Gardenia Plant Turning Black and Leaves Falling Off

I am taking care of my sisters Gardenia plant and when I went to check on it today the leaves are wilting and turning black and falling off. Her land lady also checks on it and she fills the mister when the water runs out. My sister is in the hospital and has been in there since September. I have asked her landlady to leave it alone but I am not sure what is going on can you please help me save her plant. Thank you in advance. Paula

Dear Paula,

Gardenia Plant Has Black Spot Disease: There are several things that can cause black leaves and leaf drop on a gardenia plant, Gardenia jasminoides; but from your description, I think it sounds like Black Spot disease. Black Spot disease (Diplocarpon rosae) is a type of plant fungus. It usually attacks the lower leaves of the plant first, then moves upwards on the plant causing leaf drop and black spots all over the leaves. The best way to treat Black Spot disease is to remove all of the infected leaves and any leaves that have dropped onto the soil; keep the leaves dry at all times (stop misting the plant), provide good air circulation around the plant; and spray the plant with a commercial plant Fungicide. You canals use Neem Oil which is an organic, non-toxic, alternative for treating Black Spot disease. Whichever product you choose, spray your plant every 7-10 days during the warmest part of the day since the fungus is most active when the temperature is between 75° to 90°F. Keep your plant away from your other plants.

If the the condition gets worse, you may have to cut the plant down to just above the soil line and have it regrow. After you prune it all the way back, spray what remains with the FungicideLearn what fungicides are and how they are used to treat fungal and bacterial plant infections. or Neem OilLearn about Neem Oil, a natural, organic, non-toxic product for treating houseplant insects and diseases..

When healthy and being cared for properly, a gardenia plant gets lovely, beautifully scented, waxy, white flowers surrounded by green, glossy leaves. But a gardenia is a very temperamental plant and quickly deteriorates if the conditions inside do not mimic its outdoor growing conditions. This is a plant that needs a fertilizerPlants need fertilizer only when they are actively growing. Slow growing plants in low light require very little plant food. Too much fertilizer is worse than not enough. Most plants prefer a water soluble plant food at 1/2 the recommended strength. Plants that are in bloom or dormant should not be fertilized. Houseplant food contains nitrogen (N), phosphorus (P), and potassium (K). A fertilizer containing these elements in equal proportion is considered a balanced plant food. Nitrogen helps in photosynthesis and encourages the growth of leaves and stems. Potassium and phosphorus also help in photosynthesis and aid in root and flower development. Most fertilizers have trace elements of other minerals that are lacking in the soil but are necessary for good plant growth. Fertilizers have a high salt content. If a plant is not producing new leaves and doesn’t absorb the fertilizer, salts build up in the soil. These salts can burn the roots, discolor the leaves, and cause new growth to be small. and a soil for acid loving plants. The correct temperature is extremely important if you want the plant to flower indoors. The besttemperatures for a gardenia plant is 65°-70°F (18.3°-21.2°C) during the day and  55°-65°F (12.8°-18.3°C) at night ((10° cooler). Cool night temperatures are essential for the buds to set. Gardenia buds drop off if temperatures go above 70°F (21.1°C). You can read all my tips on how to care for a gardenia plant at:

https://www.houseplant411.com/houseplant/how-to-grow-and-care-for-a-gardenia-plant