Gardenias are most known for their fragrant, sweet white flowers, but gardeners also prize them for their glossy green leaves. You may grow them as either ornamental shrubs in your outdoor garden or as houseplants. Whatever their environment, your gardenias may occasionally experience health problems and need troubleshooting to fix such problems and restore their health.
Water the gardenia shrub if its foliage shows symptomatic signs of drought stress, including curling or wilting of the leaves and weak stems. The shrubs are only moderately drought tolerant, according to the University of Hawaii, and thrive best when kept consistently moist. Water once a day or whenever the top inch of dirt feels dry to the touch, using enough irrigation to moisten the dirt to a depth of 1/2 foot.
Test your gardenia's soil with a soil pH testing kit if you notice a lack of flower bud development or yellowing of the leaves known as chlorosis. These are signs that the soil pH isn't right, according to Michigan State University, which recommends a pH ranging between 5.0 and 6.0 for gardenias. Ask your regional cooperative extension office what soil amendments, like lime or sulfates, are used in your area to change dirt pH levels.
Fertilize the gardenia shrub once a month if the plant's growth appears stunted or if blossom production is poor. The University of Rhode Island recommends monthly fertilization with any acidic fertilizer labeled for use on gardenias or azaleas, but only during the growing months between April and November.
Inspect the gardenia for pests if it suddenly becomes wilted even though all other cultural needs are provided for, or if you notice holes or bite marks in its foliage or flowers. Common pests include aphids and beetles, which may attack both houseplant gardenias and those raised in the garden. If you find bugs on your gardenias, spray the shrub with a horticultural oil or insecticidal spray labeled for use on ornamental plants.