A well-draining, sandy soil is best for succulent plants. Powdery mildew, fungus, and root rot may occur if your plant has been overwatered or planted in a pot without drainage holes or in soil that is too dense. You can still plant the cutting if you don't allow it to develop callus. You must sterilize the cutting to avoid spreading diseases or harmful substances. Root rot is the most common disease and it is mainly caused by overwatering. To prevent root rot, you can add gravel layers above and below your potting mixture.