I grow several aeonium including this one, I keep mine very dry and cool through the winter, but other than that they have to take their chances. Some will take a little frost, and have come through the winter outdoors here, but I've not tried that with A arboreum 'Zwartkop' (or 'Schwarzkopf' as it's also known).
I think this is the same one that MickC very kindly gave me last year.. It's been in a greenhouse all winter with only frost protection heating and no water at all. I've just noticed it's sprouting in a couple of places from the stem so I'm going to start watering very sparingly from now on. Maybe you were too kind to yours!
if your stems arent rotted all the way up,cut the rot off and dry out for a couple of days. plant them back up and they might grow again.very easy plant to propagate, when they get too big,chop them back and plant the cuttings as above,the stem will re-shoot with several heads too
they are very easy to propagate from cuttings , in fact most of those on ebay are done that way.
it looks like you bought some like i did, stem cuttings minus roots. once these callous over then in slight damp compost they will romp away.
thy don't like or need much water in the winter, they are very shallow rooting, only the top 3 inches or so
you will also find LOTS of cross breeders, they are easy to do and give wide and varied results
all bar a few are from e bay and all doing fine, in fact they are now flourishing in the greenhouse, with new growth clearly visible.
the darker leaved types are more prone to leaf drop in the winter i find, as they revert to green from the lovely dark rich colours in summer.
they can go out after the last frosts, so up here mid may ish, and you can feed them with a liquid feed every fortnight or so, if planted out mine just love to bake in the sun, after all they come from the canaries mainly and africa.
I had masses of the zwartkop, all propagated from what was a two inch high cutting I had many years ago, one of the cuttings was a multi stemed plant over 5 foot high and it flowered last year.
I take good sized cuttings to use each year but I left most of the outside ones to die this winter, I had the cuttings I wanted and it got to the point where no one wanted them at the meets anymore so it wasnt worth keeping them, shame really but if no one wants them then they cant take up valuable greenhouse space.
I thought looking at the list you were going to say these are varieties out there Then I saw they are yours..wow..quite a collection.
I bought off Ebay all three plants. Once the actuall leaves came away in my hands I never looked for a root I was too disapointed and mad. Gardening is expensive as you know Dave and each one costs me £8, so £24 and still have no plant but I will buy another after may, give it a starter for ten in the sun.
I like them. I saw my first one at Botanical Garden forums. I left there then found here
like the agave's , a gritty mix of compost is pretty much the norm
they will drop the lowest leaves even when in full health, its when the upper ones start ot go you've problem.
the roots are very fine, and can rot easily. in that case don't bin it, cut the stem back into fresh green growth, and let this heal over for a few days, then in a very gritty mix, insert the stem in a distance, (depends on the size of whats left how much you have to push in)
a sprinkling, even a slight mist over the compost just to settle it in, then leave it.
they don't need too much warmth over winter, but MUST have as much light as possible.
it could be that was why they croaked, but really they do grow from a stem...
I've got some from a plant which keeled over in October, and took about 8 cuttings from it, all are now pushing roots out the bottom of the pots
I have learned a lot in the short time I have been here about plants I 'just hoped' would do well without even looking to see how to care for them. Having 'green fingers' with our normal plants and thinking pf being able to raise the tropicals in the same way is heading for the disater.
Ade, I've never seen yours at meets. I 've had one a couple of times and bought one at Akamba last year. It is in the poly which went down to -1.9C before I rigged the heater up. Now stays at 1.3C lowest. Is kept completely dry in ballast with a small amount of JI no3. Has lost a few lower leaves but is fine. I have a 160w mercury lamp that switches on when low rate tarriff cuts in at 2am and is on until 8am so the Agaves, Cacti and succulents are getting about 17 hours light at the moment.
Dave2166 you dark horse a secret Aeonium hoarder What else you hidding away there
My rose one which was meant to be the most hardy mushed in -5.6C under the canopy of my big Chamaerops but the blue ones are fine out in the open.
have to agree,an impressive collection
so far only lost the dinnerplate this year, not too bothered if the zwartkops die,theres so many here. had some that grew way too leggy,cut them down to the right height and chopped the stems up,drew arrows so i knew which was top and planted them,they all grew using daves method.you only need one strong plant to make loads
Dave Brown wrote:
Dave2166 you dark horse a secret Aeonium hoarder What else you hidding away there :
a ''few'' agaves, nothing too exotic. since i got the greenhouse in the autumn i thought i might as well get a few plants, and when i started to look at aeoniums i relaised what a diverse genus they were. and provided they are kept frost free are now easy to keep going over winter..
and a piece of cake to prop, as i shall be doing then selling them on ebay, later this year
Then I saw they are yours..wow..quite a collection.
but the blue ones are fine out in the open. 
