Primarily found outdoors in the south and grown for their fragrant flowers and handsome foliage, gardenias (Gardenia augusta/Gardenia jasminoides) are popular ornamental shrubs, which are known for their finicky needs. In fact, in some areas, gardenias require considerable maintenance.
Outdoor Gardenia Care
Gardenias are cold-sensitive and may die during severe winters, therefore, gardenias are typically grown outdoors where the winter weather is reasonably tolerable, or grown in pots and moved indoors for winter. Fall or spring is the most suitable time for planting the gardenia bush.
As for outdoor gardenia care, you should keep in mind that when the gardenia plant is grown outdoors, it generally prefers to be kept in partial shade. Gardenias also prefer moist, but well-drained, acidic soil with plenty of organic matter. Water gardenias regularly, even once the plant has finished putting out blooms. Prune the gardenia bush after flowering has ceased to remove spent blooms and untidy branches and to keep the plant in good condition.
Healthy gardenia plants are better able to withstand winter weather and will oftentimes come back stronger in spring.
Indoor Gardenia Care
The gardenia plant can also be successfully grown in containers and treated like houseplants indoors. However, when growing a gardenia bush indoors, you must keep in mind that it requires bright light and high humidity.
The dry, short days of winter will likely be the most troublesome, especially if the gardenia bush is not given enough humidity. Moving plants to southern facing windows and/or supplementing them with grow lights are good ways to improve light conditions during winter.
High humidity is essential to indoor gardenia care. Dry air will quickly cause the flowers to begin dropping from the plant. There are several ways to increase humidity in the home, including the use of a humidifier or grouping plants together on trays of wet pebbles. Misting the gardenia plant is not recommended, as this may cause problems with fungal leaf spots.
The soil, which should be loose and organic, should be kept moist, but take care not to overwater. Monitor the soil frequently for moisture and water thoroughly as the top inch (2.5 cm.) of soil dries. The gardenia plant should also receive cooler nighttime temperatures and warmer daytime temperatures.
When to Fertilize Gardenias
Gardenias require frequent fertilizing to ensure healthy plant growth. Fertilize monthly between April and November using a fertilizer that is specifically formulated for acid-loving plants. Be careful not to over-fertilize gardenia plants. Too much fertilizer can lead to salt accumulation, which can damage the shrub. Do not fertilize gardenias in the fall, which can stimulate growth. This tender, new growth will quickly die when exposed to cold winter temperatures.