The shedding of flowers and immature fruit is typical for citrus, which tend to produce more flowers than can be supported by the leaves. To achieve a balance between the supply and demand for carbohydrates and other nutrients, flowers and fruits are shed during and shortly after bloom, which often continues until harvest. The amount of fruit produced by citrus is proportional to the size of the tree, and the size of the container limits tree size. However, you can still improve your harvest yields by providing optimum growing conditions. To achieve these conditions, place your Ponderosa in a room receiving bright, direct sunlight, and water it regularly during the growing season.
Adequate moisture is especially important, since water stress can speed flower and fruit drop.
Water your citrus when the surface of the medium feels dry, adding enough so the excess drains out of the bottom. Water less often during the winter months when the tree is resting. A minimum winter night temperature of 40 to 50 degrees F with an increase of 5 to 15 degrees during the day is ideal.