Neither - give them as much light as possible, natural daylight is best - in a heated small frame if it goes subzero where you are if possible. OK that is maybe too expensive, but surely you can find them at least a windowsill (without curtains) if there are not many. They need light for continued healthy growth - their stomata will remain open and they continue to photosynthesise, ripening last year´s growth in preparation for next year. OK they will SURVIVE being put in a dark room - in the 17th century cacti became popular in Europe because they could SURVIVE a journey of several weeks bare root in a ship´s hold - but surviving is not the same as thriving - and we see you have already had a couple of episodes of etiolation - due to lack of light. My Mexican desert cacti go into cold frames for 3 months - Dec to Feb - this is the dry season in habitat - but I still get the odd flower in January, usually a Lophophora williamsii. In the shorter, colder days growth will slow to zilch but they still need light. As much light as possible but keep them dry. Good luck. Oh, and much sure all of your pots do have a drain hole.

I agree with Spanish Fly, that the more light you can give them, the better. However, I do understand that this isn't an easy thing to do.

Cacti are quite resilient, and if you don't want to use artificial lighting, you should keep them as dry as possible, with as much light as possible, and cooler temperatures (but not as cold as the ones you listed, 40-55 would be work).

Do you have a cooler room than the rest of your home? For example my back guest bedroom is always much cooler than the rest of the house. I'm worried if you keep this in a warm window and the environment is around 22C or 71F you will keep getting skinny cactus:(.

Plus I don't see any Epiphyllum. The two little guys in the blue mug could be Trichocereus. They should be in pots with holes. When growing succulents in containers with zero holes at the bottom it makes the processf growing them a little more tricky. So the drainage holes will make your life along with your cactuses life much easier;).

I do not see plant resembling Epiphyllum eiher. Kara probably gave you good ID.

How warm is your house? Is there a good window? Are the temps in C or F?

Of those 2 choices I would keep them in the attic, if you keep the plants dry they should survive an occasional overnight dip below 0 deg C.

If you get a spell of exceptionally cold weather you could always move them temporarily to the basement, you say you don't have many plants so not a major operation.

Nice to have the choice of 2 cold rooms to keep your plants in over the winter - wish I had that problem!

Yeah, you know. I don't have even one properly sunny spot in the garden (only lots of dappled shade), so to make things even Fate gave me two cold rooms...

I'll have to buy thermometer to put in the attic. It's pretty warm for now, but the weather over here likes to drastically change overnight.

Luckily, that's not many plants... it still is three flights of stairs from attic to the basement. I hope that the weather will be stable and I won't have to move the cacti too much.

Maria

You can get Max/Min thermometer for few dollars to check what the temps are like. Or you can spend more for one that will also sound alarm if temps drop below temps you set it for. But the money these cost, you could probably buy few lightbulbs. All you would need for few plants are 2 CFL lightbulbs that will cost less than $10. If you decide to buy them, make sure they are minimum 23W and 6500k.

I asked few questions you didn't answered: How warm is your house? Is there a good window? Are the temps in C or F?

These succulents have to spend winter indoors - you mentioned garden, but that doesn't help during winter...

I somehow saw only comment by Andrew... (it was a joke btw. no good spot in summer, but choice of two probably fine spots in the winter ;P )

To answer previous comments:

Yeah, there's etiolation from previous years, when I didn't overwinter them. They just stayed in the same spot all year round, same watering habits, etc. Our winters are very dark, it's usually cloudy for weeks and weeks. But we watered them so they tried to grow, and there you go. Especially the big guy, he grows fast.

Attic or the basement are my only choices of the colder rooms. All the other rooms are occupied and heated - I'd say 18-22, possibly higher since most of my family gets cold easily.

Temperatures are in Celsius btw.

I honestly have no idea what are their IDs (besides ferocactus). Those two small guys in blue mug are offsprings from the big bottle-neck.

And there are drainage holes in all the pots. In the mug too, I drilled it myself.

18-22*C it warm, and would be np for succulents to stay in as long as you get more light. You obviously understand that they can be kept 'sleeping' during winter in lower temps, but I would not go too low below 0*C. Basement sounds OK for this, but needs some light. Attic may be too cold if it keeps dropping below freezing. Your decision: personally, I would keep them in basement and get some lights. I have many succulents in windowless place in basement and use supplemental lighting.

Perhaps figure out cost of few lightbulbs and electricity vs 'inconvenience' taking them upstairs - downstairs (where they won't have light anyway).

I looked into it and those lightbulbs are damn expensive. With my salary I'd have to work for a week to afford one of them. Not to mention a set-up for those lightbulbs.

It's too expensive for a casual grower with 5 common cacti that put together didn't cost the half of the lightbulb.

I'll risk the attic. For now the winter is pretty mild...

Maria

Make decision best for you. I am not sure what lightbulbs you were looking for, but here is CFL for less than $3...

I bought 6packs for under $20 - and very often there are coupons available for energy saving products with $3 - $5 off. That would make it 6 for about 15...and they are good to use thruout the house. They use much less electricity than incandescent bulbs (23W comparing to 100W).

Well, those are much cheaper than what I found. Still, they are more expensive in Poland than in Canada, and I'd still need something to hook them up to. I can't really just set them up in the ceiling lamp and leave it on for hours, so I'd need to buy some kind of, dunno, desk lamp?

It would be nicer in LR to have some kind of lamp. I use them mostly in the basement, where 'looks' do not matter (to me) much. I made some 'holders' from plastic sockets, and pieces of wood. I also bought (previously used - so inexpensive) vanity strips that hold few lightbulbs each. That is why I suggested basement...Here are some pics - this set up will not win any décor prize, but it is in windowless basement and performs well. Home-made 'holder' in front, vanity strip (it cost me $5 and holds 5 bulbs) in back:

Yes, they can be in any lamp - desk lamp, floor lamp, ceiling fixture - but you need to have them directly above plants, otherwise you are just wasting time and money.

Do what you have to - but there are many solutions, including you bringing plants out of attic when it gets too cold. I have great attic space, with windows too, but without doing some work (and spending much more $$$) it is too cold for plants. And I have too many to bother bringing them up & down.

Btw, what kind of lightbulbs do you use throughout the house? Typical incandescent lightbulbs use much more electricity. I know Europe is very energy-wasting-conscious, and I would think most ppl use either CFL? or LED? lightbulbs. Am I wrong?

I have read that there are people that there are people that winter their cacti packed away in boxes, placed in the garage.

Well, I don't really care how the set up looks like. What I do care about are the costs/functionality of the whole thing. There's also always the question if the additional lights would really make a difference, or will the plants do just fine without it? I'll look some more into the possible set ups, maybe I'll figure out something that won't cost me month's salary. For now - the attic. I bought thermometer, so I'll be able to control temperature and in case it drops too low I'll move cacti to the basement... there's a possibility my brother will move out in January, so maybe then I'll be able to move the cacti into his room, as it won't be heated...

... maybe in Germany or France, but over here? Meh. My house has got few led lightbulbs here and there, rest is 'energy-saving' lightbulbs, which are pretty damn dark. But people still mostly use incandescent, as they're cheaper and brighter than energy saving, and have normal screws, while led lightbulbs mostly need different kind of socket... and I don't see many if any cfls being used.

Maria

You can overwinter all your succulents in cooler condition and very little or no water at all, but they need some light. Warmer they are kept, more light they need since they will keep growing. You know the results from your own experience.

I am bit surprised at description of bulbs available - but you have to deal with what is available.

We can get LED or CFL with different sockets. If you but one with high kelvins (I use 6500k/cool), the light temperature is very 'white'. And, as I said, they use only 23W comparing to incandescent that will be using 100W. So the cost of electricity is much, much lower. LED bulbs use even less (somewhere around 18W or so). These bulbs (CFL or LED) are more money to buy, but cost less to operate and last much, much longer.

I am not trying to lecture - just point out possibilities.

Maria - is ´doing just fine´ thriving or merely surviving? There is a difference - cacti do best with as much daylight as possible throughout the winter. Otherwise as much artificial light as you can manage. My guys go in a cold frame Dec to Feb - no water but loads of light - they are then well prepared for next season. Good luck with what you choose.

I'm not the one that buys lightbulbs in this house. We're kinda trying to switch to leds, but anytime a lightbulb dies, which is rarely, it's just 'get ma a new lightbulb asap' which means incandescent stack in the basement. Btw. how is the cfl's durability? Lower electricity cost wouldn't mean much if one had to buy 5 cfls in the span of time it would take for one incandescent to die.

I'd say doing fine is a sweet spot between thriving and surviving. Lets face it, most of them won't ever thrive in my conditions, with my short, cloudy, rainy summers and dappled shade of my garden, and while I might consider putting them under lights during winter, I'm not gonna do that all-year round.

I guess I'm just gonna have to experiment see what works the best for them and for me.

Btw. today it's 11*C in the attic compared to 2*C outside, which is a much higher difference than I expected.

I don't even have any incandescent lightbulbs in my house anymore - I use LED for most lights in the house (very few CFL), and many CFL and some LED for plants.

Just thinking here—-

What did you do last winter?

Would it be possible to keep some or all of the smaller ones in a location in the house, let the big ones be in the basement or attic?

Do you have any friends or family members who might be willing to take one or two to keep in a sunnier, warmer location? Plant sitting for the winter.

Rina, from what I saw in the stores CFLs are still quite pricey, as well as LEDs, but if their lifespan is really that much longer then maybe I shall start bothering my family about it.

Socks, last winter I had 3 cacti (well, "had" - they were in the house and mom took care of them) and didn't think much about anything plant-related. I just started learning how to take care of plants this year... so yeah, last winter I did nothing.

I don't really have that much, only 5 cacti, 2 of that small-ish.

Nah, everyone I know/family lives in small flats or houses without attic, basement being established as too dark.

Btw. temperatures in the attic over this week were stable 10-11*C, so I think even with outside temperature dropping, it should not go below 0*C.

On a side note, I'm plant sitting my sister's Tephrocactus articulatus inermis for at least 3 months, and I wonder if I should move it to the attic do Opuntioideae need to be overwintered?

Tephrocactus articulatus inermis is one I don't really worry about in my zone this cactus is fairly cold hardy;). Should be totally fine if kept dry up in your attic. They can be hardy down to -9C. I wouldn't let it go down that far, but even at 0C that guy should be totally fine;).

With LEDs one should be sure to check the color spectrum and lumens output. Most of the ones found at Lowes, HD, et cetera do not have the correct spectrum nor useful lumens output.

Was it Kara who had good success keeping cactus cool, dry and dark? I think that is the most cost effective way of dealing with it. No cost to set up, no hardware needed to buy as long as there is a spot in the house that remains consistently cold.

Do you want your cactus to thrive? Or more interested in just saving a few bucks?

Chris

Cool and dry works, bu they should have light.

Chris and Maria, I was worried that the basement and attic were going to get too cold during the coolest months, but if the attic stays around 10C-11C there should be no problems as long as everything is dry;). Even if the attic reaches 4C-5C everything should be ok.

Maria, I do think you should gets some lights eventually. I totally understand where you're coming from you don't have that many cactus, but it would make your life sooo much easier in the long run. In your zone it's pretty much impossible to grow nice looking healthy cactus without lighting assistance. In my zone I can get away with it. I'm even thinking about getting lights for next winter. I'm starting to accumulate more and more winter growers, special needs plants, and starting to grow more cactus from seed.

Plus you can start to grow more normal looking cactus;) and begin to really enjoy them.

Eventually I probably will :) Or maybe I'll move on to plants more suited to my zone.

What's the color spectrum and lumens output? Rina earlier said 6500k, that's the color spectrum, I think. What about lumens?

And thanks, I'm gonna make sure Tephrocactus is completely dry, and then move it upstairs with rest of the guys.

I agree, you can move on to other plants more suited to your climate. It's much more simple that way.