Hoya plants are hardy and easy to care for, but they can still experience issues like dropping leaves. If you notice that your Hoya plant is dropping leaves, there may be several reasons for this, including overwatering, underwatering, pests, and environmental factors. Here is a detailed guide on why your Hoya plant may be dropping leaves and how to solve it:

1. Overwatering: Overwatering is one of the most common causes of leaf drop in Hoya plants. When the soil is too moist, it can lead to root rot, which can cause the leaves to turn yellow and drop off. To solve this problem, allow the soil to dry out between waterings and make sure that the pot has good drainage.

2. Underwatering: Underwatering can also cause leaf drop in Hoya plants. When the plant is not getting enough water, the leaves can become dry and brittle, which can lead to leaf drop. To solve this problem, water the plant more frequently and ensure that the soil is moist but not waterlogged.

3. Pests: Pests such as spider mites, mealybugs, and scale insects can also cause leaf drop in Hoya plants. These pests can damage the leaves and cause them to turn yellow or brown before they drop off. To solve this problem, isolate the plant and treat it with an insecticide that is safe for Hoya plants.

4. Environmental factors: Environmental factors such as temperature, humidity, and light can also cause leaf drop in Hoya plants. Hoya plants prefer bright, indirect light and high humidity, so make sure that the plant is getting enough light and that the air is moist enough. If the plant is exposed to cold drafts or sudden changes in temperature, it may also drop leaves.

5. Nutrient deficiencies: A lack of nutrients such as nitrogen, phosphorus, and potassium can also cause leaf drop in Hoya plants. To solve this problem, fertilize the plant with a balanced fertilizer that is designed for indoor plants. Be sure to follow the instructions on the label for application rates.

In summary, Hoya plants can drop leaves for several reasons, including overwatering, underwatering, pests, environmental factors, and nutrient deficiencies. To solve this problem, it's important to identify the underlying cause and take appropriate action. This may include adjusting watering habits, providing more light or humidity, treating pests, or fertilizing the plant. With proper care, your Hoya plant can recover and continue to thrive.