Why Your Gardenia Leaves Are Turning Yellow & How to Fix It

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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Yellow leaves on a gardenia plant could be a sign of several conditions, but it is mostly a sign of chlorosis, a common condition where the plant lacks enough chlorophyll. Keep reading to find out why gardenia leaves turning yellow and tips on how to fix it.

Gardenias are very beautiful plants that are grown for their sweet smell and white flowers. They also boast shiny, and emerald green leaves and can be grown both outdoors and indoors. Despite this, gardenias need a bit of maintenance to keep them looking healthy.

Why Do Gardenia Leaves Turn Yellow?

Apart from chlorosis, there are other reasons why gardenia’s leaves are turning yellow, including;

1. Poor Drainage

Although your gardenia plant might be getting the correct amount of water, the soil could be preventing water from draining out in the right way. This could cause a number of plant diseases like root rotting, which is one of the most common reasons why the leaves turn yellow.

Poor soil drainage will also lead to other problems, for example, the development of fungus gnats which can be a nuisance to the plant.

2. Underwatering and Overwatering

These two are the most common issue when it comes to the leaves. For example, overwatering the plant may lead to poor soil drainage, which will, in turn, prevent the roots from absorbing the necessary nutrients required for the plants to thrive.

Generally, gardenia plants will only require approximately one inch of water every week. However, to ensure that you’re always giving the soil the right amount of water, you should consider getting a soil moisture meter.

3. Lack of the Required Nutrients

A plant may be unable to absorb the required nutrients due to a number of reasons, including improper pH. As a result, deficiencies of any of the important nutrients may lead to yellow leaves.

Some of the important nutrients are zinc, nitrogen, magnesium, and iron. For example, yellow leaves with a green branch could be a sign of iron deficiency, while yellow leaves with some green tips could signify magnesium deficiency.

4. Lack of Enough Sunlight

Gardenia plants require the right amount of sunlight to thrive and remain healthy for a long time. Brown or yellow leaves can appear if the plant is either getting too little or too much sunlight. The best way is to plant the gardenia plant in a place where they can get plenty of sun in the morning and partial shade in the afternoon.

5. Improper pH

A Gardenia is an acid-loving plant that requires acidic soil to absorb the required nutrients properly. Since they grow well in a soil pH between 5.0 to 6.5, if the soil pH is higher or lower, the gardenias may be unable to absorb the required magnesium, zinc, iron, nitrogen, etc. This will, in turn, lead to the yellowing of the leaves.

6. Insects

Insects have toxins that enter the plant cells when they try to suck the plant sap. As a result, the leaves will show tiny black spots and become yellow gradually. The mealybugs are among the most common insects that affect the gardenia leaf, including ants, mites, aphids, caterpillars, etc.

You may notice that where there is the movement of insects, yellowing leaves may appear, and this is why you should always inspect the lower surface of the leaves because most insects tend to hang stay there.

7. Diseases

A number of diseases can be the reason gardenia leaves turning yellow. Leaf spots and sooty mold are the most common fungal diseases that can turn dark green leaves into yellow and brown or black.

How Do You Fix Gardenia Leaves Turning Yellow?

1. Check the pH

Always check the soil pH using a meter, and if the pH is in the right range, then it might not be the reason why the gardenia plant has yellow leaves. However, if the pH is higher than 6.5, then you should consider adding some acidifiers to reduce the pH.

You can also make a homemade solution to acidify the soil;

  • You can mix five tablespoons of vinegar into one liter of water then pour the solution around the base of the plant.
  • Sprinkle one cup of coffee grounds around the plant, mix it with the soil, and water the plant.

2. Boost the Nutrients

Applying a good gardenia fertilizer that has magnesium, iron, nitrogen, and other nutrients is one of the easiest ways to boost soil nutrients. Here are other ways you can boost specific nutrients;

  • If the soil has a magnesium deficiency, you can mix one tablespoon of Epsom salt with a gallon of water and add it to the base of the plant.
  • For iron deficiency, apply a quarter teaspoon of iron sulfate or iron chelate to your gardenia plant.
  • For nitrogen deficiency, you can use one cup of coffee grounds.

3. Improve the Drainage

If the pot doesn’t have drainage, create a drainage hole and repot it using good potting soil with great drainage. Ideally, you can also add some vermiculite, perlite, or sand to ensure the soil is drained and the gardenia’s leaves remain dark green.

4. Proper Watering

You need to know how much water gardenia plants need depending on the weather and the soil water-retaining capabilities. However, the average water requirement gardenia plant is one inch of water per week. Ensure the soil is moist but not oversaturated. A good soil condition and potting mix can come in handy to protect the plant from improper watering helping the leaves remain green.

5. Sunlight

Gardenia needs a minimum of six hours of sunlight. Therefore, ensure there is nothing hindering the plant from getting the required amount of sunlight. For example, do not park the car in front of the plant for a long period.

6. Control the Diseases and Insects

For fungal diseases, you can use fungicide or prune the plants to increase the air and light circulation as well as reduce fungus development. Here are two ways you can prepare a fungicide at home;

  • Mix one cup to one quart of water, then spray the solution on the foliage until the leaves are wet.
  • Mix ammonia and water in a 50:50 ratio, then spray the solution to the foliage.

When it comes to insects, you can always use an insecticide.

Frequently Asked Questions (FAQs) on Gardenias

1. How Can I Prevent Gardenia Yellow Leaves?

With proper care, one can prevent gardenia’s yellow leaves in your garden. Here are some tips;

  • Ensure the soil remains acidic
  • Add a nutrient-rich fertilizer
  • Use insecticides
  • Less water more frequently
  • Grow gardenias in a well-drained pot

2. Should I remove yellow leaves from Gardenia?

It is recommended not to remove the yellow leaves from gardenias because cutting them might also lead to the cutting off of flower buds. Instead, you can use the tips above to make sure the gardenias do not turn yellow.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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