The plant commonly known as a Christmas cactus is known for its succulent leaves and colorful blooms. However, the Christmas cactus is not the same kind of cactus that grows in the desert, but is a member of the Zygo-cactus family, which live in the humid rain forests of Central and South America.
Christmas cacti need two months of at least 13 hours of uninterrupted darkness per day to bloom, and are sensitive to both over-watering and under-watering. Water a Christmas cactus when the top inch of soil in the pot feels dry to the touch.
Find a clean flower pot, or wash a flower pot with soapy water that is two inches larger in diameter than the pot where the plant is currently planted. A clean flower pot will help control any plant diseases that may have existed in the previous pot where the Christmas cactus was located. Using a pot no more than two inches larger than the previous pot prevents the plant from sitting in a large area of wet soil that can rot or sour. When the potting soil begins to rot, the organisms that cause the soil to decay consume available nitrogen in the potting mix.
Repot the Christmas cactus in a potting soil high in organic matter, such as potting soil listed for African violets. Plant the Christmas cactus at the same level or slightly higher than it was previously planted.
Carefully remove dead leaves or plant sections by pinching at the leaf joint. Using scissors to make multiple cuts can spread disease throughout the plant. Remove shriveled plant sections and sections that are soft and white.
Water the Christmas cactus with a balanced fertilizer listed as 10-10-10 to settle the soil. Apply the fertilizer as directed and do not overfertilize. Allow the top inch of the soil to dry out before rewatering. In their native habitat, Christmas cacti live in very well-drained soil or organic matter that dries out at certain times of the year. If providing darkness to force a bloom period, do not fertilize during the two months you are providing artificial darkness for 13 hours per day (that articial darkness is necessary for the plant to thrive).
Put the plant in a bright area with higher humidity than the previous location with a constant temperature above 65 degrees. If you set the plant in the bathroom, be sure there is a constant source of bright light to reinvigorate the plant. If you cannot provide a higher humidity than the previous location, use a plant mister to spray the plant with a fine mist of water every few days.