The iconic creamy white gardenia blooms are the plant’s main attraction, so it’s disturbing to see the flowers suddenly turning brown or becoming riddled with brown spots.
In such times, you might rightfully wonder whether the browning of the blooms is caused by diseases, pests or other environmental factors?
Unfortunately, all these things can have a role in causing a degradation or discoloration in your gardenia’s flowers.
But rest assured that these problems can be overcome, and new blooms can be prevented from turning brown.
Below, I’ve created a hopefully exhaustive list of the reasons why gardenia flowers turn brown and the remedies to this issue:
Gardenias enjoy full sun or partial shade, with the caveat that in partial shade, the plant should still receive direct light in the first half of the day.
When grown in the shade, gardenia flowers have bad blooming outcomes. Blooms can insufficiently develop, turn yellow or brown, and eventually fall off prematurely.
A gardenia plant that receives 6-8 hours of direct sunshine per day is also less likely to develop fungal problems that can also cause blooms to turn brown.
Therefore, when choosing the ideal location for your gardenia, make sure it doesn’t get shade from nearby plants.
While you can move potted gardenias wherever you please, a gardenia planted outside will be more difficult to relocate.
Also, it’s generally better for gardenia plants to receive full sun in the first half of the day and partial shade during the hottest part of the day.
While they do enjoy basking in the sun, very strong direct light can burn the blooms and leaves as well.
Gardenias enjoy damp, moist soil and don’t tolerate their soil drying out. When grown in dry soil, the blooms start drooping and browning until they eventually fall off.
Therefore, keep the soil moist around the shrub and be careful to keep water off the leaves and blooms when watering to avoid fungal problems.
Overwatering is also a bad idea, especially for potted gardenias that might not be planted in a fast-draining potting mix.
For gardenias kept outdoors or planted in the garden, you can put a layer of mulch around the base to help retain moisture and reduce fast evaporation.
Use soaker hoses and deep irrigation systems to prevent water from getting onto the leaves and blooms. Your gardenia plant will be thankful for it.
You may know that gardenia plants are notoriously difficult to grow. They’re sensitive to a bunch of things and high night-time temperatures is one of the issues that these plants will simply not put up with well.
Gardenias enjoy warm, sunny days and cooler night temperatures of around 60 F. When night-time temperatures are above 60 F, gardenia flowers turn brown and drop off.
To ward off such issues, it’s a good idea to plant gardenias far from pavements, patios, and buildings that naturally retain heat.
Therefore, plant gardenias somewhere in open space, where there’s no risk of nearby structures giving off heat during the night.
Soil pH Issues
For a thriving plant and optimal bloom formation, gardenias enjoy slightly acidic soil in the 5.0 and 6.5 range.
Imbalances of soil pH, i.e. soil that’s too acidic or too alkaline, can adversely affect the blooming process and even cause premature bloom loss.
You can assess the pH level of your gardenia’s potting mix or the soil in the garden to see if it falls within the optimal range for gardenias.
If you find that the soil is too acidic, you can amend the soil by adding garden lime to the mix. If it’s too alkaline, you can use a soil acidifying mix to bring down the pH value to the acceptable range.
In terms of the quality of the soil, pH value isn’t the only metric to go by. Nutritional deficiencies caused by the depletion of nutrients in the potting mix can also result in poor blooming outcomes including browning and premature bloom loss.
While you can easily assess the pH value of the soil, you can’t easily pinpoint the nutritional deficiencies in your potting mix.
Therefore, use a potting mix rich in organic matter and fertilize your gardenia plants with a balanced fertilizer that’s enriched with minerals.
Don’t overdo the fertilizing, which can cause fertilizer burn and adversely affect not only the blooms and foliage of your gardenia plants, but the plant’s lifespan as well.
Beyond temperature differences that aren’t within the optimal range for gardenias and light issues, other environmental stressors like repotting or transplanting your gardenia from one location to another are very likely to cause gardenia blooms to either turn brown or fall off.
This, of course, if the repotting or transfer is not done correctly or in the correct season. Don’t do any repotting in late spring and summer, when buds appear, or the plant is already in full bloom.
Repot only in early spring to prevent damage to the blooms and potential bud blast.
Insects & Diseases
Pests and diseases that attack the blooms can also cause them to turn brown or brown spots may appear as a result of pests or insects damaging the buds or blooms.
Of all the pests, mites can be a common problem as they often damage the tips of the buds causing them to turn brown.
Fungal diseases are another potential issue that can affect not only the leaves of the plant, but the blooms as well.
Insecticidal soaps and anti-fungicides can help treat and prevent pests, insects and fungal diseases from wreaking havoc in your gardenia plants.
Whether it’s something in the way you position your gardenias or the care you afford them, browning blooms can have multiple underlying causes.
Go through each point in this list to try to identify the problem and apply the remedies I suggested to prevent further bloom from turning brown.
Sometimes, multiple things come together to cause flowers to turn brown, so make sure you account for every potential issue.