The Kratky Method – Complete Guide


Growing hydroponics is a productive way of growing plants for sure. However, for most of you, the method is complex and requires many types of equipment. This is especially a turnoff for beginners. But, what if I told you there is a simple and fun type of hydroponics system?

The good news is that there are many types of hydroponics systems available in the market to choose from. In fact, the level of innovation in the last few years is remarkable in this field. One of the recent types of hydroponic systems is the Kratky method. 

While hydroponic gardening mostly requires energy, a lot of space, pumps, and tubes, the Kratky method is a hands-off way of gardening without much complexity.

Sounds interesting, right? This article is a complete guide on how you can do gardening using the Kratky method hydroponics. Keep reading to take advantage of one of the most productive and easy ways of gardening.

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What Is the Kratky Method for Hydroponics?

The Kratky method is introduced by B.A Kratky who was studying at the University of Huawei. It is a type of deep-water culture but unlike the former, you do not need a pump. 

The Kratky method is famous for being a passive hydroponics system because you do not need air stones, electricity and many other things that are mandatory for other types of hydroponics methods. This makes the Kratky method an easy and cheap option.

You can say that the Kratky method is the one where you “set it and forget it” because once you set the system, you just let the plants do their own thing until they are ready to harvest. You don’t even have to make changes to the reservoir’s nutrients, which is almost a basic requirement for all other systems.

Kratky is an amazing low maintenance system that can set you free from the hustle and bustle involved in other systems. You have to place a seed in a raft for the Kratky system. Then, you place the raft in a tank filled with water and nutrients. One of the benefits you will get by opting for the Kratky method is that you will not have to adjust the nutrient solution multiple times.

As the roots grow, the water level keeps on dropping, which helps in creating a way for the air that the roots need. This makes sure you grow a healthy plant.

When your plant is ready for harvest, the nutrient water is all depleted. You just have to refill the tank with water and nutrient soil to use it again for gardening purposes. We recommend you clean the tank by spraying and vacuuming it after using it for 3 to 4 times.

What Do You Need?

To set up a Kratky method hydroponics system, you will need some tools. Here is a list of items that you will need.

Reservoir or a container

You will need these to grow your plants in so the size of the container or a reservoir depends on the size or number of your plants. If your plants are big and you want to have a big Kratky system, then you will need a large container or reservoir.

On the other hand, for smaller plants, you can even use milk jars.

Read our article on reservoirs to find the best hydroponic reservoir for you.


In case your container or reservoir does not come with a lid, you will need to purchase one. Plastic or Styrofoam lids are both available in the market, and both will work well for this system.

You need a lid to protect your plants from diseases, pests and the water from vaping. In addition to this, the lid supports your plant when it has grown above the water level.

Net Pots

To anchor the plants, you need net pots. Net pots are usually made from plastic mesh to help circulate air and promote drainage. Again, the size of your plants will determine the size of the net pots you will need.

Grow Medium

You will need growing mediums with the net pots. I prefer Hydroton ones because they are easy to use and have a neutral pH level.

A complete article on the best growing mediums is on the way!


You will need good quality nutrients to make sure the plants grow healthy. Hydroponic nutrients will do the job. We covered everything you need to know about nutrients in this article.

Measurement Tools

Some measurement tools like the pH meter will be of great help to you. With a good pH meter, you can check your Kratky system’s pH level frequently, which is also recommended.

pH meter

PH Control Kit

This kit helps in adjusting the pH level if the meter shows are to be higher or lower than the ideal level.

Steps to Follow

Setting up a Kratky system is a procedure that consists of six steps.

Step 1:

Fix the lid on the container or the reservoir. Then drill or cut the lid to create a hole so that you place the net pot in it. Create the size of the hole large enough to fit the net pot.

Step 2:

Fill the container with clean water. Both tap and distilled water will work. However, be careful not to fill the container with contaminated or unclean water.

Step 3:

Next, add the hydroponic nutrients to the container. Add them bottle by bottle, keeping into consideration the suggested amount on the packaging. Stir the mixture well so that all nutrients get dissolved.

Step 4:

Using the pH meter, check the pH level of the solution. If the pH meter shows numbers between 5.5 and 6.5, it is good enough. This shows the nutrient solution that you have prepared is perfect.

If the pH meter shows some numbers other than the suggested ones, you need to fix the pH solution before proceeding further. For this, follow the next step.

Step 5:

This is where you will use the pH kit to fix the pH levels of your solution. Remember, the suggested numbers of pH levels are between 5.5 and 6.5. So, adjust to bring the pH level between the suggested numbers.

You can add or remove the nutrient solution based on the readings until you get the desired reading.

Step 6:

In the drilled lid, place the net pot with growing media and your plant. Make sure that the roots of the plant are hanging freely in the air while the other parts are in the nutrient solution you have prepared.

How does the Kratky Method work?

So how does it all work for healthy plant growth? Let us explain a little here.

Oxygen, lighting, and moisture are mandatory for plants to grow. To grow at their full potential, plants also need micronutrients and macronutrients. This is where the Kratky method is an effective method because it supplies all these requirements in a simple way.

When the plant grows, they absorb the water. This water absorption creates and gives plants the air to breathe in. The “air gap” ensures the roots are exposed to air.

Fast-growing plants like cannabis grow best in the Kratky system because, by the time the water gets absorbed, the plant is fully grown and ready to harvest. If you want your plant to continue growing, you can simply add more water and nutrients to the system.

Kratky method - cannabis

Simple, isn’t it? However, like every other method, there are also challenges and drawbacks to this system as well.

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Challenges and Disadvantages of the Kratky Method

The Kratky method is known for being an affordable, easy and efficient way of gardening. However, there are some things worth considering before you choose to use this method.

Other Variables are Hard to Control

The truth is that the Kratky method is not completely a hands-off way of planting. Several other variables affect the Kratky method hydroponics.

You need to use clean water and correctly check the pH level of the nutrient solution before you place your plant to grow. The appropriate level of pH is crucial. Otherwise, you will need to check and adjust it frequently. This is why a good quality pH meter is mandatory.

However, this requires a lot of labor time. Even with the appropriate pH level in the initial stage, it is better if you occasionally check the pH level to ensure the optimum growth of the plant.

Moreover, the temperature is difficult to maintain at all times because water sits in place. The best way to avoid unstable temperature levels is to set the system in a place where there are no rapid changes in temperature. For example, an indoor room that is not much affected by the outdoor temperature.

Installing a ventilation system, especially in summers, is always a good idea. Additionally, the use of shade clothes is also effective.

Only Suitable for Small Plant Set-Up

One of the limitations of the Kratky method is that it is only best for smaller plants. This system is best for leafy green plants, for instance, cannabis, spinach, and growing lettuce. 

However, the method is extremely ineffective for fruits like cucumbers, tomatoes, or any other plants that require large space.

Larger Systems Cannot Be Built

Kratky systems are only useful if you are doing a small scale gardening. If you want to produce on a larger scale, this method is not efficient. One of the reasons is that large Kratky systems are time-consuming.

Imagine cleaning 100 tanks, it will require a lot of effort and labor. This is why we recommend it for small scale use.

The Risk of Pest

In the Kratky method, because you are not using an air stone, the nutrient solution will be still. It is a passive system, which means it attracts pests, especially mosquitoes and grasshoppers. Make sure you protect your reservoir from pests while allowing air to pass through.

Kratky Method - pests

Water Quality Issues:

As you will not replace the water in the Kratky method, the water quality you are initially using must meet high standards. Keep the PPM low to avoid concentration of salt.

Also, keep your plants protected from heavy rainfall. If you have set the system outdoors, you will have to shift it to protect from rainwater. Otherwise, the level of water will increase, and your plant will drown. Even strong winds will harm your plants. So you will need to take care of your plants in such weather.

What Types of Plants Can You Grow with the Kratky Hydroponic Method?

The types of plants that are best grown using Kratky hydroponics methods are the leafy green plants. These plants grow at a faster speed as compared to other plants. Examples of such plants are cannabis, herbs, heads of lettuce, and spinach.

Growing large plants like pepper are also possible. However, you will need a large container for that. Additionally, you will have to keep a regular check on the water and the nutrient level to make sure your plant gets optimum growth. The roots of the plants should have sufficient access to oxygen and water.

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Both the pros and cons of going for the Kratky systems allow you to make a better decision. In the end, your goals determine whether this system will work best for you or not.

If you are a beginner in hydroponics, then you should give the Kratky system a try. Moreover, if you are not looking forward to growing plants in large quantities, then this method is a good one too. However, if you want to produce in larger quantities, this is not a recommended method.

The Kratky method, without a doubt, is a fairly easy and productive method of growing plants. The items needed and the total set up process is not complex, unlike other hydroponic systems.

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