One of the simplest, most affordable grow pot systems is easy to make with a few 2-liter soda bottles. In addition to the bottles, perlite is used as a support medium for the roots. One type of system needs a piece of yarn to serve as a wick and the top of the bottle to hold the plant. The other type uses a Styrofoam coffee cup filled with perlite as a place for the plants to grow.
A homemade hydroponic pot system can use many different types of nutrient solution to meet the plants' requirements. Commercial nutrients are available that contain everything plants need and can be adjusted for different types of plants as well as different stages of growth. Some of these solutions can be fairly expensive while others are more reasonably priced. An inexpensive, good-quality nutrient solution can be made at home by mixing water-soluble fertilizer and Epsom salts with water.
The soda bottle pots need to be cut off and filled with nutrient solution. The wicking system requires the addition of a piece of yarn and some perlite to complete the simple setup. The yarn brings the nutrients up to the plants. In the homemade air gap system, a Styrofoam cup is filled with perlite and suspended over the nutrient solution. The roots of the plant grow into the liquid, but a space is left between the bottom of the cup and the top of the liquid, providing the air gap that supplies the plant with access to oxygen.
The best plants to use in the soda bottle pot system are those that tend to grow fairly quickly and don't grow too big before they can be harvested. Many leafy herbs will work, such as peppermint and oregano. Leaf lettuce and spinach are also good choices. A series of these grow pots set in a bright, sunny location will provide a constant source of herbs for the kitchen or greens for the table.