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Major Gardenia Pests and Problems

I love gardening and enjoy giving advice on how to take care of difficult plants.

Gardenia Bloom.  Photo by Jill Lang/Dreamstime.

Gardenia Bloom. Photo by Jill Lang/Dreamstime.

Issues Affecting Gardenias

Gardenias are a prevalent flowering plant for many gardeners. Their popularity is due to the beautiful blooms and scents that these blooms produce. Unfortunately, these plants can be tough to care for. So many things can go wrong, and after one plant fails, a gardener may give up on raising them all together. However, there are simple ways to deal with the problems that crop up in caring for these plants. So if you are a gardener that wants to try raising these plants, or you want to give these plants another try, here are the most common issues affecting gardenias:

  1. Gardenia pests
  2. Yellow leaves on gardenia plants
  3. Gardenia bloom problems
  4. Brown leaves on gardenias

1. Gardenia Pests

One of the biggest problems for gardenias is the pests that plague them. The major pests (and how to identify and treat them) include the following:

  • Aphids - One of the most common pests in the garden on all types of plants. These can be treated by spraying plants with a soap solution (one tsp of liquid soap to one gallon of water). Don't forget to spray on the underside of the leaves as well.
  • Mealy Bugs - These can be treated by spraying the plant with a soap solution or using a fine horticultural oil sprayed on the tops and underside of the leaves and plant.
  • Scale - Can be treated with horticultural oil.
  • Root Nematodes - There is no cure for plants infected with nematodes. If your plants have wilted yellow leaves and don't respond to the suggested treatments for yellowing leaves, your plant may be suffering from nematodes.
  • Spider Mites - These can be identified by shaking leaves onto a white sheet of paper, folding the paper in half, and pressing the sides together. When you open the paper back up, check for red smeared spots. These spots are spider mites. They can be treated with Neem.
  • Whiteflies - These small white flies collect on the underside of the plants' leaves. Remove infected leaves and any plants that are infested. Treat the plants with Neem.

2. Yellow Leaves on Gardenia Plants

Next to common garden pests, yellow leaves are the second biggest ailment of gardenia plants. Three things will cause yellow leaves on your plants.

  1. Cold temperatures. Gardenia plants don't like being outdoors in temperatures below 60 degrees Fahrenheit. If you live in a climate where temperatures dip in the evening or at other times of the year, consider keeping your plants in pots that can be moved indoors.
  2. Drainage problems. Gardenias hate having "wet feet." If their soil isn't well-drained, their leaves will turn yellow rather quickly. To remedy this problem in potted plants, place the pots up on marbles, so the pot base is never sitting in water. Plants in the ground may need to be moved when they are dormant.
  3. Soil problems. Add a soil acidifier. Use azalea fertilizer, blueberry fertilizer, or MirAcid. Outdoor plants can benefit from pine bark mulch.

3. Gardenia Bloom Problems

1. Blooms won't open - Nothing is more frustrating to a gardener than when spring arrives, and the gardenia blooms are hard and won't open. This problem can be solved by doing the following:

  • Check the soil pH - It should be between 5.0 and 6.0 (slightly acidic). Adjust the soil if necessary.
  • Proper drainage - Make sure your plant doesn't have "wet feet."
  • Temperature - These plants need warm temperatures to bloom. Bring your plants indoors if they are in pots when the temperatures dip below 60.

2. Bloom drop - This usually happens when a plant is moved right before or when the plant is blooming. Plants should only be transplanted after they have bloomed for the season.

3. No blooms - It happens when you prune a plant too late in the year. The best time to prune the plant is right after the blooms die for the season. Be sure to know what type of gardenia you have before you prune; some varieties bloom twice in a season.

4. Brown Leaves on Gardenias

Brown leaves or brown spots on leaves are usually caused by the following:

  • Water splashed on the leaves when watering the plant
  • pH of the soil is wrong
  • Pests on the plant
  • Not enough sunlight (these plants need 6 to 8 hours of full sunlight each day)
  • Not enough humidity (this usually occurs with house plants)
  • Poor drainage (check to see if your plant has "wet feet")

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Charlotte Gerber (author) from upstate New York on July 20, 2011:

Hi Kathy, I think the nursery worker was correct. Gardenias don't like to have their "feet" wet and will develop yellow leaves as a result. Sounds like you have the problem under control with the corrected drainage. Your plants should rally by the end of the summer at the latest.

Charlotte Gerber (author) from upstate New York on July 20, 2011:

Hi Nancy, Once a gardenia has blooms set you cannot move the pot. Gardenias are sensitive to any kind of change when they are about to bloom. I'm guessing this is the reason that you're experiencing bloom drop. Check out my section above under "Gardenia Bloom Problems" for more information on other causes.

Kathy L on July 15, 2011:

My Gardenia was turning yellow and the nursery woman said to check the drainage. It was sitting in a puddle. We dug it up, made the hole a lot bigger, put in a bag of red pumice topped it with dirt, and replanted the gardenia. What are the odds it will make it? Any gamblers out there? Does anybody have a better idea?

Nancy on July 01, 2011:

I have a problem with my gardenia. It is in a large pot. It is healthy looking. However, it buds that look like they are just about to bloom and then they fall off before they have a chance to open fully. What am I doing wrong?

Charlotte Gerber (author) from upstate New York on March 28, 2011:

Hi Simon, I'm sorry for the delay in responding - perhaps you've remedied the situation by now. Since you're using raised beds, drainage may not be your problem. However, you didn't mention any cold weather, which can cause the leaves to turn yellow. The only other problem may be soil- have you tested it yet? You can get an inexpensive soil test kit at local retail gardening centers or nurseries. If the soil pH is the problem, adding a soil acidifier (usually the cause of yellowing leaves), also available at local retail gardening centers, may remedy the situation.

Simon on March 02, 2011:

Hi, I have a problem with ground planted Gardenias in a raised box. The box is well drained but two of the plants have developed brown shrivelling leaves. It starts with yellowing/browning of the leaves along their centre lines and spreads outwards until the the leaf is dead and shrivelled. On one plant one trunk has died back completely so I cut it out. I found the centre of the trunk is dead (brown) wood. Is this a sign of "wet feet", acidity imbalance or possibly root nematodes? It would be a shame to have to remove both plants. Also what are the odds of the nematodes (if that is the problem) appearing on the other shrubs in the planter? More importantly is there anything I can do to prevent this?

Charlotte Gerber (author) from upstate New York on February 18, 2011:

Hi Bell, If this problem just occurred, your plant probably isn't dead, just terribly unhappy. There will be leaf drop if the leaves have turned brown. Water the plant each day (down by the roots) until the heat wave subsides, then water several times a week (with moderate temperatures). If the plant(s) were healthy before the heat wave, they should bounce back, though it may take several weeks to see a marked improvement due to leaf loss. To tell if the soil is dry, the easiest way to tell is to stick your finger about an inch into the soil (below the mulch). Also, water your plants early in the morning or in the evening after the sun has gone down so it gets the most benefit from the watering.

Bell on February 15, 2011:

My gardenia has brown leaves after a heatwave...I've been water it lots, how do I know if I've watered it too much or not enough? Is there a way to tell if it's dead?

Fraser Soul on August 14, 2009:

Thanks for the very informative article on raising gardenias. I love the way they smell and will look to add them to my garden. Good information on treating pest in the garden.

Jill on July 25, 2009:

Thanks for using my photo!

Gardenias are not the easiest to have around. Mine tend to get scales on them. Just make sure you check this plant/shrub for bugs... it seems to attract them.

Research Analyst on September 25, 2008:

thanks for the informative hub, I have been growing a flower garden and looking to add some new flowers.