Best Soil for Succulents?

[W]

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?

[David E. Ross]

I use 2/3 coarse sand and 1/3 peat moss with a very small amount of blood meal and a slightly larger amount of bone meal. For coarse sand, I go to a local builder's supply yard and buy washed plaster sand. To ensure the nutrients break down and become available to the plants, I also include a small amount of compost, which contains the necessary soil microbes.

[allen73]

Most commercial potting soils are too rich in fresh organic matter. Many growers use a mix of a low peat planter mix and pumice (50/50). Sand, small pebbles and vermiculite are ingredients added by many successful growers and hobbyists.

Mix a 4 quarts of medium grit sand with 4 quarts of perlite in your bucket. To this mix add 4 quarts of potting soil and mix well so that no dirt or clumps remain in the soil and make sure everything is loose. Add 'organic nutrients'

mix into the soil as succulents need a small amount of organic materials.

[Jeff Layman]

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.