If you'll be away from your hanging potted plants for a few days, irrigate them in your absence with a self-contained, home-made drip irrigation system. The water will slowly seep into the potting soil, keeping it from drying out until you return and can resume your normal watering schedule.
Remove the cap from the empty plastic soda bottle. Rinse the cap and the bottle in clear, running water. Set the bottle aside.
Place the bottle cap on a scrap of wood, with the flat side down.
Drill five to seven holes in the top (not sides) of the bottle cap, making the holes evenly spaced.
Fill the empty soda bottle with clean, fresh water. Screw on the cap with the holes you drilled in it in Step 3.
Push the butt end of the handle of the garden trowel or large-diameter dowel into the soil of the hanging plant to make a hole about 1 inch deep.
Place the top of the filled and capped soda bottle into the hole in the surface of the soil you made in Step 5. Tilt the bottle slightly so it is not straight up and down, but slightly tilting.
Allow the water to slowly seep into the soil.