Gardenias are flowering, evergreen tropical shrubs related to jasmine. They sport deep green high-gloss leaves and bloom with cream or white flowers that have a rich sweet scent. The blooms are ideal for cut flowers either left on the stem or floating in a bowl of water. Planted in spring, the perennials bloom from late spring through summer and for an extended season in some areas with optimal conditions.
Gardenias should be planted in a garden in early spring after all threat of frost has passed. If you need to plant or transplant earlier in the season, plant into a container at least half again as large as the root ball and place indoors in a brightly lit spot until it is safe to place outdoors. When planting out into the soil select a sunny to partial shade exposure. Till up the soil well and create a planting hole twice the diameter of the root ball and at least as deep so that the roots are not in any way compacted. Place the plant in the hole keeping the shoulders of the root ball level with the surrounding soil or elevated by an inch or so. Fill loose soil around the hole and press to make good contact with the roots. Create a 2-inch moat with soil around the drip line and water in well, filling the moat several times as the water percolates into the soil. Mulch around the drip line with shredded bark to prevent moisture evaporation.
Gardenias are cold hardy in USDA Zones 8b through 11 and prefer a filtered sun to partial shade exposure daily. They should be planted in a rich, well-drained acidic soil with a pH level between 5.6 to 6.0. Their natural growth form is in a shrub habit reaching 8 feet in height and spread at maturity, so space them accordingly. Gardenias prefer evenly moist soil that is allowed to dry slightly between deep waterings. Fertilize each month during the growing season with a gardenia friendly fertilizer s but at half strength to induce bloom but prevent burn.