Hydroponics is a method of growing plants without soil. The plant gets all of its moisture and nutrients from a special solution of fertilizer and water. There are many different methods of hydroponic growing. Some require a growing medium to support the plant, while others grow the plant directly in the nutrient solution or a nutrient mist.
Advances in hydroponics are making the system popular for commercial and home use. Commercial growers can get more produce in less space using hydroponic systems. Home gardeners like the ability to grow indoors in a small space during the winter.
Advantages of Hydroponics
There are many advantages to growing in a hydroponic system, but the most important is the ability to grow plants on land that is infertile or not suitable for soil cultivation. Hydroponic systems use less fertilizer and water than soil-based systems because the water and nutrients are not wasted. Excess nutrient solution is returned to the holding tank and recycled for future use.
Plants in a hydroponic system have better access to oxygen, water and nutrients than their soil grown counterparts, so they grow faster and have higher yields. Soil related diseases are eliminated, so there is no need to rotate crops. Since seedlings are grown hydroponically, transplant shock is reduced.
Disadvantages of Hydroponics
Hydroponic systems are more expensive to start, especially when using commercial systems or automated systems. These costs can be reduced by hand watering the plants and using recycled household materials for growing containers.
Hydroponic systems require skill and knowledge for efficient operation. Plants grown in soil are largely dependent on nature for daily growth. Hydroponic plants are entirely dependent on the gardener for nutrients, water, air and possibly even light. Failure to properly regulate these can quickly lead to crop loss. Automation takes some of this responsibility from the gardener, but system failure or improper operation can be disastrous.
While hydroponic plants are not as susceptible to disease, when a disease does infect a plant it quickly spreads through the system.
How Hydroponics Works
Plants take in nutrients, water and oxygen through the roots. In a hydroponic system, a balance of these three must be delivered in the proper amounts precisely when the plant needs it, and in a form that is easily used by the plant. Nutrients are mixed into water and pH adjusted for optimal use by the plant.
In a simple system, the plant roots are allowed to dangle into the nutrient solution. This creates a problem because the plant also needs oxygen through the roots. The difference between hydroponic systems is in how the system delivers oxygen to the roots.
In bubble systems, the nutrient solution is oxygenated with air pumped through a bubbler. Flood and drain systems flood the roots to provide nutrients and water, then drain the water away so that the roots can get oxygen.
The nutrient film technique delivers the nutrient solution in a thin steam so that the top of the roots are exposed to air. The most complicated hydroponic system is the aeroponic system that delivers the nutrients in a continuous fine mist. The roots take in moisture and air together from the mist.
In delivering nutrients, water and oxygen, the hydroponic system fulfills all of the nutrition needs of the plant. Indoor hydroponic systems also provide warmth, light, and support as needed by the specific plant. (Reference 3 and 4)
Passive Systems Versus Active Systems
Hydroponic systems can be classified as active or passive. Passive systems use natural processes to deliver the nutrient solution. Wick systems in which the water and nutrients are drawn up by capillary action and water culture systems that allow the plants to dangle into the nutrients are passive systems.
Active systems require active watering. Ebb and flow systems, nutrient film technique, aeroponic systems and drip systems all require the nutrient solution to be passed over the roots and drained away. These systems can be hand watered by the gardener or use a system of timers and pumps to deliver the nutrient solution on a precise schedule.
Water Systems Versus Aggregate Systems
Hydroponic systems are also classified according to how the plants are supported in the system. Water systems such as water culture, nutrient film technique and aeroponics allow the roots to dangle directly into the water or mist. Drip systems and ebb and flow systems support the plant in a growing medium such as sand, gravel, rockwool and others to support the plant. The growing medium also retain moisture, keeping the roots from drying out.