Step-by-step tutorial
Step 1
Drill a hole in the water bottle cap with the 1/8" (.3 cm) drill bit. Ask an adult for help!
Step 2
Fill the bottle with water and turn it upside down next to the plant you want to water.
Step 3
Work the bottle into the soil to stand it up. Refill the bottle as needed to keep your plant happy.
Final result!
If the water drips too fast, partially block the hole with putty, or just make another dripper with a smaller drill bit. If it drips too slowly, drill the hole slightly larger.
Keep tinkering, and you'll have an amazing (and amazingly cheap) irrigation system running before you know it!