Hort oil is a petroleum based oil that has been used as a spray for dormant plants for many decades to get rid of scale and other harder to kill bug by coventional pesticide means. If keep in much sunlight it will likely cause some leaf and bud drop. If kept in the shade it might get thru OK. A mix of neem oil and vegatable oil might be safer. Follow the direction on the neem oil and add an eighth of a cup of any handy veggie oil you have per gal of water. This is a lighter dose than a dormant oil spray and about the same as a commercial nursery summer spray. I would still spray it in a shaded area and keep it there a few day. It would have been better to have done this a week or two before plans to bring in so you can check for new eggs of the white flies and do a second treatment which in bad cases are often needed. A magnifiying glass would help. I use a insect lens for checking for death of egg and any nymphs. Discolored is good. Clean and clear looking eggs, nymphs is bad. Google whiteflies to understand their life cycles and some of the ways to treat them. I hope this helps? Good Luck and
Happy Growing David

Thank you so much David for your detailed information. I grew up in the tropics and know nothing about growing tropicals indoors. I will keep your recipe for the lighter treatment in case the white fly returns - I hate to use those poisons be it indoors or out. Since it looked quite healthy, I sprayed with soapy water and left it half-covered in a large plastic bag for a few days, then brought it in and a few of the buds are beginning to open. Maybe I will get some blooms after all. I am considering cutting it back later in the fall and hope for more blooms next summer.
Northerner.

Last year when I brought my hibiscus indoors I brought along, spider mites into my sunroom and had a terriblke time eradicating them from my orchids, Is there are sure fire treatment that I could use to be sure it doesnt happen again this year?

Spider mites like plants that are not being watered enough, it makes their juices sweeter for sucking...so, make sure all your plants are kept adequately hydrated.

Mites also dislike air movement and moisture under the leaves where they hide, so daily spraying under the leaves is helpful. Indoors, a strong fan must be blowing 24-7.

And then there are chemicals and pesticides...