I use plastic foundation in all hives myself for the last several years. I've never sprayed them with sugar water but that certainly would not hurt at all. I would, however, put a feeder on them and check once a week to make sure they are drawing wax out correctly on the plasticell. Sometimes they start the drawing at the top ok but will slant the comb out away from the plastic as they draw. Whenever they do this, just scrape it off and they will go back to work and get it the way we like them to do it. Do not mix wax foundation or no foundation frames in the same box as the plasticell, as they will then ignore the plasticell as long as they possibly can.