Gardenia Bulb Turning Brown

Spotting Rot Damage

• Brown tubers suffer from a soil-borne fungus called Phytophthora (Phytophthora spp.). The brown color stems from infection as the fungus proliferates across the tuber. In severe cases, fungi travel up the plant's stem and into the limbs and foliage. You may notice that limbs appear brown to black as leaves wilt and flowers fail. Because the brown tuber is hidden within the soil, fungal blight is often difficult to fight once you notice it on the limbs. Spraying the above-ground parts of the plant with fungicide does not eradicate the entire infection. You need to remove the plant before others nearby become infected.

Rejuvenating Your Plant

• If your tuber is only partially brown, you can rejuvenate the plant by removing the unhealthy portion. Once you remove the plant and dig the tuber from the ground, rinse it and inspect the damage. Using a sharp, clean blade, cut away the brown portion. Do not cut into the fungal infection itself, but start in the healthy portion adjacent to the damage. You do not want to infect the tuber any further by transferring fungi spores. A tuber that can potentially grow again has at least three eyes, or buds, left on the healthy portion. Once it's divided, plant the peony gardenia again to encourage nutrient and moisture absorption for healthy root growth and establishment.

Location Consideration

• Choose a full sunlight location for your peony gardenia, especially because its foliage turns from green to purple as summer moves into autumn when the plant is fully established. Unlike other bulb plants, peony tubers do not require a deep planting. In fact, the buds should face upward at only 1 to 2 inches deep. Sprouts growing from the buds have a chance to quickly access sunlight and begin photosynthesis. Do not crowd your tuber with other plants. Once fully established, peony gardenias need good air circulation around their limbs and moist soil to avoid rot issues at the tuber level.

The Way to Water

• Maintain moist soil conditions during the spring, summer and fall. Your peony gardenia benefits from slightly dry soil in the winter to prevent brown and rotting tubers during its inactive growing period. Soil should be friable, to allow roots to absorb moisture while avoiding waterlogging issues. If possible, use a drip irrigation system around your peony gardenia to accurately control water amounts at the soil level. Wetting the foliage and flowers with overhead watering leads to possible disease and dieback.