I have a Christmas cactus that my mother watered to much while I was away for several months, anyway, I have transplanted to new soil, and still after several months it looks limp and the leaves look dried out. Help please?
Root rot is not caused by a disease in the soil so replacing the soil does not help. In fact, it may further damage any remaining healthy roots. The only remedy for over watering and rotting roots is to allow the soil to dry out sufficiently for air and oxygen to penetrate back into the root zone. However, if most of the roots have already died from rot, then nothing will bring them back.
When roots die, the plant cannot absorb water so the plant looks limp and wilted, as though it was not getting enough water.
Background: Roots require both water and oxygen. When soil is saturated from watering, then the water displaces all of the air in the tiny pockets scattered throughout the soil mix. As soil is allowed to dry out, air comes back into those pockets. Both water and oxygen are critical for a plant’s survival. Soil that is kept too wet for a long time deprives the roots of essential oxygen causing what we call root rot. All plants need to dry out regularly just as much as they need to be watered regularly.The only solution for over-watering and root rot is allowing the soil to dry out properly.
Replacing soil usually removes the tiny root harbors that do most of the work, thereby aggravating the problem
If your Holiday Cactus has not revived after several months, then the chances are it will not. Make sure the soil is drying out properly, be patient and maybe new roots will begin to grow and save your plant, but keep your expectations low.