In article ,
David W.E. Roberts wrote:

just planted up this year's batch of seeds - tomatoes, cucumbers,
courgettes.

I noted that the courgettes should be kept warm (20-25C) until they are
growing.

I think this is warmer than anywhere in the house apart from the airing
cupboard.

So how do you start off your courgettes?

This year ours just got put in the conservatory, which gets very warm
on sunny days, but is distinctly chilly at night. I don't know what
the temperature range is for definite because we still have lots of
things in storage for when we move in six weeks, but I'd say the range
could easily be from 25C during the day to 10C at night.

We had no problems with germination at all. In fact, using the room
as a large propagation house seems to have given excellent results for
all the vegetables we've planted this year -- we seem to have had far
more peppers and chiles germinate than previous years and we've always
found them to be fussy about temperatures.

I can't imagine there are too many natural environments where the
extremes of temperature each day are within 20C to 25C, so as long
as you're within that range for a significant proportion of the day
and never get too extreme a high or low, I wouldn't have thought
you'd have too many problems.

James