Leaf drop can happen if the plant is allowed to become extremely dry. Mealybugs are the most common insect pest of jade plants. They look like white puffs of cotton. Wipe them off with alcohol using a cotton swab. Do not use insecticidal soap, since it may damage jade plants.
Spider mites can cause plants to lose their green color and appear dusty or speckled.
Jade plants do best where they get four or more hours a day of direct sunlight. Plants grown in sun can withstand higher temperatures than those grown in poor light. During the winter months, protect plants from drafts and do not let their foliage touch windowpanes. Soil should be kept moist but not wet while plants are actively growing in spring and summer. During the winter, let the soil dry between waterings .