Q.christmas cactus
I have two Christmas cactuses that are very old and the stems have gotten woody, how do I care for them?

If the plant is larger than you desire, you have 3 options. Pruning back the tips may encourage leaves to break from the woody areas; dividing the plant; and taking cuttings to start a new plant. I've seen holiday cactus respond well to all three. The plant probably has some large and thick roots. If you divide it, cut back the largest roots so they will fit in the new, smaller pot. Trim away dead roots. This plant likes to be snug, not crowded, in its container.