Gardenias are perennial flowering shrubs commonly used in landscaping in the southern United States. Hardy in USDA hardiness zones 8 through 11 only, gardenias cannot tolerate cold temperatures. In cooler climates, gardeners often cultivate gardenias indoors in containers. The plants require regular care to thrive, but reward the patient grower with fragrant, white blossoms and attractive, evergreen foliage throughout the year. Gardenias reach up to 6 feet tall, depending on the variety, and create an impressive display in the garden with proper care and maintenance.
Plant gardenias during late spring in a location that receives six to eight hours of direct sunlight each day. Apply a 2-inch layer of peat moss to the planting site and use a garden tiller to work the matter into the soil. Space gardenias at least 3 to 4 feet apart.
Dig a hole in the soil of equal depth and twice as wide as the root ball of the plant, using a shovel. Place the root ball directly in the hole and cover with soil. Water thoroughly to compact the soil and bring moisture into contact with the roots.
Apply a 4-inch layer of mulch to gardenias to insulate the soil and reduce competitive weeds. Begin the mulch 3 to 4 inches from the base of the plant to reduce the chance of fungal infestations and to allow adequate air circulation.
Water once per week during the spring, summer and fall, allowing the soil to dry slightly between each application. Reduce the frequency of watering to once every 10 days during winter, when the plant is growing more slowly.
Fertilize once every two months using a high-nitrogen 12-6-8 NPK fertilizer to provide the correct nutrients for flower, foliage and root formation. Read the manufacturer's directions for application and dosage information.
Prune twice per year, once in late summer after flowering has ended and again in early spring, just before growth begins. Remove excessively long, diseased and damaged limbs to promote a compact and healthy growth habit. Use pruning shears to cut off the limbs as close to their point of origin as possible to minimize damage.