The Kratky Method: How to Setup a Passive Hydroponics System

Let’s face it: if you are going to build a hydroponics system from ground up, things can get pretty complicated from the get-go.

You’re not just talking about setting up pipes and a tub for the nutrient solution. We’re talking about an entire system here. And a system needs to work and also be able to balance itself as it performs the functions it was intended to do.

But not everyone is a curious engineer at heart. There are many folks who like the DIY route, but can only handle so much stress and technicalities when it comes to their hydroponics systems. This is where the Kratky Method comes in to lend a hand.

The Kratky Method was actually developed by Bernard A. Kratky from the University of Hawaii.

This particular method of hydroponics is highly recommended for those who wish to create an indoor hydroponics system that is passive, easy to setup and also easy to maintain.

What makes the Kratky method so unique?

– Unlike other existing systems, the Kratky Method is PASSIVE. What does this mean? You set it up once and just maintain it.

There are no motors or pumps to maintain, too. And this is probably one of the best things about the Kratky Method.

It is not your usual ebb and flow system that requires a separate vat for the nutrient solution.

– The Kratky Method does not require a large indoor space in order to work.

It requires only a fraction of the usual space and you won’t have to worry about setting up piping, drainage, electricals and other usual components in conventional hydroponics setups.

– This system is perfect for hydroponics growers who just want to test how soil-less gardening works in the first place.

If you don’t want to invest heavily in equipment and other hydroponics gear (plus sacks of growth medium) then this system is definitely for you.

Don’t worry – even without the usual equipment that other hydroponics growers use, you will still be able to grow the crops of your choice – guaranteed.

The Steps

The Kratky Method is exceedingly simple as a hydroponics system and you only need a few things to get started.

Here are the materials for your own Kratky passive hydroponics system:

– hydroponic raft

– plastic tank or plastic container with a lid

– crop seed of your choice

– water

– hydroponic nutrient solution

– net pot

– grow medium

1. Set up your plastic tank

Your plastic tank is the life of the Kratky passive hydroponics system. This is where all the action takes place as it will house both the net pot and the nutrient solution.

There are standard-sized hydroponic containers available on the market, but we highly recommend that you use food-grade plastic buckets for this project.

These buckets are marketed as “deep immersion” hydroponics containers online. In reality, they’re just your usual food-grade buckets with lids that are cut so you can put your net pot on top.

The container of your plastic container is very important. The lid of your bucket has to have an open space to fit the pot itself.

If your container’s lid doesn’t have this open space, you will have to measure the circumference of the net pot and cut one out accordingly.

Use a sharp knife to slowly create an opening for the net pot. Then test it out by putting the net pot in the opening.

The net pot has to fit in the opening up to its lid only. If it goes all the way through, then the opening has to be filled in a little so the net pot doesn’t fall through.

The net pot has to be snug in place so the net pot isn’t dunked into the nutrient solution.

Once you have the preliminaries set up, you’re now ready to proceed to the next step of the Krakty Method.

2. Set up your net pot

Once the primary setup has been completed, it’s time to prepare your crop.

We suggest that you first germinate your crop in a seedbed before transferring them to your main Kratky passive hydroponics system.

This is a best practice that is practiced even by commercial hydroponics growers. Seeds should be germinated first before being grown in the main system.

When your seeds have germinated sufficiently and are ready for transferring, it’s time to set up your net pot. Doing this is really easy.

All you have to do is to fill each net pot with your grow medium and voila – your net pot is ready to receive your germinated crop.

3. Combine your nutrient solution and fill your container

If you purchased a ready-made hydroponics nutrient solution mix, you simply have to match the ratio of the nutrient powder with water.

Be sure to know the exact measure of your container before mixing in the nutrients, so the water has the right ratio.

Adding too much nutrient mix to the solution can create a toxic solution (high salt, high pH, too) and adding too little is also problematic as your plant will not get the right amount of nutrients it needs.

Fill your plastic container all the way up near the brim, but be sure to leave just a little space for oxygen. Your net pot will essentially be riding on a raft on top of the nutrient solution.

4. Place the lid with the net pot on top and fix the lid.

After you’ve done this, you’re all done!

What should you expect in the coming weeks?

If all goes well, your Kratky passive hydroponics setup will begin its work in simply providing the nutrients necessary for plant growth.

You might be worried that the water level is going to choke your plant, right? Don’t worry about it all. Because as your plant grows, so does its roots (also called the root mat).

The roots will reach deep into the container to collect nutrients and moisture.

Through evaporation and absorption, your nutrient solution will slowly dissipate, creating a gap inside the container.

This gap is where the magic happens with your roots: the resulting gap from the dissipation of moisture will help create a space for oxygen exchange to take place between the plant’s immediate environment and its root mat.

As you may already know, roots need not just dissolved oxygen but also regular oxygen from the air.

And as long as there is constant moisture in the equation, the roots of your crops will not die out.

Common Questions About the Kratky Method

Q: Am I limited to just one net pot per container?

A: Definitely not. If you’re just starting out and have absolutely no idea how hydroponics works then you may want to start with just one net pot.

However, as you proceed to mastering the skills necessary for maintaining a passive hydroponics system, you can begin fanning out to grow more and more crops with this system.

A single plastic container can be fitted in such a way that it will be able to support three or more net pots at a time. However, and bear this in mind always – the more plants you are supporting in each container, the faster the dissipation of the moisture is going to be.

While the Kratky Method is a passive system, it is not a zero maintenance system.

Apart from measuring the pH level of the water daily, you have to replenish the nutrient solution when it begins to dip below what the root mats can reach.

Q: What is the ideal submersion point for the root mats?

A: There should definitely be space between the water level and the surface of the raft, but also make sure that all of your crops root mats are actually partially submerged in the water.

Sometimes, because of the levelling of the floor, you will notice that some plants are ideally submerged while others are not.

This is quite common and you shouldn’t fret over this. If the floor levelling is causing problems, then what you should do is to level the plastic container itself, so that the water from the far side would match the level on the left side of the plastic container.

Q: Are there any surprises waiting for me with this design?

A: Sometimes, nature finds its way to a hydroponics systems. We’re talking about bugs like crickets and even frogs!

Daily inspections are a must just to see if there are no bugs and frogs around your plants.

While frogs are helpful somewhat in quelling pests, they’re not part of the Kratky Method and they should definitely be removed (humanely, at that).

As for pests, you will be able to keep them out from your plants if you have a greenhouse (if you are keeping your plants outside). Though the Kratky Method was designed to create a passive hydroponics system for indoor use, yes, you can still put your growing pots outside if you want.