I had a fairly castle cactus that had the same issues, and ultimately got rid of it before it spread to my other plants.

The middle cactus is most likely a goner, but you can cut it above the rotten part, making sure the only thing left is healthy and green, let it callus over for a day or two, and then try to root it (search this forum for tips on rooting cacti). I'm not sure it will make it.

The cactus on the left is probably salvageable, but you've got to get it out of that pot, and into a pot with a hole. Terracotta would be best, and choose the size that's no more than an inch larger than the plant itself. Choose a rocky soil, not crummy, water-retentive Miracle Gro crap. Don't water much. It should be okay.

Also cactus like direct sun. When plants don't get the amount of light they need, they survive, but they grow strangely and will start to look weird and skinny. Just a heads-up on that eventuality if you're going to keep it in indirect sunlight.

I see 4 different plants there - Haworthia in the back.

They all need container with drainage. Well-draining potting medium. Watering when medium dries out. Lots of light - not indirect sunlight.

If you are serious about saving these, you have to act fast. The yellow grafted cactus in front may already be a goner, but you may be able to save it if you cut off the lower brownish part, which appears to be rotted. Cut up until you only see green tissue. You will have to let it sit for a week before trying to root it.

All the plants need to come out of that pot. You cannot grow plants in a pot with no drainage and hope for success. They all need to be planted separately in pots, preferably clay, with a free draining soil. Never water on a schedule. Cacti can go all winter with no water. Your Haworthia, it appears, in right rear, might need a little more water than the cacti. Just as importantly, these all need brighter light than you are providing, if you want them to thrive. So your office setting is really not the best place for them.

Christopher

Thanks for everyone's help. I realize my questions were very basic and probably boring for most folks here. And I didn't realize that my moon cactus was somewhat frowned upon until I read in some of the other threads. Also, I didn't even know that people paint some plants, but I saw some at the store, two nights ago and chuckled, as I remembered some of the threads here.

I went ahead and re-potted 3 of the plants, each in its own clay pot that has drainage. The moon cactus I was able to slice above the rot and it looked healthy. I am waiting for that to callous over, in the hopes that I can try to root it and prolong its life as long as I can. I am keeping my fingers crossed. I will let folks know if it makes it through this.

One question that I do have is whether I should add any water to the newly potted plants. Over-watering and poor soil and bad drainage caused my previous problems, so I was gun-shy about adding any water, just now, but I thought I would see what others think?

NO WATER.

And no matter what we think about the moon cactus (but since you're asking, I think they should all be gulag'd), if you like it, that's all that matters. Obviously there's a market for them, and they're many steps shy of painted succulents, so there's that.

You should gradually increase the amount of sunlight. I understand wanting them on your desk at work but indirect sunlight isn't enough. To increase the light I often use a screened south facing window (north facing if you're in the southern hemisphere) and position the plant in various places near the window to increase the light it gets. For example, placing the plant next to the left or right of the window will give the plant half a day of direct sunlight or less. At the center of the window the plant will get more than half a day of direct light. Later the screen can be removed for more light if you want to try giving them more.

The cactus on the right of your picture probably needs the most sunlight of all the plants in the pot. The Fairy Castles and grafted Gymno. might sunburn the easiest in my experience with the plants you have.

You're disappointed that you messed up but the odds weren't in your favor. Some things were working against you: no-drainage bowl, different plants in the same pot, and a couple plants that can have some problems. I almost never put a decorative cover on the soil. That makes checking the soil more difficult. There are some issues and you're learning about them. Disappointing to me is when people serially buy plants and toss them out if the plants have the slightest problem.

You thought the painted plants were funny. Did you see the artificially colored real straw flowers that are glued to the plants?

These appear to be in conditions lesd than ideal for C&S. 1 theyre in an office and cacti need bright light. 2 theyre in a deep bowl, I would check there is drainage for any water that is given. That brown patch on the grafted Gymnocalycium looks to be a sign of overwatering/poor drainage. I would remove them from the bowl, spread them out on newspaper and have a look at the roots, removing any black, rotten roots. Then leave to dry for a day or two-dont worry, they can survive long periods of no water because they are succulent. Then repot each into its own pot in well draining peat-free soil, in a bright spot. But if they have been in this situation for a while then they will need to be acclimatised to the new brighter spot in order to avoid scorching. A bright area with no direct sunlight would be OK to start with.

The moon cactus did not survive the slicing/rooting.

So now I have 3 of the 4 cacti, in clay pots, sitting in a south-facing window. 2 of them seem to be ok, the other one I am not sure about (see picture below). What is that cactus called? The branches (not sure if that is the right term) seem weak and drooping, some look discolored, and some have a really fuzzy look about them. Are they goners? What am I doing wrong? I am losing confidence that whatever I touch seems to die. Do I need to attend a Cactus for Dummies workshop? Any recommendations.

I believe it is Cereus tetragonus ?

Regardless what cacti it is, it needs to be in well draining mix as mentioned in few posts above. Looking at the photo, your mix looks too dark - I would guess it has lots of small particulates (like a soil or peat) and stays wet for too long. Just a guess. The plant should grow upright and should be green. Some 'twisting'/spiraling of branches is expected (not sure, but I think more as plant ages).

The plant looks like it has mealy bugs or scale in the circled area.

When we re-potted this plant, about a month ago, we used "Miracle Gro: Cactus, Palm and Citrus Potting Mix", which advertised itself as a fast-draining formula. I did not add any water at that time or since then. The person at the garden shop recommended this soil. Do you feel that is a bad soil for this plant?

Mealy bugs, scales? Maybe I need to get out of the plant business before I kill anything else.

I am amazed by all the folks here who are so good at this stuff and know what they are doing.

David

You just have to stick to it, don't give up and read and try to remember as much advice you get here :)

Sadly, bagged mixes, more often than not, do not deliver what they advertise. If you look up list of ingredients (should be on every bag), you'll find what it contains - often peat, sand and these tend to be very fine and probably large % of the mix. Finer the particulates get, drainage gets worse - they 'stick' together and hold water too long. Drainage is impaired and the roots get damaged with too much moisture, and can't breathe either. There is probably some perlite added, but probably small amount. It is best if the ingredients of the mix are of similar size. That is why many of us mix our own.

Ok, so the 3 plants that I have are: (see pictured)

It sounds like the drainage still isn't good, after the re-potting? A few questions:

1. can the middle one be saved, or is it simply a goner? One of the replies, above, indicated they thought it may have mealy bugs and/or scales. Do you think there is anything that I can do? I don't want to give up on it, if there is hope, nor do I want to hold out false hope for it.

2. is there any reason why I can't re-pot these, again, this weekend? I last potted them 1 month ago and I wasn't sure if all this activity would harm them. I should have done it right the first time.

3. If I take the cactus soil from the store, mixing it with sand and pebbles, would that be suitable? I was looking on a site and they had the statement about making cactus soil: "In most other areas and in the home interior, the plants are fine with one part washed sand, one part soil and one part gritty amendment such as pebbles or even pot shards." Do you agree with this approach or what would you recommend?

Thanks for everyone's help.

David

"NO" to ..."mixing one part washed sand, one part soil and one part gritty amendment such as pebbles or even pot shards"... In my opinion, that is a bad advice :(

Well-draining mix consists of few ingredients that are of approx. of same size. Mixing small and large (pot shards=large) defeats the purpose: to have mix that allows drainage and aeration. Small particulates sooner or later fall between large ones, and clog up any space. If one puts out effort to make a mix, it should be the right one.

I would at least buy a kitchen sieve (from a dollar store), and sift out the cactus mix you already purchased. Keep what stays in the sieve - larger particles. Buy a bag of perlite, sift it to get rid of dust, and mix minimum 50/50 with the sifted soil. I would consider doing this if you don't want to spend time and little $ to make better mix, many refer to as gritty mix or 1.1.1 (proportion of ingredients). If you search this site for it, there is hundreds threads about it. There are also many versions of it - and depending on growing conditions, it could be adjusted.

If you can find grit, pumice, turface, scoria - any of these would be great gritty amendment. I would recommend not using sand (not sure what is referred to as 'washed sand' - it may be grittier), unless it is grainy - sifted thru the sieve, using only what remains in it - sand sold as horticultural sand may be OK.

Unless you improve the mix to improve drainage and aeration, there is no point in re-potting - JMHO.

Tried re-potting the plants, yesterday, with better soil, as mentioned, above. My question is this - do the plants need any water at this time and how do I know when they need to be watered? (My mother-in-law told me to add some water today, but I haven't done that. I wanted to check on here first, as well as do some investigating online.) When I re-potted the plants yesterday, upon removing them from the first container, the dirt was bone-dry and caked hard like a brick.

Cacti and succulents can go a LONG time without water. Wait at least a few more days to let any root damage callous over. With these types of plants, it's always better to wait. I give my repotted plants 3-5 days.

..."The dirt was bone-dry and caked hard like a brick."... that's what peat does, it is hydrophobic and once dry like that, it is very difficult to re-wet. Did you get it off the roots?

If it was over-watered, you could wait bit longer.

As RINA said above, removed that old, dry, caked media is very important

C&S repotting job takes least a fortnight here... Day 1 - unpot & clean off roots. Leave in cardboard tray under eaves for least a week.

Then pot into undampened mix and replace under eaves where they get some light but no direct rain.

Dont water till some sign of growth is detected; unless it's a baking hot day and plant is screaming for water.