Indoor citrus trees are very temperamental to change, and don't like to be left without nutrients. this episode will cover the 3 reasons your lemons, limes, oranges, and grapefruit are dropping. Many indoor houseplants are tropical species, and when they are grown in the dry indoor conditions found in northern winter climates, they will react by dropping leaves. this is a natural response since the plant is attempting to conserve its moisture loss by reducing the number of leaves that are transpiring moisture.. �