laden, you can be sure that overwatering has induced the symptoms.

Root Rot: As overwatering becomes extreme, the roots themselves will begin to rot.

Rotted roots are unable to perform their primary function of transporting vital nutrients up the plant.

You will be able to identify this issue because the roots will turn brown and become mushy.

How to Fix Overwatered Petunias

Quick action is required now that you have identified the problem.  Here are the steps you need to follow to save your overwatered petunia.

Step1: Tip Petunia from Pot

Tip the plant from its pot and allow the excess water to start to drain away so that some air can get back into the soil.

To speed this process, stand the root ball on a sheet of paper and leave it to dry out. 

Expect this process to take two or three days and ensure that the plant is not in direct sun at any stage during the drying process. 

Both the roots and stems will be fragile at this time. If the plant has too much light, it will transpire more rapidly.

At this delicate stage, you want the plant to cling to all the reserves that it has.

Gradually, as the roots dry out, the root ball will start to absorb some air and turn from soggy back to slightly moist.

Some people promote the idea of squeezing the root ball to speed the drying process. I never do that as I feel the risk of damaging the roots is just too great.

Step 2: Trim off Infected Roots

Once the soil has dried out, it is time to think about repotting your Petunia. Before you do that, take a look at the root ball to ensure that there is not rotting. 

Root rot often follows on from overwatering. Healthy roots are firm and white. Roots that have begun to rot, die and turn an orange-brown color. 

At the same time, they lose texture and become soggy. These brown pieces are no longer fit for purpose. 

You should simply snip them away with a pair of scissors until you reach clean and healthy-looking root material again. 

Be sure to clean the scissors after this operation as they could easily transfer disease to other plants.

Step 2: Ensure Drainage Capacity of The Pot

The next thing you will need to do is check that the pot that you petunia is going into has sufficient drainage holes.

A lack of drainage capacity may have been what brought about this problem in the first place. 

If the water has no means of escape, then it is just a matter of time before the root ball becomes soggy and the plant begins to suffer. 

There should be at least one hole in the bottom of the pot, and that should be large enough for you to get your finger into.

Step 3: Repotting Petunia

Next, you will need a good quality potting soil. Petunia’s are not very fussy when it comes to soil quality. 

Don’t reuse any soil that may have dropped off the root ball when you took it from its container. 

Firstly, it is probably still damp, and secondly, it may be carrying pathogens that could further damage your already weakened plant. 

Here are some key points to keep in mind while repotting:

  • You should repot your plant into a pot of the same size as it came out of. You also want it to be sitting at the same depth as it was previously planted.
  • The top of the soil should lie about an inch below the lip of the pot. That gap between the top of the soil and the top of the pot will allow you to water the plant without it slopping everywhere. 
  • Place some soil in the bottom of the container and then drop your plant in to check that you have the depth right. If not, add or remove soil as appropriate.
  • Once you have the Petunia at the depth you want it, then backfill around the root ball with your new potting soil and gently push the soil down with your fingertips. 
  • You want to squeeze out any air pockets but not make the soil too compact or damage the roots as you backfill.
  • Finally, place the pot in a plant saucer but leave the plant in a low light position for another day, or until you can see that it is starting to revive. 
  • After you have repotted your Petunia, don’t be in a hurry to water it in. There is still probably some moisture lingering around the root ball from its near-death experience, and the potting soil is likely to be slightly damp.
  • It is likely that it will take at least three days before the plant will need watering. Once the plant starts to look healthy again, you can move it back into a position that offers more direct sun and you can water it using the method below. 

Although a healthy Petunia requires plenty of direct light, even when you are growing it as an indoor plant, it should be reintroduced to the sun slowly. 

If you move it into full sun too quickly it may well suffer and wilt again because the root system will still not be in peak condition. 

Try placing it in the sun for an hour on its first day after repotting, and then build up over the course of a week. 

By then it should be back to its old self and able to withstand several hours of direct sun each day. If the plant lacks light, it will either produce small flowers or no flowers at all.

How to Water a Petunia 

When grown in their more familiar garden setting, Petunia’s are quite tolerant of dry spells, and you may well get away with watering them as little as once per week. 

Now that you are growing your plant in a container, you are going to need to pay more attention to your watering technique. 

Watering Rules

Always water your plant from the top of the soil but do not water the flowers or leaves. 

If water sits on the upper parts of the plant it lends itself to the production of fungal diseases to which these plants are prone. 

Simply by targeting the base of the plant when watering, you reduce this risk considerably.

Watering Frequency

The best indicator of when to water is by feeling the surface of the soil with your fingers. If it has become dry then it is time to water. 

Far too often, people water just because they think that it is time to do so and with no other indication than that. 

It is the moisture level of the soil that should dictate how often you water, rather than some gut feeling.

Factors Influence Watering Frequency

The reason you check the soil every day is that there are so many factors that will dictate how much water your Petunia requires. 

A larger plant will transpire more moisture and therefore require water more often than a small one. 

If it is humid then the soil will retain water longer than it would if the surrounding air were dry. 

As soil ages, its ability to hold onto moisture deteriorates and the water will drain away faster. 

All of these factors combine to dictate how often to water and they are constantly changing. 

Even something as simple as the amount of sun that falls on the plant can change the speed at which it will use the water available. 

That simple finger check of the soil surface will guide you more accurately than any other method. You will also find that the backs of your finger are more sensitive than the front.

Water Quality

If you have access to rainwater, filtered water or distilled water, then this should be your water of choice. 

Regular tap water will have passed through a chemical process to remove contaminants. It won’t matter if you need to use it from time to time. 

If you use it over a prolonged period, however, those chemicals eventually build up in the soil in the form of salts and they can become detrimental to plant health.

How Much and When to Water

Once you have noticed that the surface of the soil is dry, it is time to re-water. Apply this with a watering can to the surface of the soil until you see water starting to emerge through the drainage holes in the bottom of your container. 

That will serve as an indicator that the plant has received a thorough soaking.

Once that starts to happen, allow the water to drain away completely. Excess water will probably fill the plant saucer. 

When this happens, remove that water so that you are sure that it does not impede the drainage of more water lingering in the soil.

You may need to do this two or three times during the course of a single watering.

Consider the container that you plant your Petunia into. Terracotta pots, for example, are porous and so tend to lose moisture more quickly than plastic or glazed clay. 

This is not a reason not to opt for a more porous pot but you will need to take into account the faster evaporation rate.

What you want to achieve is a consistent level of moisture without the soil becoming waterlogged and this method is the most effective way of doing just that. 

Don’t get bogged down in details as to how often to water or exactly how much to water. Simply rely on that touch test to tell you what your Petunia needs.

Very often, new gardeners lack confidence and so they tend to look to a schedule as a reliable method of watering, rather than trusting their sense of feel. 

Even more experienced gardeners, sometimes water on certain days of the week rather than by testing to see if the water is actually needed or not. The problems that result can be fatal to your houseplants. 

Common Mistakes and Solutions

Watering is one area where it is easy to get things wrong until you understand what you are trying to do. 

Once that happens, you will see how easy it is to get things right and you will wonder why you ever went astray in the first place. Here is a table of some of the most common watering errors.

Common MistakesHow to Avoid Them
Inconsistent wateringThis is a problem that often occurs when you don’t check your petunia’s moisture levels daily.

Get into the habit of feeling the soil at least once a day. 
It only takes a second and is a cheap and reliable method of maintaining soil that is moist but not wet.
Too much wateringDon’t water until you feel that the surface of the potting soil has become completely dry. 

The most common reason that house plants die is that their owners kill them through overwatering and, in a sense, love them to death. 
Wet soilThis problem will occur if there is not enough drainage or if you water when the soil is not dry enough. 

Check drainage holes and feel that the soil is dry between each watering. 

Make sure that you don’t use a potting mix that is too rich in water-retentive materials such as sphagnum moss.
Water on leavesIf you wet the leaves when watering your Petunia, you expose your plant to fungal problems.

These tend to show up as a gray or white powder-like mildew on the surface of the leaves. 

Water at soil level and make sure the top of the plant stays dry.
Water during the heat of the dayThis can be quite an easy mistake to make. When it is hot, your Petunia needs access to moisture.

Watering when hot means that much of the water you supply will evaporate. In other words, your poor plant is competing with the atmosphere.

If you water in the early morning your Petunia will have more time to absorb that water and use it efficiently. This will reduce stress and increase growth. 
Incorrect cultivarThere are many different types of Petunia and many of them have been specifically bred for outdoor cultivation.

When choosing an indoor plant, you should look for varieties that are compact as this will make them easier to manage. 

They will require less water and leaves and stems will not spread as widely making it possible to water the soil without wetting the upper regions of the plant.

Final Words

Grown indoors, your Petunia will provide you with a visually attractive and unusual houseplant. They are easy to look after, but overwatering can quickly become an issue. 

Don’t let this put you off as watering is something that you will master in a short space of time.

Once you have learned how to water correctly by using the methods I have just discussed, you should have a very happy and vigorous plant.

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Thursday 21st of July 2022

Easy to follow and makes complete sense, thank you for this well written article! Now I am going to go save my overwatered petunias!