A Christmas cactus is an ornamental plant that does not require much care. However, it does need regular watering and fertilization to ensure it remains healthy. The best fertilizer for a Christmas cactus is a balanced, slow-release fertilizer that contains a mix of nitrogen, phosphorus, and potassium. Apply the fertilizer once a month during the growing season and once every three months during the winter. Additionally, it's important to keep the soil moist but not soggy and to provide bright, indirect sunlight.