Your plants are suffering from lack of light (maybe even water - but I can't tell what 'soil' they are in). It is very visible in plant #1 - almost white, and skinny growth = etiolation. That is too warm to keep them without water, and they should not be in complete dark. 18-20*C is warm, they will keep growing. In either case, there should be good light available - cold or warm. In your conditions, give them lots of light, water as they need and they will continue growing.

Thank you I will get it out of the closet and put it in more light available location. We'll I wanted to overwinter them. But it since they water the cactus before I bought them and they won't go dormant because of that... So I am stuck, I can't do a dormancy period and I can't provide enough light.

As I said, they still need some light, even during dormancy. If you think of succulents in their habitat - they have always regular days and nights. Winter days are shorter and there is less sunlight, but there is always daylight. So dormancy doesn't mean pitch dark.

And since you watered them - that would not be a problem either because sooner or later potting mix will dry up - so they still can have many months of dryness. Your "problem" is warm temps. So if you don't have cool space, just 'roll with it'. You can provide extra light - many of us do, by using supplemental lighting.

I do not know what is possible and easier for you - but there is solution available...Btw, I don't think you mentioned your general location and/or growing zone - that info would help to give better advice. If you look thru some posts, you'll find out that mos ppl put that info next to their names - so we don't have to keep asking :)

Great, you are right, I am from Paris, Zone 7.i just edited. I cannot provide lighting until Christmas time, and you are right It is really too warm inside, and too humid in my bathroom. I have a terrace though, maybe I could use some bubble wrap around a shelf outside

Thank you for providing info about your location :)

Not sure about bubble wrap, it may be, eventually, too cold for succulents. here are over 300 sp of mammilaria - and many come from Mexico, and most of those will not like cold. You should find out what yours is and look for info on its hardiness. Same with rebutia - IIRC, they will survive in temps just touch under 0*C, but freeze otherwise. Find out - I have only 1 and it spends winter indoors.

So using bubble wrap may help to 'extend the season' but I don't think it will be enough for whole winter. Check minimum winter temps in your location - I think they are less than -10*C (?) - I believe that is too cold.

You can get some supplemental lights and do not need too many if you have just few plants. Few CFL (or LED) bulbs in floor lamp or hanging fixture may be enough.

When going dormant it's best to do it slowly. Stop watering a month in advance so when the cold comes the mix will be dry. For dormancy to happen the temps need to be about 7C;).

I know Rebutias can handle some chilly weather around -7C. Do you know what species your Mammillaria is?

That little set up may work you just have to watch the weather forecast. If you can keep them dry, cactus can handle it a little cooler, but a bone dry mix is a must. You could double wrap it and put a thermometer in there and see how warm it keeps. I have a digital one where I can read the temp while inside my house.

The problem people run into when not letting certain cactus go dormant is they don't get blooms. I know Echinopsis and Rebutias need that dormancy to get tons of flowers.

Your Rebutia looks so funny;). If you can get your cactus dry and that little shelving unit to stay around 7C they will be fine;). Goodluck:).

Thanks I think I can put them outside in the diy greenhouse thingy during the day of tolerable temperature and put them back inside the house during the night and wait to get a led light in Christmas. I am not sure when they watered them for the last time

Peter

I hope you are not suggesting that ..."Such a load of erroneous BS is spouted about this topic"... on this forum. I believe most (if not all) suggestions is to make sure they get light regardless time of year.

Huh, funny how people read the same thing, but hear different messages. I've been following this thread and I just went back and re-read it. Not one person, other than the OP who realized their mistake, was saying to keep the plants dark for the winter. Rina and Kara repeatedly said to give it light, just cooler temps and dry....

Yeah "overwintering" "or water after dormancy" sticky or cactus care months by months would be cool.

I wanted to wait till I had some time to respond to the BS comment made by Peter. The fact that he thinks keeping cactus dry, dark, and cold is BS is his opinion, but you know what they say what opinions are like;).

The first comment Rina made stated Kami's error. It was too warm in her apartment. Kami says she's a beginner, which we all were at one time, and she probably got some info and was confused. Totally easy to do there's a lot of info out there, which makes it easy to get discombobulated;). Maybe to her 18C is chilly for an apartment temp. In the cooler months I would consider 18C to be chilly for my home, but wayyy to warm to get your cactus to go dormant;).

There are many cactus growers that send their cactus into dormancy in late fall and winter. Including myself. My Echinopsis, Rebutia, Astrophytums, Echinocactus, Parodia, and SOME of my Mammillaria and Gymnos go dry, dark, and cold. I'm sure I'm missing some too;).

These cactus are put on shelving units with either blue tarp or thick black trash bags covering them. Right now I'm using my blue tarp for something else, so I cut up two thick black trash bags from Home Depot and put them over my shelving units my potted cactus are on. They have been under there for exactly two weeks. I uncovered them yesterday for the first time in two weeks because the next few days will be low/mid70F's and nights around mid 50F's. Too warm so I uncovered, and no etiolated cactus. I know gasp;)! They have been in almost pitch black for two weeks and there are zero signs of etiolation;) because the temps have been cool enough. I'm also proud of myself because all the cactus were completely bone dry. I was expecting a little dampness on some, but nope. Way to go me;).

My other cactus that may be a little more sensitive or won't fit on my shelves outside I keep on a wooden bench in my dark cold north facing garage. I know dark and north facing is a little redundant. They're in front of a window, but the garage is very dark. So if any cactus that is not dormant by now would start showing signs of etiolation. I checked on them yesterday, and everything is uneventful. Zero etiolated plants. Normally I check on them a couple times a month. Usually looking for pests.

I have a handful of cactus that have been sitting in a couple plastic containers in my garage because they had meallies. So they need to be away from everything else. They get almost zero light. I mean they're sitting in a couple plastic containers on the concrete floor up against a wall in my cool garage. These cactus have been in cool enough temps, kept dry, and in the dark for 3 weeks.

Not everybody is lucky enough to live in "Sunny Spain" so overtime people had to figure out ways to keep their cactus when it started getting chilly. I think the whole keeping them dark was from people trying to keep them cold and dry. Like in garages, attics, and basements. There's a member on here that lives in the Netherlands, and I remember him saying his neighbor keeps his cactus in a barn during the winter. I can't imagine a barn in the Netherlands during the winter has all that much light coming through;).

Another thing how can you compare a desert cactus growing in their natural habitat to growing that same cactus at somebody's home half way across the world. Of course they don't go fully dormant in their natural habitat. It's their ideal, but somebody's apartment in a hardiness zone 7 is not. It's like comparing apples to oranges. Cactus will go dormant in their natural habitat if it's too cold or hot.

I'm actually thrilled that somebody figured this way of growing out! For 8-12 weeks I can put a good majority of my cactus away and allow them to go dormant. I don't have to worry about them rotting. Last year I lost a couple of Mammillaria I really liked. Nothing rare, but they were special and beautiful. I lost them to rot because of all the rain we received last winter. Didn't protect them good enough. If I would have kept them in my cool, dry, dark garage I would without a doubt still have those Mamms.

Now I must make it clear there are cactus I would never treat like this during the winter. For example more tropical cactus from places like Brazil could not handle this type of treatment. I would never treat grafted cactus this way either.

Every winter a good majority of my potted cactus get treated like this, and I have never ever had an etiolated cactus. Never;).

The whole surviving not thriving thing is off base too. If you get the whole cactus dormancy thing down they thrive when out of dormancy.

So Peter just because it's not the way you grow your plants doesn't mean it's BS or inferior. There are many that choose to grow this way or their climate doesn't allow them to keep their plants out all year long. If only we could all live in "Sunny Spain";).

Kami, I'm pretty sure you know where you went wrong, and we've all made mistakes. For dormancy to work the cactus mix needs to be bone dry, temps around 7C, and if you have those two things than yes you can keep them in low light, but the mistakes you make now is how you learn. The best advice I can give you is to know your plants. You don't need to know everything about them, but the cliffnotes will do;). It paints a picture for you. I wish I had known that in the beginning so I wouldn't have killed plants out of ignorance. Goodluck to you;).

Peter Dennis, you seem very knowledgable and respected here. As all plants growers/lovers I reckon we are all trying to provide the best cultural conditions to our plants. I found really different information here when i searched. From someone putting them in the fridge, to someone wrapping them with roots naked in news papers. I wanted to induce dormancy to have flowers maybe next year, but i am new to cactus, therefore i failed. I take it upon myself. What i find difficult is to find the right information. i found a french forum with montly care for cactii and succulents, in the next two weeks i will be translating it and maybe you could provide information here, correct and give your feedback in a cheerful way :). We don't all have lights and when purchasing or getting an interest in cactii maybe this information should be out there as for tropical plants high humidity is a requierement.
With kindness and an open mind, with my best english.

There is a disconnect in the discourse here that is actually pretty easy to fix.

First, of course commercial nurseries want to keep their plants active and growing all season. So they will bend over backwards to make it happen or they'll miss their shipping targets. Peter is also correct in that photosynthesis does not stop just because it is cold. In habitat, these plants keep to their specific schedules, doing plant-y things adapted to the seasons. There are cacti that do go dormant in winter (I have one growing outside in the yard, looking icky right now), so there is that.

But, in my basement as a hobbyist who does not have a shipping schedule to meet and because I am lazy but do not want to ruin the few cactus I have on my bench, I keep them bone dry and cold like Kara does, carefully inserted in the periphery of my winter lighting setup. I force them into the lowest possible level of activity because I want them out of my hair in winter.

So, Kami, relax. While it is true that there is no fixing the etiolation in those cacti you have, you can stop it getting worse. If your outdoor does not go below 5C, you can safely keep them outside provided they are brightly lit, well ventilated and they never ever get wet.

There is one plant you can keep in the closet, though---Zamioculcas zamifolia. For a year. With no water. lol You may lose a couple of stalks but generous watering and an apology will bring the rest back.

Peter, your comments are wayyyy to easy to counter. Plus I've read a couple of other comments made by you, and I feel like I may be dealing with a little bit of a troll here. It's not just putting them in the dark. You're cherry picking my comment.

I said what I needed to say.

Yay, Pagan is back;)! Always has great knowledge and thoughts to share. Missed your creepy little avatar;).

True lack of sunlight from your closet keep on the dry side in your aprt and water when u needed to very little they go dormant in the winter time and no fertilizing

Here is something that i found on french cacti forums, i translated what i could with the help of an online translator.