Light: Indoors, give gardenias bright light, but avoid direct sunlight, especially during summer. Outdoors, they prefer a part shade location.
Soil: Gardenias are acid loving plants, so they prefer soil with a slightly lower pH. Normal potting mixes with a peat base meet this criterion. When planted outdoors, it's best to test the soil for pH and amend as needed to create ideal conditions for the plant. A teaspoon of agricultural sulfur mixed into the planting hole may help lower soil ph.
Water: Keep soil continuously moist but reduce watering in the winter. Drip irrigation is a good method since it keeps water off the leaves, which can cause fungal leaf spots.
Humidity: These plants prefer a high humidity level, above 60 percent.
For container plants, feed about every three weeks with an acidifyin fertilizer—the type used for azaleas or camellias is a good choice.
Gardenias have no known toxicity for humans, but pets may experience symptoms if any parts of the plant are ingested.