Gardenias possess wonderfully fragrant blossoms and lustrous, dark green leaves. With these qualities, they are seen as high-maintenance plants with fairly specific cultural requirements.
I love growing gardenias. They’re one of my favorite plants in my garden, but lately, I’ve noticed that the leaves on my plants have been turning yellow.
At first, I thought it was because I wasn’t watering them enough, but the leaves continued to turn yellow even when I increased the watering frequency. So then, I wondered if it was a sign of something else – maybe I was overwatering them, or the soil wasn’t acidic enough?
After trying what I thought might be the cause, I realized there are a few more reasons for gardenia leaves turning yellow.
Why Do Gardenia Leaves Turn Yellow?
Several problems result from improper growing conditions of the gardenia flower. They are also susceptible to several diseases, insect pests, and other problems, which sometimes cause the leaves turning yellow.
1. Lacks Nutrients
Nitrogen is essential for foliage growth, so the leaves will turn yellow without it. Yellowing leaves can also be caused by a lack of iron, copper, zinc, and other nutrients.
Iron is a key nutrient that helps plants produce the green pigment chlorophyll. Even though iron is rarely deficient in the soil, if the soil has a pH above 7.0, the iron resident in it may be in a form that is not available to the gardenia plant. And, when a gardenia doesn’t get the iron it requires, its leaves will turn pale green and then yellow.
2. Exposed to Too Much Sun
Gardenias like a lot of light, but too much sun, especially during the hotter times of the year, can scorch the leaves and cause them to turn yellow. The blooms of gardenia quickly fade in extreme temperatures from the sun, also known as temperature stress. If temperatures hover above 70 degrees during the day and below 60 or above 65 degrees at night, the plant buds will not form.
3. Suffering from Overwatering
Gardenias also like to stay evenly moist, but too much water can lead to root rot and yellow leaves. If you’re giving your gardenia too much water, the leaves will turn yellow because the plant suffers from waterlogging and needs to dry out a bit.
4. Soil That’s Too Alkaline
Soil too alkaline hinders the gardenia plant’s roots from getting the required nutrients for optimal growth. Gardenias prefer acidic soil, so if it is too alkaline, it can cause the leaves to turn yellow.
5. Not Getting Enough Water
Yellowing leaves can signify drought stress, put, and lack of adequate water. If you need to water your gardenia more, the leaves will turn yellow to conserve moisture. This is especially common during hot, dry weather when gardenias need extra water to stay healthy.
6. Pests infest Gardenia
Pests, such as spider mites or aphids, can also cause gardenia leaves to turn yellow and eventually drop off the plant.
How to Fix Yellowing Gardenia Leaves
You can do a few things to help your gardenia’s yellowing leaves.
1. Watering
First, ensure you’re watering it regularly (once a week at least) and deeply. Gardenias need a lot of water, so if the soil is dry, give it a good drink.
Misting the leaves with water increases humidity, which is also a good idea. Gardenias like humid conditions, so this can be helpful. Just be sure to take advantage of the flowers, as they can blemish easily.
2. Fertilizing
Make sure you’re feeding your gardenia regularly. A gardenia fertilizer high in iron can help yellow leaves. You can also try adding compost to the soil to help improve drainage and nutrients. Also, fertilize monthly during the growing season with an acidic fertilizer.
3. Overwatering
Cut back on watering until you see the soil dry out. Then, water only when the soil is dry to the touch. If you live in an area with high humidity, you may need to water your gardenia more often than usual to keep the leaves from turning yellow. Ensure the soil, particularly if it’s in a pot, has good drainage.
4. Sunlight
Place in an area with bright indirect light – not too much sun or too little. If it’s in a pot, move the pot from its current location or position to a more appropriate one. If the leaves of other plants are blocking the proper sunlight reach, you can trim those leaves off, creating a channel through which the rays can meet your gardenia leaves. If the rays seem too much on the leaves in their current position, change the location to a less sunny area where it will only get what it needs.
5. Pests
Keep an eye out for pests and treat them accordingly. The green peach aphid and the melon aphid feed on the gardenia plant sap using their piercing-sucking mouthparts. These pests hide in clusters on new growth of leaves, stems, and buds. Mealybugs, scale, spider mites, thrips, and whiteflies are other pests that attack gardenia. To rid your gardenia of these pests, use insecticidal soap or neem oil. Follow the instructions on the product label carefully.
6. Diseases
Stem canker, powdery mildew, nematodes, and sooty mold are diseases that can cause the yellowing of gardenia. You can resolve this problem with fungicides like myclobutanil, chlorothalonil, propiconazole, horticultural oil, and baking soda. Other control measures involve the use of sprays of sulfur or neem oil.
How to Prevent Yellowing of Gardenia Leaves
The best way to prevent the yellowing of gardenia leaves is to provide the plant with the proper care. Gardenias need soil that is rich in organic matter and well-drained. They also require regular watering, but you should keep the soil from becoming soggy. Fertilize gardenias every two weeks during the growing season with a high-acidity fertilizer.
If you notice your gardenia’s leaves turning yellow, inspect the plant to identify the cause. Knowing the cause of the problem makes it easier for you to treat it. With proper care, your gardenia should soon look green and healthy again.