Q&A for How to Care for a Gardenia

Yellow leaves can be caused by an iron deficiency. Add an iron supplement, such as Ironite mineral supplement, to see if that resolves your issue. Follow the directions on the label to dose your soil properly.

Treat for white flies whenever they are noticed. It is best to treat the flies as soon as you see them on your plants to prevent a larger infestation that will be harder to control.

This tends to happen when the gardenia plant as been grown in too much shade. Or, the plant may not have been watered sufficiently; if the gardenia lacks a moist soil or is subjected to too much hot, dry air, this can cause the flowers to turn brown and drop off.

A gardenia bush needs pruning when the bush gets a bit ragged and messy. Prune when blooming has finished, using sharp pruning shears. Take the dead blooms off first, followed by the back shoots. Detailed information on pruning a gardenia bush, with images, can be found here: How to Prune a Gardenia Bush .

Get rid of the insects and the sooty mold should also disappear because they are the source of shifting the mold spores around. You'll need to identify the pest to be able to target it properly; it is usually spread by sap-sucking insects (mealybugs, aphids, scale, etc.), so check not only the gardenia but surrounding plants, to find the source of the insects. Once the plant is treated for pests, the sooty mold should clear up.

Cut gardenia flowers are delicate and don't last very long; the petals bruise easily, so avoid handling them when transferring to the vase. Expect them to be at their best for only 2 to 3 days, after which they'll wilt and die. Keep the cut flowers as cool as possible and mist them often to maintain their freshness.

Spray the tops and bottoms of leaves with an insecticidal soap until they're dripping wet. Repeat this process a few times, waiting a week between each application.

Depending on the variety, a gardenia could grow up to 8 feet (2.4 m) tall outside.

Potassium is helpful to the growth of gardenias, but it needs to be used in proper balance with other nutrients. It will often be found in the acid fertilizers that you can buy and feed your gardenia monthly.