On 10/02/2013 02:33, W wrote:
I am trying to find the best soil for succulents in a Mediterranean climate.
For the pots I have planted so far, the mixture where the succulents seem to
grow like weeds and just love the soil it is about 1/2 fir bark and 1/2
sand. I read online that several people recommend 1/3 fir bark, 1/3 pumice
(I assume that is replacement for the sand?), and 1/3 Drystall (to absorb
and retain moisture). What do others have success with?

The 1/2 fir bark and 1/2 sand mixture is always dry on top and slightly
moist if you poke your finger a few inches into the soil. I didn't think
succulents liked soil that stays moist? However all of the plants I have
tried in that soil appear to really thrive.

In terms of fir bark, is there a particular brand or guidance on sizing of
the bark I should look for?

It's not clear if you are growing these outside all year round or are
able to give them some cover. You note that succulents don't like soil
that stays moist. True most of the time, but the main rule is that
succulents don't like to be cold and moist at the same time. Many
succulents are happy down to freezing or even slightly below if
completely dry.

So your soil needs to reflect those conditions. I understand a
Mediterranean climate to be fiercely hot in summer, cool/warm (but not
cold) and wettish in spring and autumn, and cool to cold and possibly
wet in winter. Now if your pots are out all year round, then they will
need a very free-draining mix, but if you can keep them out of the rain,
then the actual soil makeup is not so important if the pots are kept dry.

So, if not under cover, I would go for 3 parts sharp sand, one part 5 -
8 mm grit, and one part of soil or any compost (I don't think its
important what type; I tend to use old soil/compost that other plants
have grown in for one or more seasons. Succulents aren't usually gross
feeders needing very fertile soil. You can always water then in summer
with a liquid fertilizer if you think they need it). However, if you
can keep your pots dry, and out of any rain, then even ordinary soil
should be ok providing it's allowed to dry out at the end of summer
before the rains come.

--

Jeff