Gardenia Leaves Turning Yellow

Gardenia leaves turning yellow can ruin the look of your shrub, and the fear of losing your shrub is understandable. Rest assured, though, that there are few problems evidenced by yellow leaves that can indicate serious health problems.

In fact gardenias are notoriously hard to grow and delicate. But what causes leaves on your gardenia turn yellow and how to fix the problem?

Yellowing of gardenia leaves can be a sign of many different problems, from wrong soil pH to excessive moisture in the soil to drought stress. But wait, don’t panic! If your gardenia leaves are turning yellow, quickly analyze the symptoms and apply the correct solution and your prized shrub will turn its leaves back to that splendid deep green and healthy color..

Read on to find what can cause yellowing gardenia leaves, how to recognize and identify the issue behind foliage discoloring.

General Guidelines For Growing Gardenias

General Guidelines For Growing Gardenias

First, let’s check if you are doing everything right with your gardenia; it’s a very demanding but beautiful shrub, so, any mistake with its maintenance or even positioning can cause leaf yellowing and other problems, including the death of your green friend.

Gardenias Need Mild to Warm Climate

Gardenias Need Mild to Warm Climate

You can grow gardenias in USDA zones 6 to 11. They do not tolerate cold climates, because they come from areas of Asia like Vietnam, Southern China, Korea, Taiwan, India, Myanmar, Bangladesh and some mild areas of Japan.

Cold winters can spell disaster with your gardenia; you may even lose it if the temperature drops too much.

It is heat tolerant, to zones 7 to 12 but in hotter regions you will do better planting it in partial shade… Talking about which.

Gardenias Need Fairly Good Sunlight Conditions

Gardenias Need Fairly Good Sunlight Conditions

A gardenia shrub will grow well in full Sun, dappled shade, light shade or partial shade.

In less warm areas, like USDA zones 7 and 8, it will do well in full Sun, while towards 10 to 12 a part shade position is ideal.

If light is too low, your plant will suffer severely. The ideal position for a gardenia is facing east and north (or east and south in the Southern Hemisphere).

This can be really important for the success of your efforts, especially hot areas. This will avoid the strongest and hottest light of the day, as it may burn its leaves;  but still give it plenty of brightness in the morning.

If you grow your gardenia indoors, place it in a bright but indirect light position, with at leas 5 hours of light a day, from a west facing window.

However, gardenias are not “indoor plants”, they prefer outdoor conditions. If you have a gardenia at home, it is more prone to catching disease and poor blossoming.

Gardenias Need Fertile Soil

Gardenias Need Fertile Soil

If the soil is poor, your gardenia will suffer! You won’t get many flowers – if at all – its growth will be stunted and leaves will get all sorts of problems.

This plant needs organically rich loam, clay or sand based soil; if it is chalk based, it will simply die shortly, unless you improve it.

What is more, soil needs excellent drainage. Add lots of sand, small gravel and other similar material if your soil is tough. 

Its roots are quite delicate, it just cannot get through compacted soil.  You can help preserve organic matter and humidity by mulching around the base of the shrub.

Do not leave the soil bare, it will soon compact or become too sandy, depending on its composition, and it will lose lots of nutrients and fast.

And in fact…

Gardenias Need Constantly Humid Soil

Gardenias Need Constantly Humid Soil

You need to water your gardenia regularly. The average a shrub of Gardenia jasminoides needs is 1 inch of water per week through the warm season, either from rain or hosing.

Reduce the watering progressively in late fall to winter, but always calculate rainfall.

Do not overwater though; this will cause lots of problems to your plant, from spider mites to root rot in very severe cases.

On the other hand, gardenias are not drought tolerant. If you leave for some time, get a neighbor or friend to water your delicate plant.

Gardenias Are Acidophilic Plants

Gardenias are very hard to grow because they need acidic soil. The pH should never exceed 6.5.

If it does, you will need to correct it, and we will see how you can do it later on. The optimal pH range is between 5.0 and 6.0. 

When soil impoverishes, it also tends to become alkaline, so, feeding is essential. Which leads us straight into the next point.

Gardenias Need Regular Feeding

In full soil, give your gardenia abundant organic compost in spring and in summer, as it will need lots of nutrients for the vegetative (growing) and reproductive phase (blooming).

Don’t disturb the soil when you feed it. Just scatter the compost on the soil and allow it to filter into the earth, or be taken down by small animals and worms.

And yes, gardenias love worm rich soil! They also aerate the ground, and make it easy for the tender roots to grow and explore…

Do not fertilize in fall and winter. This will disturb its dormancy; even beautiful plants need a rest…

Indoors, use an organic acid based fertilizer with NPK of 3:1:3 or 3:1:2 and make sure that it’s rich in iron. Ideally, use a specific one for gardenias; there are plenty on the market because it is a popular plant. 

Feed your gardenia every two weeks from spring to fall and cut down on your feeding regime to roughly once a month, when winter approaches.

You see, they are very particular about the maintenance you give them, but still, even if you do everything well, “things happen” and your gardenia’s leaves may turn from emerald to yellow… Why? And what can you do about it? Up next…

Why Gardenia Leaves Are Turning Yellow And What You Can Do About It

Why Gardenia Leaves Turn Yellow And What You Can Do About It

Gardenias with yellow leaves are not just less beautiful; they are sick! And there is always a cause; first we need to look at the reason, and once we have discovered it, we can find the solution and even think about prevention in some cases.

Some are connected, and we will see it soon. But now, let’s go through each possible scenario and look at the solutions.

Well, It Could Just Be Natural Aging

How to Understand Natural Leaf Yellowing in Gardenias

There is one natural exception to gardenia leaves turning yellow, and you should not worry about this.

Old gardenia leaves will simply turn yellow and drop. This can happen all year round though it tends to happen more often in fall and winter.

Simple, if you see that the odd leaf of your gardenia are turning yellow and it is not a new one, then you just don’t need to do anything. Allow it its natural course, though you can cut it for aesthetic reasons.

Now, on to the problematic cases…

Yellow Gardenia Leaves Due to Overwatering or Underwatering

How You Can Remedy Yellow Gardenia Leaves Due to Overwatering or Underwatering

Watering gardenias too much or too little is a mistake you should never make. In both cases you may see that the leaves turn yellow.

Don’t get me wrong; the odd excessive watering or the little delay won’t cause any problems. But if this is persistent and prolonged, the foliage of your shrub will suffer.

Overwatering will cause gardenia leaves to turn yellow, and then dark, mustard yellow, and eventually even brown.

The browning will start at the tips and progressively take over more and more of the leaf. This is really severe, and in fact your plant may even have root rot.

  • Suspend watering immediately and add sand to the soil. Wait for some time and if the problem does not improve, look at the next section on root rot. This is a delicate matter.
  • Restart watering after a couple or three weeks, and reduce the amount of water you give each time. Don’t wait too much, the soil needs to become fairly dry but not completely dry. Your aim is to allow pockets of water to empty, not to dry up all the grains of soil.
  • Cut the rotting leaves! They may cause the rot to spread, and attract pests. Also, you will eliminate some of the excessive water from your plant.

In case it is underwatering, the leaves will turn yellow but dry, and they will brown in patches, not as a constant progression from the tip of the leaf. It will also be light in color and, of course, dry. What can you do?

  • Water your plant immediately, but do not give excessive water, just use the correct quantity of 1 inch.
  • Water again a week later; don’t be tempted to give extra watering unless it’s very hot indeed. Check the soil; if the first inch or two are dry, then go ahead.
  • Make sure you keep to the right routine. You can note it in your calendar to make sure you don’t forget. But don’t forget to calculate rainy days…
  • You can remove dry leaves. This is not necessary; they will eventually drop. But if the plant does not look good, please go ahead.

And if things get serious with overwatering…

Due to Root Rot

How You Can Remedy Gardenia Leaves Due to Root Rot

Root rot is a very, very serious problem indeed. You can even lose your plant, and it’s not a rare occurrence, it’s a very serious and probable outcome.

If the plant does not recover in two to three weeks, and even worse, if the rotted yellowing continues, and if it spreads to the branches… You need drastic action.

  • Choose a dry and sunny day. Even if it’s winter, avoid humid days. Better if you start in the morning, you’ll find out why as you read on.
  • Uproot the plant. Yes, we are at this extreme stage. You will need to be careful not to break main roots when you do this. Get your fork and loosen the soil, then use a shovel to dig deep all around the plant; make sure you exceed the drop line, which is the line that goes from the outset leaf to the soil. Slowly remove the whole shrub.
  • Place the shrub on its side on a plastic sheet. Turn the plant slowly and with care.
  • Remove most of the soil. Don’t remove all; you need to leave some, but make sure you can see the roots clearly.
  • Check for root rot. Look at any rotting roots; sings are yellowing, browning or even blackening of soft roots, lacerations in the roots and unnatural swelling of the roots (filled with too much water).
  • Cut all the rotting roots with a sterile blade. Do make sure you cut generously; cut more rather than less. And use alcohol or vinegar to sterilize the blade! Any germs on it will end up straight into your ailing gardenia… 
  • Spray apple cider vinegar on the damaged roots. This will stop pathogens from moving into the roots; it is a disinfectant. At the same time, it will encourage new roots to grow.
  • Allow the plant’s roots to dry for a few hours. With other plants, this can last even a few days. Not with delicate gardenias. Morning to evening is ideal.
  • Totally empty the hole where the gardenia was. Get rid of all the soil, it will contain the pathogens that cause root rot.
  • Sprinkle organic carbonated charcoal all over the sides and bottom of the hole. This will kill the pathogens that cause root rot. A thin layer is all you need. Do not exceed though. You want a healthy soil, not a sterile one!
  • Replant the gardenia with new soil. Make sure it is loose and packed with drainage material. Your plant will need aeration as well at this stage; the roots will need to breathe.
  • Water your plant and compact the soil lightly with your feet to stabilize it. Yes, you do need to water at this stage, but avoid excess.

If the plant is still strong enough, it will survive. But root root can be lethal and in fact we have just seen the worst of all the problems. So, take a deep breath and let’s see more cases…

Does Not Have Proper Drainage

If drainage is poor, you will get similar effects to those of overwateing. So, check that the soil has enough sand, gravel etc. in it, if not…

  • Temporarily reduce watering and spread it over more sessions. Reduce the overall watering by about 1/3 and do it twice a week for the same total quantity. This will allow better flowing of water in the soil. 
  • Add plenty of drainage material to the soil. Sand, coarse sand, gravel, perlite etc. are all good options. A mix is ideal. Spread it all over the top and don’t dig it in… You won’t reach the deep roots anyway; you will only impoverish the soil and risk damaging your gardenia’s roots.
  • Restart the regular watering routine within one month. Now, don’t forget that if it’s a very hot time of the year you will need to adapt your watering, the same if it is very wet.

And from underground to the sky… What happens if the light is wrong?

Excessive Light Can Cause Yellowing Leaves On Gardenia

How to Remedy Yellow Gardenia Leaves Due to Excessive Light

Even too much light can be a problem for your gardenia’s foliage, both outdoors and indoors. The leaves may turn yellow and dry, often accompanied by scorching in this case.

Remember that gardenias like sunlight when it’s fresh, but they prefer shade in the hot hours of the day. So, in case the plant is in your garden, and you can’t move it…

  • Shade your shrub from noon till evening. Do it especially in summer, and it’s easily done with a shading net or any substitute. Even the old sheet you don’t use any more will do!

And if it is indoors…

  • Move your gardenia; make sure it stays at least 8 feet (2.4 meters) from a window, and choose a window that at least does not face south.

That was easy… But how about the opposite problem? 

Yellow Gardenia Leaves Due to Too Little Light

When the light is scarce the leaves will progressively lose color till they yellow. This is a much slower but more uniform phenomenon than with too much sunlight.

They will turn pale green at first, losing that dark sheen they have when they are healthy.

Then, the green will turn to yellow, and at this stage, the leaf may be lost forever. It will also tend to affect all the leaves together, or most of them, or all those on one side of the shrub.

In case it’s indoors…

  • Simply move the pot to a brighter place; your plant will recover pretty fast and safely.

In case it’s outdoor…

  • If the shade is due to moveable structures, like a wood panel, an internal wall, you may consider the option of moving the structure that stops the light.
  • Alternatively, your only option is to move the whole plant to a brighter place. Unless the problem is really severe, wait till fall to do this; that’s the best time for changing their home, and they don’t take too well to transplanting, especially when they are mature, so be very delicate and considerate.

Your Gardenia Got Too Cold

Gardenias fare better at very moderate temperatures: during the day, 65 to 70oF (18 to 21oC) while at night, 60 to 65oF (15 to 18o C).

Any prolonged periods under these may cause leaf yellowing and then dropping.

What can you do if the weather is cooler than expected?

  • Mulch! Mulching raises the soil temperature, and warm roots may just do the trick!
  • Shelter your shrub from cold winds. Sometimes it is just enough to avoid the cooler winds, especially from the north, to keep your gardenia healthy.
  • Cover your gardenia. For more severe temperatures, you will need to wrap it up warm. A plastic sheet with ventilation will do perfectly well, especially if you add some straw at the base of the plant: it will create heat and you will have a mini greenhouse for your delicate shrub.

Of the basic needs of plants, food is very important, and in fact…

Nutrient Deficiency Is A Common Cause Of Leaf Yellowing In Gardenias

How to Remedy Yellow Gardenia Leaves Due to nutrient Deficiency

Yellow patches, maybe accompanied by misshapen leaves, some brown dots etc. are a matter of nutrient deficiency in many cases.

This can have two causes; the first we will look at now, the second later on: poor feeding and high soil pH.

Poor feeding usually happens when the plant is in a pot, or when you use wrong fertilizers, even if organic.

The reason is that these feed the plant but not the soil. Organic matter like compost on the other hand will feed the soil, and this will usually give your gardenia all the food it needs.

  • A common nutrient deficiency with gardenias is iron. In this case, young leaves will turn yellow and sometimes they will have a burnt brown tip. 
  • Manganese deficiency results in patched yellow leaves with dead areas.
  • Sulphur and / or calcium deficiency will produce dwarf yellow leaves. 
  • Potassium deficiency will see your leaves yellowing at the margins and then progressing towards the middle.
  • Phosphorus deficiency gives you a dull shade of yellow in the leaves that grow slowly, old leaves turn dark green and they slowly die.
  • Nitrogen deficiency gives you yellowing that starts from the margins in young leaves, and from the midrib in older leaves. The leaves become crippled and wiry and this usually starts from the bottom of the plant.

You can see that there are very detailed symptoms, but don’t hurry to give them exact minerals yet! There are much simpler and easier ways!  

As a general rule, try to have a healthy and living soil, using leaves, compost, worms, avoiding chemicals at all costs.

Make sure that it’s not compacted and make sure that it has thriving organisms in it. With conditions like these, the soil will give the right nutrients for your plant. 

But sometimes we can’t do this; you may have pollution from a neighboring garden or street. You may have a small plot of land… 

So…

  • Switch to a gardenia (and camellia) specific fertilizer. Don’t over-fertilize though. Even too many nutrients will cause problems. It will take some time, but as your plant starts metabolizing the right nutrients, it will pick up again. It may take over a month though.
  • Switch to compost if you can. 
  • Check the pH of the soil! Because it it is too high, then you can sort everything out by fixing it.

How? Read on and you will find out.

High Soil pH

As a acid-loving plant gardenia grow best in soil with a pH of 5.0 to 6.0. but when the pH goes past 6.5, gardenia leaves will become yellow (chlorotic) due to iron deficiency caused by alkaline soils.

Let me tell you why, because it is connected with the previous section…

Wrong pH causes malnutrition in plants. They eat too much of some nutrients and too little of others! 

Each pH level increases the absorption of certain nutrients and decreases that of others. The result is that the plant won’t get the exact balance of nutrients that it needs, as is shown in this picture.

2022-04-02

This has nothing to do with how much of each nutrient they have in the soil. So, if you fertilize with the right balance, you won’t get any results if the problem is the acidity.

The roots of plants absorb more or less of each individual nutrient according to how low or high the pH is. 

So, if the pH is too high, you need to correct the soil’s acidity. Do this also as prevention,

especially if your soil is naturally in the neutral or alkaline range; even if you use acidic soil for your acidophilic plants, it will automatically tend to revert back to the original pH.

But how?

  • Do not use chemicals. They are too aggressive and harsh and they kill the many little organisms that are your gardenia’s best friends.
  • Fresh coffee grounds lower soil pH. You can’t use them with most plants, but with gardenias they are perfect!
  • Give some tea to your gardenias. Yes, they like a “cuppa”! whether you give them a real cup, or cold tea or tea leaves it’s fine, as long as it is black tea, which has acidic pH. Green tea is very alkaline, don’t get mistaken!
  • Orange and lemon peels added to the soil regularly can help keep the pH low. Don’t add them to your compost though. Reserve them for the feet of your gardenia.

Feeding gardenias may be more fun than you thought!

  • If your soil is very alcaline, you will need to correct the acidity regularly, as it will tend to turn back to a high pH level. Alternatively you can isolate your gardenia from the rest of the soil when you plant it, as prevention.
  •  Dig a large hole where you want to plant your gardenia. This should be at least 8 feet in diameter (2.4 meters) and 5 feet deep (1.5 meters). 
  • Line the whole hole with an impermeable sheet (like plastic).
  • Pierce holes in the bottom of the sheet. This is to allow drainage. Not at the sides though.
  • Place a layer of coarse sand and small gravel at the bottom, or other draining material. This should be about 8 inches (20 cm).
  • Fill the hole with loose acidic and organically rich soil.

It is a large scale and demanding operation, but it is worthwhile if you have unsuitable soil and you really want a gardenia. In fact it’s what professional gardeners do in parks with alkaline soil.

Gardenia Leaves Turning Yellow: Problem Solved!

Gardenia Leaves Turning Yellow: Problem Solved!

Yellow leaves on gardenias look bad and they can be a health problem. Sometimes it is not too serious and you can find an easy solution for it.

Other times it can be life threatening for your shrub, and you need to act fast and even drastically. On the other hand, some solutions are cheap and even fun, so, well, now you know them too. 

The good news is that whichever is the cause, there is a solution and we have written the all round, complete and ultimate guide to curing gardenias whose leaves are turning yellow for you.

It’s all here, in this article, laid out plain and simple but in detail for you. Earmark this page, because if you have a gardenia the chances are that you will come back again!

Adriano Bulla

Written By

Adriano Bulla

After many years as an academic in London, Adriano Bulla became a writer, publishing books like A History of Gardening, Organic Gardening and Elements of Garden Design; he then decided to become a gardener, following his childhood dream, and has been following his dream writing and gardening professionally in Southern Europe, where he has specialized in new and innovative organic gardening fields and techniques, like permaculture, regenerative agriculture, food forests and hydroponics.

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5 Comments

  1. Avatar photo Gail Slawson says:

    This site is interesting but confusing. There are too many options to chose from and not enough information on how to solve the problem!

    Reply

  2. Extremely informative. Was looking for this exact information. Thanks!!

    Reply

  3. Didn’t know gardenias needed iron. My gardenia is beautiful since I added iron. Sometimes I add epsom salts when I do not have iron and it seems to be growing well. This year I had 40 flowers at one time!

    Reply

  4. Wish I could send pic. These r new shrubs. And looked great u til
    A few days ago. From
    The article I believe it is nutrients

    Reply