Types of Hydroponic Systems
Hydroponics can be as simple as suspending a plant in a nutrient solution or a complex system with timers and pumps. Here we’ll discuss the most common types of hydroponic systems, noting which ones are more suitable for outdoor use and whether they are ideal for open air setup or in a greenhouse (sheltered).
Keep in mind, hydroponics doesn’t just mean growing plants with their roots hanging a nutrient solution. The concept of hydroponics really means a soilless growing system. While some hydroponic systems do actually suspend plants in fluid, others use an inert medium (containing no nutrients) such as coconut coir. For all the methods listed below seedlings would be started in rockwool cubes or seed trays filled with coconut coir then transplanted into these systems.
Common Types of Hydroponic Systems
Kratky Method
The Kratky Method is a technique where the plant is placed in a net pot (small basket) suspended over a nutrient solution. The roots will quickly grow out of the slits in the net pot and into the nutrients. There is no electricity or pumps needed with this method.
We grow peppers using the Kratky method, and tomatoes. This method utilizes a 5-gallon bucket for the reservoir. Top that with a hydroponic bucket lid. The only medium needed would be some Hydroton (clay pebbles) to hold the plant upright, especially in the seedling stage.
Small plants such as lettuce and other greens are usually grown over large trays. A large piece of Styrofoam (raft) is then placed over the top with holes made for net pots to hang through to the nutrient area. (see photo above)
This method is suitable for outdoor use whether or not the area is sheltered from rain. The small net pot does provide a potential path for small amounts rain to enter the nutrient reservoir. However, once the plants are larger the overhanging leaves make this less likely to occur.
DWC (Direct Water Column)
We listed this system second because it’s built on the Kratky method. Basically, it’s a Kratky system that includes an air pump pushing air to an air stone that is placed in the bottom of the bucket reservoir through a length of airline tubing. The aeration of the roots does produce superior results but the Kratky is a tried-and-true method that also produces excellent results if no power is available.
DWC is another system that can be used to grow peppers outdoors with or without shelter. You will however need a source of electricity for the air pump. If no power is available nearby, the Kratky method may be a better choice for you.
Less Commonly Used Types of Hydroponic Systems
Ebb and Flow
Ebb and flow hydroponics (aka Flood and Drain system) involves growing a plant, or plants, in a somewhat shallow tray or trough. A tray is usually filled with Hydroton or Perlite to support the plants. A reservoir filled with nutrient solution is kept below the tray. By means of a pump, the tray is flooded with nutrient solution and then drained over and over in intervals. The tray requires an overflow pipe to prevent water from spilling over the top of the tray. The overflow pipe will direct excess water back to the nutrient reservoir and help maintain the proper flood level.
While this method does produce good results it is usually better suited to plants that develop shallow roots, such as lettuce. This is not to say it can’t be used to grow peppers hydroponically. You will however need a deeper tray, larger pump, larger nutrient reservoir, etc.
As far as using this method outdoors, it would be better suited to use in a greenhouse or under shelter. The tray is completely open to catch rain water and would result in diluted nutrients with even modest rainfall making this method less than ideal for open air use.
Aeroponics
This method of hydroponics requires a system that suspends the net pots above a reservoir of nutrient solution. The roots are then sprayed with nutrient water at intervals, or constantly. The systems are easy to build and produce excellent results. If you’re handy be sure and check out our video on how to build a DIY Aeroponics System.
Using an aeroponics system outdoors is possible however there is a high likelihood that the rainwater could enter the system. As such we recommend using this type of hydroponics under cover or in a greenhouse.
Coconut Coir: Our Preferred Type of Hydroponic Systems
Of all the different types of hydroponic systems this is our preferred method for growing indoors and outdoors. Most people think of hydroponics as growing plants in a nutrient solution with little to no growing medium. However, any inert growing medium such as coconut coir provides an excellent environment for growing peppers, tomatoes, eggplant, or other large, deep-rooted plants.
For this technique you’ll use either a 70/30 or 50/50 mix of coconut coir and perlite. The ratio of perlite you use will affect the number of times you’ll need to water; less coir requires more watering. You’ll also need to set up a drip system that runs off a timer to feed the plants several times a day. Once every two weeks you’ll need to flush the buckets with plain water to rinse away any mineral salts that may have accumulated. We love using this method for growing our peppers. If you’re interested in using this method, we put together a video about our system which we feel is the best outdoor hydroponic system.
Growing hydroponically in coconut coir can be done indoors or outdoors in open air with no worries of rain. In fact, with this method, you’d actually benefit from some rain which will aid in rinsing away mineral salt buildup.
If you’re curious about what type of fertilizer to use with these systems then check out our post discussing what we’ve found to be the best hydroponic nutrients for vegetables.
Conclusion
We haven’t included every type of hydroponic system here but we did discuss the most common and the most effective methods. If you have any experience with growing hydroponically indoors or outdoors, we’d love to hear your thoughts in the comment section. Feel free to post questions as well.