Glossy green foliage and fragrant waxy-white flowers are worth the effort necessary to grow gardenias successfully. Night temperature of 65 F and high humidity must be maintained; drafts and sudden temperature changes must be avoided. Keep soil moist at all times, syringe foliage frequently.
Give full sun. Additional (artificial) light from mid-September will encourage a longer blooming period. Purchase your first gardenia from a florist or garden center. If you are successful in growing it, take 4 to 6-inch tip cuttings to increase your supply. Cuttings, dipped in root-promoting powder, require bottom heat and a humid atmosphere and are best started from December through March, in sand; they should be well rooted in four to six weeks, then they are ready for 2 or 3-inch pots. Equal parts of soil and acid peat plus a small amount of superphosphate make a good potting mix. Soil must be acid. Every two to three weeks, apply 1 ounce of iron sulphate dissolved in 2 gallons of water.
Vinegar (1 teaspoon to a quart of water) also helps to maintain the acidity required. Shift to larger pots as necessary gardenias should not be potbound. About every six weeks use a complete liquid fertilizer in place of the iron sulphate or vinegar solutions. To prevent the bud drop caused by low humidity, syringe foliage and wet down walks frequently during hot weather. Small-leaved large-flowered G. jasminoides Veitchii blooms intermittently through the year.