Cut it now, can't wait until Spring, do as shrubs n bulbs advises, let it dry, add coarse sand or gravel to the damp cactus mix, bring it into the house and wait until you see new growth, then water with warm water. After it has produced a few more leaves then transplant it into regular cactus mix, you must do everything you can so it won't rot out before it gets those first few new leaves. Don't water it again until spring. Remember the hylocerus is a jungle tree dwelling plant (and clifs along the coast usually from Brazil with 3-4 angled stems. It needs a warm winter home. I hope I gave you enough information help you. Norma

Thanks for the pic. It does look like peat. Watering 1x/week is probably too much. Peat retains water; it will be dry looking on surface but still wet inside. On top of that, you have it in cache pot that doesn't allow for any air circulation and if there is too much water, it will sit at the bottom and be re-absorbed back. And covering surface with plastic doesn't help either. I hope this doesn't sound mean - I am just pointing out things that contribute to plant rotting. If you want to grow succulents successfully, it would be good idea to learn about well draining mix - adding generous amounts of perlite, grit, turface, scoria, pumice - any of these (best would be more than 1 ingredients) will give plants drainage and air circulation. If you use that kind of potting medium, plastic decorations may be ok - but just few. Cache pots are much nicer than plastic - so I don't blame you for using it. Just make sure that after watering (wait about 30 min) you take the plastic pot out and drain any water that may have accumulated in outer pot. It may be easier just to take pot out, water it, let it sit on a saucer and after a while put it back into cache pot. I think that your plastic pot sits too low in outer pot, and also plant is potted too deep - raise soil level when re-potting, and raise the pot too. Btw, what happened to the top cacti? (the colored one) Rina

If there is any healthy rootstock, then yes. But the way you described it is little confusing: you say that it needs to be cut above rotting - which one is rotting, stock or gymno? (the Moon cacti = gymnocalycium mihanovichii). If rootstock, it will have no roots. It will eventually root and maybe fast, but I don't know how much that would influence the gymno (you would have 2 plants without roots for a while). This grafted cacti are typically short lived; the rootstock usually outgrows the gymno very fast. It is a good idea to post a photo - easier to see what the plants are like.

I posted in here a little while ago with my moon cactus top that i had placed in a pot of soil and it was growing roots. Only the darker purple will do this. As it has just been an experiment for me so far I simply chopped it off when the base of the cactus got rot and placed it on a pot of soil. (Yes I am aware its not the ideal soil for succulents its probably about time I changed it over) Its been sitting on that soil now for almost 6 months and has grown a healthy amount of roots. I gently disturbed him so you guys could get a look at the roots so you could see for yourself, didnt want to disturb too much though so hopefully you get the gist.