Gardenia Plant Problems

Summary: Below are a series of Gardenia problems homeowners may experience.

Related: Brown tips on indoor plants

Gardenia Leaves Turning Yellow

The Gardenia plant (Gardenia jasminoides) produces fragrant flowers and handsome foliage making it a great addition to any garden. However, maintaining gardenias is not an easy task and mishandling would put it at risk of dying. Yellowing and dropping of Gardenia leaves have several possibilities… from a nutritional deficiency, low humidity and over watering.

Yellowing Leaves From Nutritional Deficiency

1 – If you plant has a magnesium or iron deficiency, growth may become retarded along as the leaves turn yellow or discolored.
2 – Gardenias in need of fertilizing, will exhibit symptoms of no buds or dropping buds, yellow leaf spots or yellowing at outer leaf edges and moving inwards, pale bleached look, dropping older leaves.
Same as above – If there are no flowers or buds – feed the acid-loving plants with an acid fertilizer. No feeding while the tree blooms or during winter.

Massive Leaf Drop and Yellowing Leaves

When leaves begin yellowing in mass followed my leaves dropping, the problem often is watering – Too Much water.
If leaf curl, tips turn brown, dieback occurs and the soil is constantly wet. The plant should be removed from the pot immediately. Check the root ball for health, make sure pot drainage holes are not plugged.
Checking The Roots:

• White healthy looking roots – remove all bad foliage, put back in pot and fix watering issues or repot into fresh new soil.
• Roots damaged and partially brown – remove bad roots, repot in fresh soil
• Roots mushy and brown – discard plant

Gardenia Leaves Yellowing From Low Humidity

The symptoms of low humidity show up as: flower buds dropping, leaf tips turning brown, yellowing foliage, gardenia flowers turn brown.
Place the potted gardenia in a tray or bed of moist pebbles. DO NOT allow the pot and roots to sit in water. Spray/mist once or twice per day. In winter use a humidifier.

Gardenia Bud Drop

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. If unsure of the soil pH, gardeners usually conduct a soil test.

New Plant Bud Drop

If the buds on a new gardenia plant turn to black and drop off the issue could be all environmental. Plants moving from a nursery environment to a garden center and then to the home could “shock” the plant as it is acclimating to new surroundings: low light, warm temperatures in the home, low humidity can all contribute to bud drop. Spray-mist on a daily basis, place plant on a try of pebbles to increase humidity.

Sooty Mold

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: One “type” of sooty mold is caused by an air borne fungi. These pests usually appear 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: What causes a sooty, black film on the leaf surface of gardenias?
Answer: This is the “other type” of sooty mold. This sticky secretion on gardenias is caused by white flies which may be controlled with an horticultural oil emulsion spray. Syringe plants with water a few days after to wash off the dirty film. Privet and lilac are also attacked by these pests. Other pests that may infest the gardenia plant include spider mites and aphids.

Water & Spraying

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 peat moss and rotted cow manure over a well-drained soil is advantageous. For healthy gardenia plants, keep the soil moist but don’t over water to avoid root rot.

If confined in a container, a 5-10-5 slow-release 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.

Propagation

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.