Rehmannia is a genus of plants requiring moderate to high light, regular watering, and prefer acidic, well-draining soil in a warm climate. Care must include vigilant monitoring for pests like aphids, and prevention of diseases such as root rot. Seasonal changes in light and temperature require adjusting the watering schedule and potential relocation. In winter, indoor care is often necessary due to rehmannia's sensitivity to cold. Overall, while rehmannia requires close attention, its needs are generally manageable, given the right conditions.