my two succulents are sick and I don't know what to do. My tall cactus has turned black at the base and is dying (stems are turning black and falling off). Can I cut off the top and replant it or is it done? Also my small succulent (unsure of the name has a strange discoloration that forms on the leaves and now they are all falling off). Does anyone know what the problem is and or if this is a disease? Thanks for your help
Your little succulent is a variegated jade (Crassula ovata). Maybe someone else can help you with your questions about their sickliness.
I'm afraid one of your cactus has rot, I've personally have never been able to save them after that started, but the others seem OK. Pull out the rotten one and only water once every month or two in the winter. Cactus shrink and expand with how water they have been getting and they look fat, wait till they get thinner before watering. The Jade plant doesn't grow much in the winter around here so let it dry out well too, maybe watering it every 2-4 weeks depending on how dry the air is. In the summer you should let it dry out between waterings but you can water it much more, maybe once a week or so if it is getting enough sun. I see it is exceeding salt crystals on the leaves, that's the white spots, so don't give it any fertilizer. I don't think I would feed it at all this summer, and maybe only 3-4 times during the summer after that.
You may be able to save the rotting cactus. Remove it from the soil, cut off the rotted section, and leave the remainder to dry. Once the cut end has callused apply some rooting hormone powder to it and plant in soil. It's worth a try. I think the hormone powder is optional due to the nature of cacti. The important thing is to make sure the cut has dried thoroughly before planting.
