You need first of all to ascertain which Hibiscus it is.
If it is a tropical Hibiscus you will need to put it in the sunroom when it is below 40 degrees outside. If it is hardy, you can probably leave it out, although I would still have it inside if it gets really cold in winter where you are.

The hardy type will survive year round outdoors. It will have medium colored dull green leaves. The tropical variety- dark, rich green shiny leaves- will need to brought in for the winterdepending on which zone you live in. Hope this helps.

I wish I had read this post before I went and bought two tropical hibiscus thinking they were hardy hibiscus and planted them in the ground.

Proudgm,
all is not lost, don't get upset.
Just dig them up and pot them when the nights get under 40 degrees where you live, that's all.
THey will enjoy the summers in the ground, in the sun.
Mine are planted in the ground and doing too well, LOl, getting hughe!
But the end of September, beginning of October, the party's over and they will come in their sunny winter room.