Causes of Blackening Gardenia Leaves and How to Fix Them

I. Causes of Leaf Blackening

1. Overwatering

If your gardenia leaves have turned black, it may be because you watered too much, causing water to accumulate in the soil, so the plant cannot breathe properly and the roots rot. Of course, the roots are underground where you cannot see them, but you can see the visible sign of the leaves turning black.

2. Root Damage

If the roots are attacked by pests or diseases, they will be damaged. If you water too much at this time, the damage to the roots becomes even more serious, so they cannot transport enough nutrients to the leaves, and the leaves turn black.

3. Temperature Too Low

Another possibility is that the winter temperature is too low. It is suited to growing in an environment of 16 to 18°C. If the winter is too cold, it will stop growing, and with no way for the leaves to absorb nutrients, they will turn black.

4. Pests

Check whether there are insects or eggs on the leaves. If there are, it is very likely that aphids and scale insects have damaged the leaves. If there are no insects, it may also be sooty mold.

II. How to Deal With It

1. First, think about whether you have been watering too much. Generally, this flower should be watered only when there is no moisture left around the soil, and each time you water, the soil should be soaked through. Of course, on rainy and cloudy days you should limit the water.

2. Temperatures that are too low or too high are both bad for its growth, so in summer place it somewhere ventilated with suitable humidity, and provide something to shade it from the sun. In winter, leave it at a temperature no lower than 0°C to let it go dormant. Do not let the temperature get too high, otherwise next year's flowers will grow poorly.

3. If you find insects on the leaves but not very many of them, you can make your own insecticide. If they are aphids, crush two garlic cloves and add water, about 1 L, then spray it on the plant. If they are scale insects, you can remove them with alcohol or use soapy water. If there are a great many insects, buy a specialized insecticide from the market.