Hydroponic Technology
Grow Cheap Food the Kratky Way
This passive hydroponics works great for folks on a budget.
Lack of access to fresh, local food is a cause for concern within rural and urban areas. Of course, many want fresh, wholesome food, but factors such as low wages, lack of transportation, and distant grocers exacerbate this problem.
In addition, as populations become more densely packed, we have little to no land of our own to grow our food if desired. Community gardens provide one solution, but another answer may rest in horticultural methods like hydroponics.
Hydroponics differ from conventional agricultural methods in that they require no soil. Instead, plants grow in water-based, nutrient-dense solutions. As lands become less fertile due to overproduction and a changing climate, these methods enable food production to occur indoors — where one may precisely control conditions.
Because of this capability, urban farmers may choose to employ hydroponic setups within multi-level buildings. Small producers could grow on balconies, in kitchens, or even on rooftops. Another advantage is the ability to grow year-round.
Proponents would recommend growing in water for other reasons, too. For one, the nutrients are more readily available to the plant. In addition, plants expend less energy by needing less extensive root systems. Notice that plants often grow faster hydroponically and yield sooner than soil-grown counterparts with the same genetics for this very reason.
You most likely found your way here because you want to grow your food using a novel, modern method at your residence. Let’s focus specifically on an inexpensive form of hydroponic horticulture called the Kratky Method. Individuals who set up a Kratky system appreciate it for numerous reasons; some of these reasons include its ability to be used outdoors, its minimal use of electricity, and its low cost.
We will discuss different aspects of the Kratky Method. Though far from exhaustive, we need first to understand what hydroponics is. We will learn about Dr. Bernard Kratky, as well as break down the components of his system. Then, we’ll find materials, set them up, and learn how to put them together to get you growing! Keep reading to find out how.
What is hydroponics?
Before defining hydroponics, we need to review its realm of study. Horticulture is the practice of cultivating gardens to produce food, medicine, ornamentation, and comfort. In contrast, agriculture focuses more on industrial-scale applications, and it typically features large or even vast plots of single-type crops.
Since horticulture concerns itself more on a smaller scale, you tend to see more mixed-crop operations. Horticulture takes numerous forms, such as olericulture (vegetable) or floriculture (flowering ornamental). But, our focus today is a small subset of the entire field — hydroponics.
A standard view persists that hydroponics only recently developed. While it remains true that organizations such as NASA have significantly contributed to the field of hydroponics, this practice existed in many forms across countless human cultures since before recorded history. From the floating chinampas that fed the ancient Aztecs to the Hanging Gardens of Babylon — a great wonder of the world — human beings have long employed the practice of growing crops in not just soil but water, too.
Farmers make use of hydroponics in many ways. Different types of hydroponics systems exist; some examples include the wick system or the ebb and flow system. However, today we examine a variety of Deep Water Culture (DWC) known as the Kratky Method.
DWC methods work by placing plants in a suspended net pot above nutrient-rich, oxygenated water. Typically, one would use an air stone to keep the water oxygenated. Read on to learn how the Kratky Method oxygenates your plants without an air stone or water pump.
What can I grow?
Many things grow well via hydroponics, and some do not. Leafy greens such as lettuces and spinach work perfectly for this setup. Tubers and others that fruit in the ground like onions or carrots prove less than ideal.
Depending on reservoir sizes, you can grow some larger varieties such as tomatoes or peppers. They may require some trellis for support or have more significant water needs.
Other options include strawberries, herbs, and even some beans. You can’t grow things like trees or indeterminate varieties, but you can keep a steady supply of salads and seasonings. Feel free to experiment to see what works best for you and find what tastes you like.
There are no mistakes when you’re learning, and you can also transplant anything into the ground as it gets too big for its container. Next, we will discover who spearheaded the development of the Kratky Method.
Who is Dr. Kratky?
Before we move on, let us first review who came up with this unusual method of growing. The University of Hawai’i has employed Dr. Bernard A. Kratky as a professor emeritus since July of 1971.
He specializes in vegetables, hydroponics, culture & management studies, and one of his claims to fame includes research into non-circulating hydroponic methods using suspended net pots. These methods benefit places of the world that have poor soils and limited access to electricity.
What is the Kratky method?
First published via research paper in 2009, the Kratky Method strives to bring hydroponics to the masses. This method is one and done, and it requires little to no effort after setting it up. The plant grows as it absorbs water and nutrients from below. As the solution goes down, so do the roots grow down with it.
Because of the simplicity of this system, the size of your reservoir limits how long you can grow. Some gardeners extend growth cycles by “topping up” on the water and nutrients when they get low.
Several growers find adding water and nutrients to halfway refill the reservoir to be effective in extending a Kratky system. If you add water, recall some nutrients will remain in the reservoir before calculating how much to add.
Through extensive research spanning decades, Dr. Kratky and his team developed a system of hydroponics that is self-sustaining, requires no electricity, and can be composed of upcycled materials.
To get started, we need to first mention the needs of your plant, and then we can explain how the Kratky method fulfills those needs. All plants need a few basic things to thrive so be sure to consider these when getting started: light, oxygen, nutrients, support, and water.
Light
Determine where you will grow your hydroponic plant ahead of time. For example, are you growing this container outside on a balcony or patio? Or instead, are you growing it in a window sill or under a grow light? Using the sun as your light source costs nothing compared to purchasing a grow light.
You can get the best of both worlds by growing inside your house next to an east- or south-facing window. Some lettuce or greens may be perfectly happy with less light, but a tomato or pepper plant might prefer something more intense, like 6–8 hours of direct sunlight.
Additionally, your Kratky setup can vary in size from being a mason jar to a 5-gallon bucket. Consider this when thinking about placement, too. If using a clear container, be sure to block out the light from entering.
Before you begin, paint the container black, put a sock around it if small, or wrap it in aluminum foil. Light entering the water reservoir encourages algal and bacterial growth — which can inhibit plant growth.
Oxygen
“Wait, but I thought that plants breathe in carbon dioxide?” That is true, but they also uptake oxygen from their roots and leaves for respiration — similar to us. Usually, plants meet that need through little pockets of air found in the soil, so hydroponics setups regularly include a water pump or air stone to dissolve oxygen in the water.
The Kratky Method oxygenates your plant’s roots by leaving a small gap between the suspended net pot and the nutrient solution. As the plant roots grow and develop, they reach down into the water — leaving the top of the roots exposed. This interchange encourages the development of “air roots,” which absorb oxygen.
Nutrients
What do you feed your hydroponic plants? Plants produce their food via photosynthesis, where they convert sunlight to energy in the form of sugars. Yet, they still need other nutrients or minerals. Horticulturists refer to the elemental NPK — or nitrogen, phosphorous, and potassium.
While plants do require trace amounts of several other elements, you can typically find that in a store or online. It is possible to mix your own, but newbies can use a premade solution by General Hydroponics or FoxFarm. One will incur a cost to purchase the nutrients, but they will last a good while before being replaced.
Support
Another aspect to consider is support for both the roots and potentially the above-ground portion. Conventionally grown crops find support in the soil below them. Hydroponic systems require a substrate to support plant growth.
Kratky systems use a net pot, and you can suspend your plants in whatever substrate you like — such as clay pellets (hydroton), coco noir, or even rockwool. These ingredients can be found online and also at your local hydroponics or home improvement store.
Using these mediums has become commonplace because they are inert. In other words, they provide no nutrition and have a balanced pH. In addition, you can get creative with above-surface support with things such as bamboo, a tomato trellis, or even twine.
Water
You may be able to grow things without soil, but you can’t grow without water. While some gardeners prefer to use distilled water in their setup, plants often like less pure water, such as from the tap, because it already has mineral content.
If you use water from the faucet, be sure to let it sit out for a day so that any dissolved chlorine evaporates. Cities and municipalities use chlorine to help disinfect water systems, but that could stunt the growth of young plants.
What materials do I need?
You need just a few things to set up your Kratky system, and much of it can be reclaimed, borrowed, or reused. First, you’ll need a clean container or water reservoir — such as a mason jar, milk jug, plastic tote, or 5-gallon bucket.
Next, find a tool to cut holes in the top of your container, such as a power drill with a carbon hole saw or even an Exacto knife depending on container thickness. You can acquire tools by asking a neighbor, or some auto and home improvement stores allow cheap or free rentals of work tools. Please be careful when drilling holes or cutting.
Continuing, you need net pots to hold your plants, growing medium to support their roots, nutrients, and water. A pH meter and pH control kit could be helpful, but novice and amateur gardeners can get by just fine without them. Lastly, you can get a grow light, but this is unnecessary to start and will add to startup costs.
How do I set it up?
Step 1: Gather your materials.
Step 2: Cut or drill a hole in the lid of your reservoir just large enough to house the net pot.
Step 3: Fill the container with water, and use distilled or another form of safe-to-drink water.
Step 4: Dissolve nutrient solution into water per directions on bottle based on the volume of your container.
For example, if the directions are per gallon and your bucket holds 5 gallons, multiply the nutrients by five to have the correct ratio. Similarly, if you use a half-gallon milk jug, divide the exact instructions by two and maintain the right proportions of nutrients to the water. Remember it is better to have not enough nutrients versus too much, as the latter can cause nutrient burn. On the other hand, a nutrient deficit will slow plant growth.
Step 5: Adjust pH if desired. Hydroponic growers recommend a range of 5.8–6.5 for pH.
Step 6: Place the plant in a net pot with the desired substrate.
You can start seedlings in some substrates like rockwool, then place seedlings in the net pot. You can also take store-bought seedlings and gently wash off their roots with water — completely removing all soil.
Then, suspend your plant in a net pot with one hand at the correct height — keeping its roots positioned below the surface. Next, fill the area around the seedling with a substrate such as clay pellets (hydroton) until it is secured and upright. Do so carefully to avoid damaging your plant’s young roots.
Step 7: Lower net pot with plant down to secure within the container’s lid. Its roots should be suspended down from the net pot and slightly touching the nutrient-rich water below. Close lid tightly to block light and prevent rain from seeping.
Summary
Congratulations, you just learned how to make a cheap and easy hydroponic system! Hydroponics revolutionizes the way we grow food. No longer limited by growing seasons or lack of arable land, anyone can get started today growing food or flowers in their very own homemade Kratky system.
If you get creative, you can even keep your costs low. Despite what many perceive, hydroponics continues to stand the test of time and provide viable solutions to feeding some of the billions of humans on Earth.
By applying techniques developed by Dr. B.A. Kratky, you too can build your skills of growing in water. Whether off-grid or in areas lacking electricity, anyone can use this form of agriculture.
Several of the supplies can be found around the house or acquired for free, and this gives you a chance to experiment while barely touching your wallet. So try the Kratky Method and dabble in hydroponics today!
More Info:
About Dr. B.A. Kratky:
University of Hawai’i: https://bit.ly/3xzq4qL
ResearchGate: https://bit.ly/3u6LHMT
How does it work?
“Hydroponics: The power of water to grow food”: https://bit.ly/3nJBzrj
“How the Kratky Method of Hydroponics works”: https://bit.ly/3nFW3Ba
Where to find supplies:
Net Pots — 2 inches: https://bit.ly/2PxUCrE
Net Pots — 3 inches: https://bit.ly/3gPY4cG
Net Pots — 6 inches: https://bit.ly/3taFPkI
Nutrients — FoxFarm: https://bit.ly/3nymgkR
Nutrients — General Hydroponics Flora Series: https://bit.ly/3sZFBfT
How-Tos:
Trees.com: https://bit.ly/3vvxLfE
Kratky in Mason Jars: https://bit.ly/2R5XnB0
Kratky in Totes: https://bit.ly/3gV7ovT
Kratky in 5-gallon buckets: https://bit.ly/3nz48aB
