My first reaction would be overwatering: yellowing of many leaves, soft leaves and easily falling off - the plant is likely water-logged.

What kind of 'soil' is I potted in? Is there a drainage hole in the container?

If stems are growing long & skinny, the color is kind of too light, it is lacking sufficient light IMO. Succulents need very well draining potting mix that should almost completely dry out between watering, and lots of good light.

Btw, it would be helpful if you add your general location or at least a growing zone next to your name (I realize that you said 'pretty cold' - but how cold is 'pretty cold?')

Thanks,

It is probably potted in some pre-packaged cacti soil. There is one bigger hole at the bottom of the ceramic container. Northern central Europe, according to the Internet that's 6b hardiness zone (like Charleston or Pittsburgh - right now the temperatures are 32 F (0 C), daylight lasts 8hrs and there is almost no sun since over a month.

The plant is in the flat's sunniest spot... Should I use artificial lighting on it?

Shall I repot it into other kind of soil (half soil, half gravel?) and if so - how - if the plant is so brittle? Do you have any suggestions? :)

Katarzyna

I am in zone with similar conditions. I have lights for all my succulents, otherwise they would get really etiolated.

The mix many of us use for succulents id made of grit, perlite, pumice, turface, scoria - whatever materials are available to you. I use grit and perlite in equal portions and small amount (10-25%) of turface. I can't get pumice or I would use that. Many ppl use ready-made cactus & succulent mix and add lots of sifted perlite (50% or more) to it to increase drainage, it seems to be working well for them (I do not have personal experience with that mix).

If my plant, I would take it out of the soil to see how roots are doing. If they were in wet soil for a while, they could be damaged. But plants could be re-rooted, as long as they are no thoroughly rotten.

After getting rid of all the soil from the rootball, I would let it air dry on something absorbent (to get rid of excess moisture). Then I would pot it up into quite inorganic mix - if you have only soil and grit, can you get bag of perlite? I would keep soil to no more than about 20% of total mix (if using any). These plants grow in habitat in rocky quartz fields and on steep, shady quartzitic sandstone cliffs where they have excellent drainage provided by very porous soil - so try to get closer to that king of mix. They are, IIRC, summer dormant, so should grow now but would likely need some more light. In low light it gets etiolated, weak, and looses green color. Leaves turn yellowish but should not be squishy. The plant has plump leaves, so it could be harder to judge for water-logging, but if leaves are falling off easily, I believe it is too wet. Some leaves and branches that will fall of while handling carefully would probably fall off anyway. Putting plant in better drainage and better light should give it a 'boost'.

With gloomy winter days, even south window may not be enough and some extra light should help. Even just getting a table/floor lamp with a CFL lightbulb that is at least 23W (equivalent to 100W), or similar LED bulb should help. Put it further away from plant at first, and slowly closer to acclimatize to better light.

A side note: apparently, this plant is very poisonous (many plants are to some degree)...so keep away from pets and/or kids :)

I agree with Rina.

Also with these, yellow soft falling off leaves is usually over watering.

Dried crispy leaves that fall off is under watering.

Thank you,

I did my best to repot it into perlite-grit-turface mix, as you recommended.

After finally freeing the plant from the container, it proved it had really dense root system, and almost no soil, only roots, very tangled, it was really difficult to plant it anew.

And the soil was, well, only soil.

I hope at least some of them will survive.

During repotting the plants have unfortunately lost a lot of leafs and some shorter stems - to be sincere, the looked really terrible... Now two months have passed and the shrublets have recently grown a lot of new leaves, I have divided them into two bigger containers, and they also got really green and dense.
Do you think that now everything is alright? :)

I see lots of new growth - that is a good sign. How is the light, did you manage to get some supplemental lighting?

Yes, I got a lamp and when the daylight gets dim, I turn it on and light the plant for most of the evening :) Thank you so very much for your help!!!

Your light exposure is not nearly enough, that's the #1 problem here. Best bet is to keep them cold and dry for now, so that they remain in a sleepy dormant state. If you keep them warm indoors and light is poor, growth will also be poor, which is what you're seeing. Then all hell breaks loose if soil is also poor and air is stagnant, it's a welcome invitation for pests.

I know you meant well and bought this plant to enjoy at home but it will be very difficult to grow well indoors. If you have a spot to keep it outdoors all spring, summer, fall it will reward you with excellent growth. Then in the winter something like a cold garage is a good storage place - if cold enough, you don't even need light for a few months, trust me.

Thank you, next winter I am going to put it into a garage where the temperature is lower. As for lighting, in the whole house I am using 5500K bulbs, 600W (really 125 but they are supposed to be an equal of 600), daylight like. Since a few weeks I am also using such bulb directly above the plant.