On 10/01/2011 17:19, Sword wrote:
Hi all,

I wonder if you could help me please as my son thinks his cacti are
beginning to die and he really loves them.

They have been in his bedroom for about 4 years and nothing I can think
of has changed (watering habits same, temp same, etc etc).

It has been very cold recently and the first leafy stemmed one looks to
me like a succulent Euphorbia and they are somewhat tender. I suspect
frost damage from cold air drafts running down the inside of the window
(actually below 4C is probably enough). You could try taking a cutting
in early spring in case the thing is rotting at the roots.

Beware of the white latex sap when taking cuttings it is caustic and
incredibly irritating to the eyes. Pieces will usually come away where
it joins the main stem with only a tiny wound. Take care!

Go easy with the water. In a centrally heated home they do need some but
the compost should be allowed to go dry between waterings in winter.

Yet, as can be seen from the first pic, they seem to be going brown from
the bottom - and the second pic shows that his big one is now going the
same way (just moved it downstairs to try and save it) ...

The other is an opuntia which should be as tough as old boots. I'd
suspect over watering if it really is going brown and soft at the base -
they tend to go corky naturally with age as they get bigger.

BTW the spines on this cactus can be very annoying. Invest in a decent
pair of tweezers (good advice for all cactophiles)!

Any clues please? We have some black mould in the shower and on some
windows - would this be it??? Room is North facing.

North facing and cacti is not ideal. The plant still in growth is
showing signs of etiolation - going weak straggly growth searching for
the light. Your son might like to join the local branch of the BCSS
where small plants that will flower when young plants and seeds are
available to younger members at pocket money prices.

http://www.bcss.org.uk/

Rebutias, Notocacti, Mammillaria and Lithops include some nice small
plants that are easy to grow and will flower in 2-3 years from seed.

Many branches have a stall at the local summer show(s).

Regards,
Martin Brown