Spider wrote:
Seeds contain their own food supply, which is enough to get them through
germination and the production of cotyledons (the first atypical leaves) and
the first 'true' leaves. After this, they need potting on, especially if
(snip)
If you're having trouble with moisture levels, try sprinkling a layer of
fine-grade vermiculite on the top of the soil after sowing. It will help to
retain moisture and will also help to stop the growth of algae on the soil
surface. It is naturally inert and sterile when packed, so should not
introduce disease. It allows light through, so you can even use it on
surface-sown seed.

That was really useful, thank you. I made a decision to put more effort
into growing from seed this year (I've been hit and miss over the past few
years, but we often end up just buying seedlings). Things normally start
out ok, then go pear shaped. This year they just aren't starting off at
all!