The Short Guide to Using Soil in the Kratky Method: Everything You Need to Know

There are several different mediums you can start a hydroponic plant in such as rockwool, coco coir and peat, but if you only have soil, can you use it to grow plants in the kratky method? Although it is generally recognized that soil can work as a plant medium in kratky hydroponics, there are important factors that may make you want to choose a different media. I’ll tell you about my most important considerations below, but first

# What is the Kratky method?

The Kratky method is a popular hydroponic technique that allows plants to grow without the need for electricity, pumps, or a continuous water supply. This passive hydroponic method was developed by Dr. Bernard Kratky at the University of Hawaii in the 1990s. It is a simple and low-cost system that is ideal for beginners and those with limited space.

Kratky Cilantro Growing without Soil

In the Kratky method, plants are grown in containers filled with a nutrient solution. Unlike traditional hydroponics, the nutrient solution is not recirculated or aerated. Instead, the plants rely on a passive system where the solution level gradually decreases as the plants consume water and nutrients. This creates an air gap between the solution and the roots, allowing the plants to take in oxygen from the air.

Understanding the role of soil in the Kratky method

While the Kratky method is often associated with soilless growing, using soil can offer several advantages. A net cup full of soil can play a crucial role in the Kratky method by providing physical support, moisture retention, and a reservoir of nutrients. It can also help to stabilize pH levels and buffer against rapid changes in the nutrient solution.

When using soil in the Kratky method, it is important to choose a well-draining soil mix that does not compact easily. A loose and airy soil will allow for better root growth and prevent waterlogging. Additionally, the soil should be free from pests, diseases, and weed seeds to ensure healthy plant growth. The best way to make sure that the soil is suitable is to use an inert potting soil for young seedlings.

Benefits of using soil in the Kratky method

Using soil in the Kratky method offers several benefits. Firstly, soil provides a stable medium for plants to anchor their roots. This is especially important for larger plants that require additional support. Secondly, soil has the ability to retain moisture, reducing the frequency of watering in the Kratky system. This can be advantageous for those who have limited time or are prone to forgetting to water their plants.

Soil also acts as a reservoir of nutrients, slowly releasing them to the plant roots as needed. This can help to maintain a more balanced nutrient supply and prevent nutrient deficiencies or toxicities. Furthermore, soil can help to stabilize the pH levels in the nutrient solution, reducing the risk of drastic pH fluctuations that can harm plant growth.

Soil considerations for the Kratky method

When using soil in the Kratky method, it is important to consider the specific needs of your plants. Different plants have different soil requirements, so it is essential to choose a soil mix that is suitable for the types of plants you are growing. Some plants prefer a more acidic soil, while others thrive in a more alkaline environment.

Clean Soil for use in Hydroponics

Choosing the right soil for your Kratky system

When choosing soil for your Kratky system, it is important to select a high-quality potting mix that is suitable for container gardening. Look for a mix that is well-draining, lightweight, and free from weed seeds. Avoid using garden soil, as it can be heavy and may not provide adequate drainage.

Preparing the soil for the Kratky method

Before planting in soil for the Kratky method, it is important to properly prepare the soil to ensure optimal growing conditions. Start by moistening the soil mix until it’s quite damp but not soggy. Too much moisture can lead to waterlogging, while too little moisture can cause the roots to dry out.

Once the soil is prepared, fill the containers with the soil mix, leaving enough room for the plants to grow. Gently firm the soil around the roots to provide stability and ensure good root-to-soil contact.

Planting in soil for the Kratky method

When planting in soil for the Kratky method, it is important to make sure that the pots and soil are in contact with the reservoir of nutrients and that the plant can wick up the food it will need soon. Start by selecting healthy seedlings or transplants that are free from pests and diseases. Make sure to space the plants adequately to allow for proper air circulation and prevent overcrowding.

Dig a hole in the soil mix that is large enough to accommodate the roots of the plant. Place the plant in the hole and gently backfill with soil, making sure to cover the roots completely. Press the soil lightly around the base of the plant to secure it in place.

After planting, water the soil thoroughly to ensure that it is evenly moist. Avoid overwatering, as this can lead to waterlogging and root rot. Monitor the moisture levels in the soil regularly and adjust the watering as needed.

Once you’ve watered the plant quite a bit and all of the loose soil has come out, you can put it on the reservoir for longer term growth.

Maintaining soil in the Kratky method

To maintain soil in the Kratky method, there shouldn’t be very much required. As long as the plant continues to grow into the reservoir and fill the soil with roots for stability and oxygen, there should be no issues to maintain.

Troubleshooting common soil-related issues in the Kratky method

While using soil in the Kratky method offers many benefits, there can be challenges along the way. One common issue is high organic matter soil contaminating the nutrient rich water, leading to bacterial growth.

If the soil has live organisms that cause the water to grow bacteria or algae, then the water will need to be changed and monitored more often.

Pests and diseases can also affect plants grown in soil. Monitor your plants regularly for any signs of infestation or disease. If pests or diseases are detected, take appropriate measures to control them, such as using organic pest control methods or applying fungicides.

Algae Issue in Kratky Reservoir


Using soil in the Kratky method can offer several advantages, including physical support, moisture retention, and a reservoir of nutrients. By understanding the role of soil and considering the specific needs of your plants, you can successfully incorporate soil into your Kratky system. Remember to choose a high-quality soil mix, properly prepare the soil, and provide adequate maintenance to ensure optimal plant growth. While the Kratky method is often associated with soilless growing, using soil can be a viable option for those looking for a more traditional approach to hydroponics. However, it is important to note that there are more suitable inert media available for the Kratky method, and I’d recommend most common solutions like rockwool, collars, or coir rather than soil.

The only way to see what’s right for your garden is to experiment. Try one or several types of media for your hydroponic garden and see which one works best for you. Happy Hydro growing!


Located in Portland, Oregon, Tim started gardening in his 20's and after a couple of decades felt like he had some things to share.

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