I have a 100 year old cutting of a Christmas cactus. I was told to just put it in water and it will root. It has been in water at least 3 weeks now and nothing is happening.
These plants are typically propagated using soil. Don't try to root your cuttings in water - they'll turn into a slimy mess and chances are you'll just be wasting your time.
This article will help: https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/how-to-propagate-and-plant-christmas-cactus.htm
I have a large Christmas Cactus that is beginning to get wilted 'branches' but only on the ends. Is it time to repot the plant or could it be that it's becoming too dry between waterings? How will I know when it is time to repot?
Can you give me tips on repotting the Christmas Cactus?
You want to put it in a pot that is at least 2" wider and 2" deeper than the root ball (container size) currently is. Repot and care for it as you normally would. These articles should help: https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/advice-for-christmas-cactus-care.htm
https://www.gardeningknowhow.com/houseplants/hpgen/learn-more-about-repotting-houseplants.htm
How do you take care of the cactus after it blooms, and how do you get it to rebloom?
The following articles should be of some help to you: https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/how-to-make-a-christmas-cactus-bloom.htm
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/advice-for-christmas-cactus-care.htm
My Christmas cacti has lost a lot of its limbs. Is there a way to save the lost limbs? Can I put them in water and will it develop a root? I live in a very hot climate in AZ. I only have a swamp cooler and I have it in the shade by insulated curtins. Is there any hope for this cactus to return its lost limbs before the next Christmas blooming?
Christmas cacti are easy to re root, just put the lost limbs in some water, place in diffused sunlight. You can pot them in a good quality cacti soil once they root. Your mother plant should do just fine. Give it a light feeding of fertilizer to help it grow more brachs. They are one of my favorites as a house plant.
I planted a Christmas Cactus a few months ago and it was doing great! It was having new growth. Then it got thin and limp looking. I have been watering it more lately and actually water with Miracle Grow. Before that I probably only watered once every 2-3 weeks, but read to water more often. Would you have any ideas?
It does sound like you may have overwatered and it has developed root rot. They should only be watered when their soil has dried out. This article will help with root rot:
https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm
Stop watering so often. Cactus and it's euphorbia and epiphyllum cousins prefer minimal water. It's best to only fertilize once a month in summer, not at all in winter. Also, to encourage flowering for late December, don't water it at all from October on then only minimal water when the soil is dry. Too much water will cause the buds to fall off. The best rule of thumb for a Christmas cactus (or any other cactus and it's cousins) is to water it once a month, and never let the pot sit in water.
How big a pot should you have? What kind of soil? The cactus is older and fairly good sized but looks like it needs to be replanted.
When you repot, it is best to move up to a pot that is at least 2 inches larger than the last pot. For the Christmas cactus, use a cactus soil mix or mix vermiculite and normal potting soil in a 1:2 ratio.