If your Gardenia’s leaves turn brown or display brown spots, this may be caused by any of these reasons: Water splashed on the leaves when watering the plant. Drip-irrigation will keep water off the foliage and flowers and prevents leaf spots. Poor soil drainage: Make sure your Gardenia soil is moist but well-drained.Click to see full answer. Simply so, why are my gardenia leaves turning yellow and brown?If your Gardenia’s leaves turn yellow and drop, aside from the normal aging process of its leaves, this may be caused by any of these reasons: Over-watering or under-watering: Gardenias need at least 1 inch of rain (or equivalent watering) each week. Don’t let the soil dry out and don’t over-water your Gardenias.Beside above, how do you revive a dying gardenia? Analyze the soil for both indoor and outdoor gardenias to make necessary adjustments if irrigation, fertilization and moisture are damaging the roots. An overdose of fertilizer leads to too much salt in the soil. Too much water drowns the roots. Water the gardenia only after the top inch of the soil dries out. Subsequently, question is, how do you get rid of fungus on gardenias? To eliminate and control severe infections, use a combination of pruning and insecticide treatments. Rinse the gardenia’s foliage and stems with soap and water to rid them of the fungal layers and wash away the insects that have taken shelter in the gardenia.How do you keep gardenias from turning brown? How to Preserve Fresh-Cut Gardenia Handle the gardenias while wearing garden gloves and only holding them by the stem. Place the gardenias into a plastic container that offers ventilation holes to allow air to circulate. Fill a vase with fresh, cool water and place the gardenias into the vase. Avoid placing the flowers in direct sunlight.