On 13/05/2020 15:34, David wrote:
I tend to use Multi-Purpose for everything, but my first lot of sowings of
small seeds look to be struggling a bit with the large particle size.

Rub the stuff slightly or sieve it to make sure there a no big lumps.

Do all seed and cutting composts have a smaller particle size, and does
this make a big difference?

The main difference is that there is a bit too much long term nutrient
in the general multipurpose compost for young seedlings.

It is worth cutting it 2+1 or even 1+1 with a washed sharp sand or
perlite/vermiculite to make it freer draining and slightly more friendly
to germinating seeds. I find it really only matters with the finest and
tricky seeds - I normally plant anything robust in multi-purpose.

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Regards,
Martin Brown