My wife's favourite, *favourite* annual is Cosmos.

This year, all her seedlings came to nought: they were already pretty
weedy when she set them out, but since then the vagaries of the weather
have made them all lose the will to live: the stunted remains, with
small weedy flowers, had to be pulled out last weekend.

She has sown from seed into trays for years and years, usually with
spectacular results around this time of year. We can't guess what she
may have done wrong this year, but for next January/February ....

What is the best way to grow from seed? My wife sows them indoors in
trays, and places the trays in front of a south facing window; they
usually germinate well (but to my own eye) they always grow up rather
leggy.

She moves them to the greenhouse (unheated) when the weather warms up,
and when they're big enough she transplants them to individual small
plastic pots. She plants them out in April.

Questions I have a what are the dangers of over-watering (could that
be the cause of legginess? And: what's the best sort of compost to use
for annual seeds?

We're in Tynedale, Northumberland.

John