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Summary: Below are a series of different questions and answers to problems readers have had in growing the fragrant gardenia.

Question: Please tell me how to grow gardenia plants. I buy one every year and it slowly dies.

Answer: Gardenias thrive only in acid soil (Click Here to learn more about acid soil). When repotting use half soil and half acid peak Add some sand if the soil is heavy and sticky. Add one ounce of iron sulfate and one ounce of ammonium sulfate to two gallons of water. Water the plants thoroughly once each month with this solution to maintain the soil acidity and food supply. During August and September omit the ammonium sulfate from the solution. Never use super-phosphates, bone meal, lime or any fertilizer that will neutralize the acidity.

With a spray nozzle on the hose, syringe the plants at frequent intervals. Lack of water during the summer will produce small leaves and a dull green color. From the last of September until after blooming, the temperature should be about 60 degrees which is excellent for nighttime. The higher the temperature, the more humidity will be necessary to prevent bud drop.

After buds are formed, syringing should be cut down, the light increased, and the watering decreased to harden the growth. Cloudy weather and excessive moisture after the buds are formed may cause many buds to drop. In May, prune the plants back to a moderate height and remove the thin wood. Red spider and mealybug are the most troublesome pests. If the foliage has been syringed regularly with plenty of water pressure, these insects will be of little trouble.

Question: I have three large gardenia bushes, about 12 years old. This year there is a black mold on the leaves. How can I rid the bushes of it? CAE, Texas

Answer: Sooty mold is caused by an air borne fungi. It usually appears when plants are chilled or wet frequently and not properly ventilated. Better light, more air, and keeping the foliage dry when watering is the best preventative. A light spray using oil emulsion such as Volck diluted one to 75 will destroy sooty mold fungi on gardenia bushes.

Question: I was told that a gardenia plant needs to be watered every other day and sprayed once a week with malathion. What fertilizer suits it best and how much should be applied and how often? Should it get sun or shade? TZ, Mexico

Answer: The gardenia is a sun lover but some shade during the hottest part of the day is not harmful. It needs water often enough to keep it from getting really dry when growth is active but probably not every other day. A weekly forceful spray of water with occasional sprays of malathion should keep the plant clean and free of insects. If your plant is outdoors, a 2-inch layer of peatmoss and rotted cow manure over the soil is advantageous. If confined in a container, a 5-10-5 fertilizer could be used either dry at the rate of a level teaspoonful to a 6-inch pot or as a liquid at the rate of 2 teaspoonfuls stirred in one gallon of water. Food may be given the plant about every three weeks when growth is active.

Question: What causes a sooty, black film on the leaf surface of gardenias?

Answer: This sticky secretion on gardenias is caused by white flies which may be controlled with an oil emulsion spray. Syringe plants with water a few days after to wash off the dirty film. Privet and lilac are also attacked by this pest.

Question: Could you tell me how to start a new gardenia from an old one?

Answer: Tip cuttings three or four inches long are taken late in the winter and rooted in a mixture of sand and peat. Insert unrooted cuttings in 2-1/2-inch pots, and give them a bottom temperature of 70 to 75 degrees. If kept moist and in an atmosphere that is not dry, the cuttings will root in about eight weeks.

Question: The buds on my gardenia plant get about ready to open, then start to turn brown. What can I do to make them bloom?

Answer: This trouble is referred to as bud drop. The proper culture to prevent bud drop is difficult in a house and often occurs in spite of all precautions in a home greenhouse. Frequent overhead watering after the buds are set may cause them to drop, but lack of sunlight is the chief cause of bud drop. With a uniform temperature of 60 to 62 degrees, good light and high humidity, the chances of bud drop are slight.

A pot-grown gardenia should have a regular application of one ounce of iron sulfate to two gallons of water at least once a month to maintain correct soil acidity. An alkaline soil condition will prevent the buds from opening and is one cause of bud drop.