Hydroponics 101.2: The Kratky Method

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Hydroponics gives your students an opportunity for hands on, authentic learning that is novel, STEM related and gives them a chance to tinker. We’re currently exploring Hydroponics and Aquaponics in a blog series (read Hydroponics 101.1).

Choosing the container that you wish to use for your hydroponic system is crucial. There are two ways that you can approach this. You can either place your plant in a container that has no water and nutrient movement which is Kratky method) or you can re-circulate the water continuously using a pump and aerator. Which method you choose depends on your space and budget.

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With either method, you should begin your plants two to three weeks before transplanting them into your hydroponic system.

In the Kratky method you mix your nutrients in water and fill a container. Next, you prevent light from shining on the solution by duct taping or painting the container, then you cut a hole in the top of the container for your plant basket and you set the plant into the container with some of the roots not immersed in the liquid so they can get oxygen from the air. The upside is that you can grow lettuce and quick maturing plants in about 30 days. The downside is that the nutrient solution will run out or will begin to smell after about a month because no aeration of the solution takes place. This method is simple.

It is very important not to let light hit the solution or algae will begin to grow and use up all of the nutrients meant for your plant. This method is great for windowsill gardens or in small spaces that receive sunlight most of the day.

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I’ve noticed some differences with each method. First, root development is much greater in the circulation method and plants do grow a bit larger (see photo comparison). Secondly, the nutrient solution can be used for a longer period of time due to aeration. I have eaten my lettuce from both systems and both salads tasted very good.

Next week I will tackle a circulating system. But before then we’ll be posting on adding fish to our high school aquaponics system!

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