Self-watering containers provide superlative growing conditions for many common garden plants. If you have limited sunny space, poor soil or just enjoy the convenience of a low-maintenance garden, a grow box makes a ideal option. While purchasing a grow box can be expensive, a simple homemade version costs little. Reduce the expense even more by using recycled materials. Create your own grow box garden in less time than it would take to prepare and plant a small garden patch.
Collect plastic containers, such as empty 1/2-gallon milk cartons, nursery flats or pots. Purchase or recycle a 32-gallon plastic storage tub.
Poke holes in one side of the plastic cartons. Cut a long, wide slit down the opposite side. Place the cartons in the bottom of the storage tub with the hole-poked side facing up.
Drill a drainage hole on two sides of the tub just above the carton level. Fill around the cartons with a lightweight potting soil mix.
Create a fill tube with a piece of pipe or a water bottle with the bottom removed. The bottle or pipe needs to reach above the top of the tub. Place it topside down in a corner or along the side of the tub.
Fill the container with more potting soil. Place a black plastic trash bag or an empty potting soil bag over the top of the container.
Cut the center area out of the tub's lid, leaving only the rim. Snap the lid on to hold the plastic in place. The plastic blocks rain, conserves moisture and prevents weed seeds.
Make slits in the plastic when you plant. Fill the watering tube until water starts to come out of the drainage holes.