Patching and Plastering - patching small holes in ceiling

I have a 3-season porch and would like to repair / repaint the ceiling. It is pretty much ok except that the previous homeowners inserted 4 hooks in the ceiling for hanging plants. The hooks are secured by those bolts that have wings that pop out when you push the bolt up through the hole. So the hole they made for each hook is about 1.5 inches in diameter. I can look up into the holes.

What is the best way to go about repairing these holes? I've spackled smaller holes in walls before but don't know if a similar technique would work on this ceiling because (1) there's nothing for the compound to stick to because these are open holes with no backing and (2) I'm afraid that any repair will just fall right off because I'm working on a ceiling.

Any ideas for me?

Thanks!
Susan

I assume this is a sheetrock ceiling since you compared it to walls.
Cut some scrap sheetrock or wood narrow enough to fit through the hole but long enough to span it. You could put some joint compound around the lip of the hole and let it dry to secure your brace or screws through the ceiling which would give you a couple more small holes to fill. Once you have the backing you can build up layers of compound to fill the hole. Repeated thin layers will not fall.
You can usually build out from the edges of the hole also but it can be more delicate as you are trying to build it up w/o a brace.