The Kratky Method: How To Grow Food Almost Automatically
Although I already think that hydroponics is one of the most interesting, simple, and productive gardening methods out there, what continues to surprise me is the amount of innovation that happens in the field. There are so many different hydroponic systems out there and they seem to be limited only by our imagination.
Not too long ago I was looking for more ways to experiment with my deep water culture systems, including building a very simple hydroponics for kids project. I wanted to keep the system as simple as possible while making sure it still produced a healthy plant.
Enter the Kratky Method.
What Is The Kratky Method?
Let's start off with my video overview of the Kratky Method:
Because hydroponics grows plants without soil, there are often a lot of moving parts in a hydroponic system: pumps, wicks, airstones…and the electricity to power them all. Don’t get me wrong – this is part of what I LOVE about hydroponics – but sometimes you just want to keep it simple.
This is where the Kratky method shines. It’s a technique that allows you to grow hydroponically without electricity, pumps, or wicks of any kind. In fact, you don’t even have to change your reservoir or add nutrients. It’s as close to a completely “hands off” growing technique as I’ve ever seen.
How to Build a Kratky System
This is a really fun method to mess around with – give it a shot! Once you understand the basic principles, it’s probably the easiest and cheapest method you could ever use to grow hydroponically.
Here's everything you need to get started with the Kratky method:
5 Gallon Bucket
3" Net Pots
3" Hole Bit
ph Control Kit
How The Kratky Method Works In Detail
In a traditional deep water culture setup, you typically have your plant in a net pot with growing medium and you place it in a reservoir. Then you fill the reservoir with nutrient solution up to a certain point, making sure it doesn’t touch the net pot.
The airstone that you add to your system will create bubbles that pop at the surface of the water, hitting your growing media and feeding your plant’s young root system. As the roots grow, they’ll eventually hit the surface of the water and growth will explode from there on out.
With the Kratky Method, you actually fill your reservoir with properly conditioned water further, making sure to cover the bottom third of the net pot with water. The reason? Without an airstone, your plants will need water at the start of their lives, and this technique ensures they’ll never dry out as your growing media is constantly wet.
As the plant continues to grow, it will use water and the water level will decline – but your plant’s roots will have descended into the nutrient solution by that time.
You might be wondering, “Aren’t airstones used for more than just wetting the growing media in the seedling phase?” You’re right – this is where the beauty of the Kratky Method starts to shine. Because you are not refilling your reservoir, your plants will keep using up water and exposing more and more of their root systems to the air, which will ensure your plants get enough oxygen to survive and thrive.
Potential Problems With The Kratky Method
Like any system, there are some flaws and considerations you should be aware of if you want to make sure you have a successful grow.
Good for Leafy Greens Only - This is designed to be a simple, hands-off method. That means it can’t really account for the increased nutrient and water requirements of plants that bear fruit. Use this for leafy greens like lettuce, spinach, etc – not fruiting plants like tomatoes, cucumbers, etc.
Pests – Because your nutrient solution will be still (because you’re not using an airstone), it can draw the attention of pests, namely mosquitoes. To avoid this, make sure that the reservoir is protected from any type of bug or pest, while allowing some oxygen and air to flow in as well.
Water Quality – You are not going to be replacing or adjusting the water level in your reservoir, so it’s important to start with very high quality water. If you’re going with the Kratky Method, I would recommend reverse osmosis or filtered water – get your PPM as low as possible so you avoid a dangerous concentration of salts.
Watch Your pH – If you’re new to the method, you may want to pick up a pH pen and test it every day. Once you get the hang of how to prepare your nutrient reservoir for the plant that you’re growing, you can leave the system to do its job!
*You can find the original paper about the Kratky method here. Be forewarned, it gets a little technical!