One in center is looking really bad and most likely 'goner', one on left is following it. You may be able to save one on right. Take it out ASAP as rot spreads easily. Your temps are not a problem, but most likely water retaining soil. Is there a drainage hole in that pot?

Plants on top are very different cacti than bottoms-rootstock. They are grafted since they most likely won't survive on their own, lacking chlorophyll.

Don't beat yourself up to bad these don't last too long. They're two cactuses grafted together. The top can't live without the bottom due to lack of chlorophyll. The bottom can last without the top though.

I would just throw away the two that are rotten. Unless you want to graft to another cactus, but wouldn't waste your time. These are easy to find.

The one that's still kickin needs the soil needs to be amended. Your mix looks very organic which is never good for succulents long term. So try to get your paws on some perlite or pumice. I'm assuming living in beautiful Vermont pumice will be hard to find. So perlite will do fine. A mixture of half rinsed strained perlite combined with half cactus mix.

When repotting get rid of all the old soil off the roots, and no water for a week after repotting. I would water as soon as the mix dries out. The bottom is a Hylocereus so these are more of a tropical type cactus. They can and like a little more moisture than other cactus that come from dry deserts. Don't confuse this with them wanting to be in a soggy mess. I don't mean this to offend, but the two above probably died from being in a soggy mess;). Think more along the lines of keeping them in a fast draining mix. Like the 50/50 mix I gave. So the roots can be washed with water a little more, but drains at the same time;). Along with good air circulation. Does that make sense?

Give as much light as possible. Goodluck;).

Thanks rina, Kara

I removed the two sick one and was able to transplant in leftover fresh cactus mix (although it’s not the perlite/pumice mix) which I will try to get ASAP. They were only $2.50 at Home Depot...I don’t know if these things are even real cactus? HD and Lowe’s also have a mushroom cactus in a pot that has some sort of a glued white gravel top, not sure what soil is underneath but I would hope that it might be a better mousetrap for beginners like me. Curious? Thanks again, Bill

Got it Paul and thanks! So, assuming I wanted to do some sort of assorted dish garden, I could do 3-4 in their own containers and set in a much larger container and possibly fill the whole thing with a proper mix making sure that I have good bottom drainage....? Thanks, Bill

Never got on well with these - red Gymnocalycium bred without chlorophyll - cannot photosynthesise - the stock does that for the plant. Always been short-lived for me, never found any that live that long . Basically a gimmick sold by nurseries that just want your money.

Thanks all, Last question....what’s a good starter Cactus that might have any secondary color or flower? Bill

Assorted dish garden - they may look good in photos, but not always easy to maintain. Especially for someone with little experience with succulent plants. Having different plants potted together could be more difficult to maintain correctly.

You have right idea: pot each plant separately in their own pot, then put pots in larger container. You can fill around with gravel, doesn't have to be a mix since each plant has their own. They should be in very well draining mix, and the container should have drainage hole. Problem will be when you need to water plants: unless large container has also drainage holes, water will just collect in it and get re-absorbed into individual pots. You need to either have drainage holes in decorative/large container, or take out each plant, water it, let it drain and set back.

You may want to start with same kind of plants, potting few of them into larger container, to have a 'fuller' look.

When growing succulents (cacti are also succulents), most important is to have great drainage. That means in a mix and the container. Next would be lots of light and good air circulation.

I have two of these and I've been able to keep them alive a couple years. The root stock is tropical but easy to over water so I give a fin of the root stock (there's probably a better word than 'fin' but that's all I can think of right now) a gentle squeeze. If it feels thick and firm then I don't water it. If it feels a bit thin and has some give then I give it some water. I keep the two plants in a south facing window that gets full sun during Winter and shade during Summer but I'm not sure how important that is.

Mammillaria bombycina is a pretty cactus, attractive hooked spines, ring or two of pink flowers at a young age. Easily cared for.