Jangchub wrote in
:

Forsythia is cold hardy in your zone. If the hibiscus has
shiney foliage it is tropical and will not really do well
in the house. They are very prone to white fly indoors. I
don't know where the white fly comes from, but they do.

i had no problems with my tropical hybiscus for 10 years. no
white fly, no aphids, nothing. it grew like crazy & i had to
prune it severely at least twice a year to keep it contained.
however, my hybiscus was growing in a high humidity tropical
set up with my Hooded Chamelion. i was specificly aiming for a
particular temperature & humidity range suitable for Pooh. it
also seemed to be exactly what the hybiscus enjoyed too, which
was a bonus (nothing like seeing those huge red blooms when
you wake up in January).
then again, i've never had a problem with white flies ever &
i move plants in & out every year... i do wash them off when i
bring them in, but i don't repot unless they need it, or
fumigate the soil or use pesticides.
lee