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Easy Hydroponic Systems That You Can Make at School

Hydroponics, the art of cultivating plants without soil, is gaining popularity as a scientific concept, agricultural technology and hobby activity. With the proper knowledge and a few basic materials, anyone can set up a hydroponic system and try their hand at growing nutrient-rich produce. Learning about hydroponic production hands-on can help students better understand the food system, plant science and more. School hydroponic systems can become a key focus for your school, as students grow nutritious produce for use in the school cafeteria or in cooking classes.

This blog will explore two easy school hydroponic systems: the Kratky method and the Deep Flow Technique. These methods require minimal equipment and are suitable for students looking to venture into hydroponic gardening.

Easy school hydroponic systems aren’t hard to come by, but the best methods can optimize performance or control the growing area more precisely.

Basics of Hydroponic Systems

Instead of relying on soil, hydroponic systems utilize a nutrient solution and a growing medium to foster plant growth. The nutrient solution is water mixed with a liquid fertilizer, containing all the necessary macro and micronutrients plants need to develop. The growing medium supports the stem and roots of the plants. In traditional agriculture, plants get their support from soil and the microbiome around the plant.

The Kratky Method

Due to its passive nature, the Kratky method is a popular choice among beginners in school hydroponic systems. Unlike other systems, it operates without pumps or the need for moving air or water. It was created in the 1990s by Dr. Bernard Kratky, Emeritus Horticulturist at the University of Hawai’i at Manoa. He first proposed the system in Acta Horticulturae in 2009, writing about a hydroponic growth method that could work without electricity. In this system, the plants and growing medium are held by a net cup, which sits in an opening on top of a reservoir of nutrient solution water.

The Kratky Hydroponic Method diagram
The Kratky method can be done in jars and containers of many sizes, but Dr. Kratky recommends short and wide containers over mason jars like this system. The benefit of Kratky’s system, however, is that you can grow plants hydroponically in just about any container. You might just have to make some adjustments to ensure that the growing roots can always reach nutrient solution.

How It Works

The plants can receive oxygen from the tiny space between their netting and the water’s surface. This helps prevent root rot, allowing air roots to absorb oxygen from humid air.

The Kratky Method is often called a “Fill and Forget” system because as crop roots grow longer and suck up more water, the nutrient solution levels in your reservoir decrease. Ideally, this will work to give you an indication of when the crops will be nearing maturity.

How to Make a Kratky System

To create your own, you need:

  • Sprouted plants
  • A container
  • Net cups
  • Growing medium
  • Nutrient solution

Low and wide reservoir containers are generally more suitable than tall and narrow reservoirs, which may shock your plant, as roots may not grow fast enough to reach the dropping level of nutrient solution. While mason jars can work, Dr. Kratky recommends a larger tank because it allows for more room for roots to grow and expand and does not have to be refilled. 5 gallon buckets and 10 gallon tubs are some of the most popular choices for Kratky systems.

When using a bucket or tub, drill holes big enough for the net cups in the lids. You can purchase net cups online or construct some by cutting slits in the bottom of a disposable cup.

Place the net in the container’s opening. Fill it with a growing medium and transplant the sprouted plant into the net. Mix the nutrient solution with water and pour it into the container until the water level is just below the bottom of the net cup.

Don’t refill your Kratky system until your plants absorb all the nutrient solution water or are ready for harvest. Be sure to leave room at the top for oxygen when refilling. Ideally, you’ll want to fill the nutrient solution reservoir only once. The stagnant water may attract pests and algae, so secure the lid tightly and ensure you use a light-proof container.

The Kratky method is incredibly easy for students to set up and understand, and is a great introduction to school hydroponic systems.

Deep Flow Technique (DFT)

The Deep Flow Technique (also known as Deep Water Culture) is another simple hydroponics technique. It suspends the plant in a nutrient-rich solution that is continuously recirculated. It works well for plants without extensive root systems and crops with quick turnaround times. School hydroponic systems can make use of the components used in this system (Air pump, air stone, water pump) for a broad range of other systems.

How it works

Plants are suspended in a nutrient solution, held in place by a floating platform or raft that rests on top of the water. An air pump and air stones are used to oxygenate the solution. They provide a constant supply of dissolved oxygen to the plant roots. This is where the system differs from Kratky’s. In the Deep Flow Technique, plant roots are wholly submerged, and the nutrient solution level in the reservoir will recirculate to the growing tray above.

A diagram of a DFT school hydroponic system.
Unlike Dr. Kratky’s system, the Deep Flow Technique (DFT) is an active hydroponic system. It needs electricity for the air pump, air stone and water pump. Plants rest on the surface of the water, and there’s no room for air between the raft and the nutrient solution. Because of this, the water needs to be oxygenated. If you made this system without the necessary equipment, you might run into plant problems like root rot that are caused by a lack of oxygen.

How to Make a DFT System

1. Picking a Container

Start by selecting a suitable container to serve as the reservoir for your nutrient solution. It should be lightproof to prevent algae growth and have a lid to support the plant net pots. The size of the reservoir depends on the number of plants you intend to grow. Bigger containers will have room for more plant sites.

2. Air Pump and Air Stones

You’ll need an air pump and air stones to oxygenate the nutrient solution. Attach the air stones to the pump and place them at the bottom of the reservoir.

3. Net Pots

Then, obtain net pots. The same net pots that worked for the Kratky system can likely be used in Deep Flow Technique systems. Fill them with a suitable growing medium, such as peat moss or lava rock. These mediums help support the plants and allow the roots to reach the nutrient solution.

4. Preparing Nutrient Solution

Prepare a nutrient solution according to the requirements of the plants you are growing. You can find hydroponic nutrient solutions specifically formulated for different stages of plant growth. Follow the nutrient solution package instructions and mix it with water in the reservoir.

5. Planting Your Hydroponic Crops

Next, plant your seedlings or clones into the net pots filled with the growing medium. Gently place the roots of the plants through the holes in the net pots, allowing them to hang down into the nutrient solution. Maintain the system by ensuring the water level in the reservoir remains constant. It should cover the roots but not submerge the net pots entirely. Monitor and adjust the pH and nutrient levels regularly to provide optimal conditions for plant growth. The air pump should run continuously to oxygenate the solution.

Finally, you’ll need to provide sufficient light for your plants. Depending on the type of plants you are growing, you may use natural sunlight or artificial grow lights. Ensure that your plants receive the appropriate light intensity and duration.

Additionally, you’ll want to regularly clean and sterilize your school hydroponic system every 10-14 days to prevent the growth of algae or the spread of diseases. This includes cleaning the reservoir, changing the nutrient solution, and periodically sterilizing the growing medium.

A closeup of a green leaf.
Many hydroponic plants receive their light by absorbing full-spectrum grow lights instead of sunlight, although outdoor hydroponic plants are not uncommon.

Advanced Hydroponic Methods

Now that we’ve explored some simple hydroponic techniques, such as Deep-Water Culture and the Kratky method, let’s delve into more advanced methods that offer further versatility and control for school hydroponic systems.

Here at Pure Greens, we utilize sophisticated hydroponic growing methods intended for commercial production. These farms are a lot larger than the previous methods can handle, so we had to find different growing techniques to maximize the output of our custom shipping container farms.

The most significant element we’re trying to control is the growing environment. Everything we’ve talked about so far is exceptional technology that allows growers to foster plant growth without soil. But the one thing that prior methods lacked was climate control. Our systems add an element of controlled environment agriculture that provides just that.

Like DFT, our system is active, using pumps and air stones. To optimize this, we want to look at the factors that affect the growth rate of plants. High levels of humidity and heat are detrimental to plant health, attracting pests and increasing bacteria growth. Diseases like root rot can develop and inhibit plant growth at the root zone.

In warm environments, lettuce can bolt when daytime temperatures exceed 75 degrees Fahrenheit, producing flowers that form seeds. Similarly, plants can be negatively affected when things are too cold, stunting development, delaying flowering and reducing harvest volume.

Because of this, our systems utilize strong industrial HVAC units, allowing for precise climate control. When you can precisely control the growing environment to a specific level, you can optimize for faster or more specialized production.

What’s Next

By implementing hydroponic studies in schools, students gain firsthand knowledge of different types of produce and witness the entire growth process from seed to harvest. This experiential learning fosters a deeper understanding and appreciation for healthy eating as students become more connected to the food they consume.

When established as part of a school lunchroom, container farms can introduce students to lesser known or specialty crops that might not be readily available in traditional cafeteria settings. This broadens their culinary horizons and encourages them to explore more diverse textures and flavors.

One of the key advantages of container farms is their ability to provide a controlled growing environment. Industrial HVAC units allow these systems to hone in on precise regulation of temperature, humidity, and other factors that affect plant growth.

School hydroponic systems can maximize production and ensure consistent yields of high-quality produce by maintaining optimal growing conditions. This supports the school’s cafeteria needs and can generate surplus crops that can be donated to local food banks or used in educational programs.

Furthermore, container farms are space efficient. Repurposed shipping containers can be installed anywhere with a power connection. This versatility enables schools to incorporate agricultural education into their curriculum, providing students with hands-on experience in science, technology, engineering and math (STEM) subjects.

A thick green leaf spotted with water droplets.
Hydroponic systems can reduce water usage by as much as 90% compared to traditional methods.

Curious about Container Farms?

If you understand the value of hydroponic growing, you will appreciate it in its many different forms. From easy, no-power-required systems like the Kratky Method to more complex procedures like Deep Water Culture, the fundamentals of hydroponics don’t change.

If the climate is controlled, as it is in our container farm units, crops can be grown year-round, regardless of outside weather or conditions. That’s a benefit that your students will appreciate when they can eat new varieties of fresh, nutritious produce every season of the school year.

Container farms can also be a great way to introduce science concepts to students. Because the industry is rapidly evolving, the farmers of the future will be required to understand a variety of different growing systems. By lighting a spark in young green thumbs, you can create a lifelong desire to learn more about how the produce we eat daily is produced and cultivated.

Curious about how a container farm might fit into your school community? Talk with us today, and we can help you identify the school hydroponic systems that will work for you.