In article , sacha
writes

We have S. confusa, S. hookeriana and S. digyna 'Purple Stem', so it's hard
to tell which is smelliest. But the one we picked and brought into the
house is confusa. I do think air temp. must have something to do with the
release of scent, and perhaps light levels, too. For example, the
Brugmansias we have seem to release the scent most powerfully at about 5pm
every day and the Impatiens tinctoria doesn't really perform at all unless
the sun is pretty strong.

My brugmansia smells far more strongly in the summer than it did in
December (flowering in the greenhouse) and I put that down to air
temperature. But clearly light levels (or something similar) must come
into play for all those plants, like night scented stock and nicotiana,
where the purpose of the scent is to attract night flying moths for
pollination.

--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/garden/