I don't know about D. spathulata, but D. adelae is the queensland
sundew. You may know this. North Queensland is Nep country.
therefore, grow D. adelae in Nepenthes conditions and it will act as if
it was at home in queensland. My plants (grown in highland Nepenthes
conditions) are in full-late flower now, and all 3 flower scapes
appeared at once. I would guess this to be co-ordination. As for the
seasons, they just know when it's spring. I wouldn't worry about
erratic flowering.
I suppose that also answers the question about the dormancy, D. adelae
is OK without any 'dormancy', and I would guess any other sundews from
places such as Tropical East Africa (if I can remember rightly I think
D. cuenifolia amongst others (the complex petiolaris comes to mind ) but
I might be (i.e. probably am) wrong.
KR's
Toby