A new technology that is becoming a reality for greenhouse production.
By: Kathryn A. Olson
Horticulture student, North Dakota State University
e-mail: katolson@prairie.nodak.edu
As a student of horticulture at North Dakota State University, I am very interested in the growing technology in regards to greenhouse production. One of the most innovative production methods being used today is hydroponics. Hydroponics is the "cultivation of plants without soil." It sounds impossible to those of you who have never heard of it, but hydroponics has become a serious consideration to many greenhouse managers. I will now take you through a definition of hydroponics, advantages of using it, different techniques that hydroponics entails, and certain crops to consider.
Definition of Hydroponics
As I stated earlier, hydroponics is the "cultivation of plants without soil." Since soil is the main nutrient provider to plants an alternative method must be utilized. A nutrient solution acts as the nutrient provider in hydroponics. This solution is the most important factor in the system. When mixing the different nutrients one must take into account the plants needs. Each plant is specific, so therefore the nutrient solution can be made specific. Also, the solution must be changed every two weeks because over time the elements are depleted or the water evaporates and the solution is too strong. The more often you change the solution, the better off the plants are. There are two types of systems: active system and passive system. An active system uses a pump to circulate water from a reservoir to the plants' roots. A passive system uses no pump and relies on a plants ability to bring the water and nutrients to its roots through its capillary action.
Advantages
1. Sterile medium (soil pests and diseases are minimized)
2. Necessary nutrients are available (producing healthier plants)
3. Plants mature faster
4. Use less space (roots don't have to spread out to find food)
5. Automation is easier (reduces time to maintain plant growth)
6. Water is reused, less lost to evaporation and run off
7. Can grow in places that usually can't with soil (example: desert)
8. Hydroponics water is always available so plant is never stressed.
As you can see, hydroponics has many qualities which are attractive to a greenhouse manager. The automation saves money, and the specificity of the nutrient solution allows for better quality plants. I believe that hydroponics can be a great way to grow healthy and happy plants.
Types of Hydroponic Systems
There are two main types of hydroponic systems: Water culture systems and Aggregate systems.
The Water culture systems:
1. Nutrient Film Technique-- The plants are suspend through holes in a plastic trough where a constant film of nutrient solution flows.
2. Aeroponics--Plants are grown in a container where the roots are suspended in a nutrient mist which clings to the roots.
The Aggregate systems: use some form of material to support and surround roots which allows good oxygen penetration to roots while retaining a layer of nutrients and water around the roots. Examples: rockwool, clay pebbles, gravel, perlite, vermiculite, sand or foam chips.
1. Flood and Drain method-- Plants are held in a container with an aggregate and flooded peridically and then drained to a reservoir.
2. Trickle Feed-- A solution is continuously flowing from a reservoir through a small tube which branches out into smaller tubes.
3. Tube Culture-- Plants are placed on all sides of a tube which is hung vertically and solutioin seeps through.
Crops to Consider
The use of hydroponics is especially beneficial for certain crops. Some of them are:
1. House plants
2. Ornamentals
3. Vegetables
4. Root crops (carrots, onions, potatoes)
5. Flowers (roses, carnations, orchids)
I believe that hydroponics is a system that can benefit a grower in many ways. These benefits are for home growers as well as commercial growers. Using hydroponics, we can grow better plants most efficiently. The fact that hydroponics is the "cultivation of plants without soil" almost seems absurd to the common person. I hope that by reading this and learning more about it, you can see that hydroponics is the wave of the future in greenhouse production.
Web sites that were useful to me in learning about hydroponics:
To try them out just click on them:
A greenhouse that uses hydroponics