Hang ceiling hooks for your plants in the wrong place, without the proper support, and you'll end up with a dropped plant, or worse, a large hole in your ceiling. There are two ways to safely suspend the combined weight of a plant, pot, soil and water. Thread a point-ended screw hook directly into a ceiling joist through the ceiling drywall, or use a small fastener called a toggle to support the extra weight where a joist is not available.
With a Joist for Support
Tap gently on the ceiling with your knuckles or your hammer's handle and listen. A solid, echo-free "thump" indicates that you are underneath a ceiling joist which should be able to support the weight of whatever you hang from your plant hook. Booming, echoing or hollow sounds indicate a poor location to hang the plant hook as there is no ceiling joist to support it.
Mark where you've decided to hang your plant hook beneath a ceiling joist with a small dot.
Tap a finishing nail straight up into the center of the dot you marked. Pound the nail as far into the ceiling as the threaded part of your ceiling hook is long, but make sure you don't pound the nail completely flush, or it will be difficult to remove.
Pull the nail out of the ceiling with the claw end of your hammer.
Place the pointed end of a threaded ceiling hook against the hole you just created. Screw the hook into the hole, applying slight upward pressure to get it started. Continue screwing the hook in until its base is flush with the ceiling drywall. You should feel some resistance as you screw the hook into the ceiling joist.
Without a Joist: Use a Toggle
Poke the screw through the hole in the ceiling hook, then thread the toggle on to the end of the screw.
Drill a pilot hole for the screw and toggle. A 1/8-inch toggle, which can hold 50 lbs. when installed on 1/2-inch drywall, requires a 3/8-inch pilot hole. A 3/16-inch toggle, rated to hold 100 lbs., requires a 1/2-inch pilot hole.
Push the toggle up through the pilot hole until you hear the toggle snap into position on the other side of the ceiling. Pull down slightly on the hook to hold the toggle in place against the ceiling as you tighten the screw. Keep tightening until the hook's base is flush to the ceiling.