Growing plants without soil or hydroponics was first discovered in the early 17th century. With experimentation researchers of that time also learned that plant growth was enhanced with dirty water as opposed to fresh or distilled water. Using the correct amount of light, the appropriate temperature, water and balanced nutrients, plants experience more growth above the roots. As root systems do not have to extend to find nourishment, more energy is spent in developing other parts of the plant. Hydroponics is used by the backyard gardener to corporate farms to grow various crops including herbs.
The materials required to grow herbs by hydroponic method include a growing chamber for the root system, a means of transporting the nutrients to the roots, a reservoir for the nutrient solution, a pump for water circulation, timers for the pump and lights, and a lighting system. Some use growing medium to hold and stabilize the plants, but this is not essential.
Growing chambers are made from plastic bags with drainage holes to inverted soda bottles or plastic baskets inserted into the top of storage totes. Elaborate set-ups include large heavy-duty polyvinyl trays. This area holds the roots and is where the fertilizing solution will flow to supply hydration and nourishment. The solution is delivered to the roots using a variety of methods. Many use vinyl tubing or PVC pipe, but the fertilizer can be applied manually.
The reservoir is any opaque container to hold and store the solution. The system must be kept from light and closed to prevent microbial growth or pest infestation. Various types of pumps are used to take the solution from the reservoir to the plants and back again. Pumps are also used in combination with air stones to oxygenate water. Timers are used to provide continuous or intermittent nutrient flow to the root system and regulate light exposure.
Sunlight is the cheapest means of providing light essential to healthy plant growth. Fluorescent growth lights, metal halide or high-pressure sodium bulbs are used for artificial light and contain the proper wavelength and spectrum to ensure proper growth and development. The fertilizer used in solutions must be water-soluble and ready made hydroponic formulations are available. Increasingly, individuals circulate the water from a fish tank to hydroponic gardens as uneaten food and fish waste provide a nutrient rich fertilizer.
Clay pellets, coconut chips or fiber, pebbles, perlite, sphagnum moss and vermiculite are commonly used alone or in combination as medium to hold and stabilize root systems. Some retain water while others retain water and vital nutrients. In addition, the herbal root system must be kept at temperatures between 68 and 72° and have a pH of 5.5 to 7.0. Inexpensive thermometers are sold where aquarium supplies are located and pH testing and correction kits are found where aquarium supplies, garden supplies and hydroponic supplies are sold.
Various hydroponic systems vary as to how nutrient solutions are delivered to the herbs. An aeroponic system involves hanging the roots in the air and providing intermittent misting to keep the roots from drying. This system runs day and night, as does the drip system which supplies a larger amount of moisture and nutrients to the plants at one time. The ebb flow system operates by flooding the roots with solution and then allowing the mixture to drain.
The nutrient film technique or NFT suspends the plants over the solution reservoir. With the use of aquarium bubbling stones; the solution is circulated when air bubbles break the water surface. A simple water culture system is constructed by inserting herb baskets through a styrofoam tray and placing the tray directly onto the water/fertilizer solution. The wicking method involves placing the growth tray over the solution reservoir and allowing a wick (made of nylon rope or other material) to extend from the plant roots into the reservoir.