Introduce your kids to year-round gardening by letting them create their own mini greenhouse, or terrarium, out of recycled soda bottles. Kids can grow their own plants from seeds or from cuttings in their mini greenhouse. Any small plant will do: herbs, houseplants, flowers or even carnivorous flytraps. Plants that outgrow the mini greenhouse can be transferred to a larger pot or the outdoor garden. Building a greenhouse is simple, and kids can complete it in less than an hour with adult supervision.
Clean the 2-liter bottle by rising it several times with hot water. Remove the label.
Draw a guideline on the soda bottle with the marker about 6 inches from the bottom. Use this line to cut the bottle in half. If necessary, ask an adult to start the cut by making an incision with a knife or razor blade.
Fill the bottom of the bottle with a half cup of sand or gravel to provide drainage. Use playground sand, aquarium gravel or small stones picked up from a hike. If sand or gravel isn't available, crush an old clay pot and use that. (Let an adult crush the pot.)
Place a 1-inch layer of Spanish or Spaghnum moss in the mini greenhouse to keep the soil from mixing with the rock layer. Place a thick layer of potting soil on top of the moss, at least 4 inches deep or 1 inch from the top. Tamp down lightly with your fingers.
Plant the mini greenhouse with seeds or cuttings from another plant. Water carefully.
Fit the top of the bottle onto the bottom portion. Overlap the two bottles by at least 2 inches for a secure fit.
Place the mini greenhouse in indirect sunlight to avoid overheating. If the greenhouse appears too damp, remove the bottle cap to vent for 24 to 48 hours. Add water if the soil appears to get too dry.