DIY Kratky Hydroponic System: Grow Your Greens For Less

Kratky systems are ideal for DIY enthusiasts looking to grow leafy greens and vegetables in a cost-effective, low-maintenance way. 

Known for its simplicity and efficiency, it is the perfect setup to put leafy greens on your table for less.

Here, I will take you through the steps of setting up your first Kratky setup from start to finish.

If you are on a budget, consider setting up a Kratky system and a couple of trays with Microgreens. Trust me, you will be harvesting plenty of greens in no time. 

But what is so unique about the Kratky method?

What is a Kratky Hydroponic System?

Think of the Kratky method as the crockpot of indoor gardening – get your ingredients in place, set it, forget it, and watch your plants grow.

The genius of the Kratky method is that it is a passive system where time works for us. Let me explain what I mean. 

In the simplest terms, plants need light, air, water, nutrients and space to grow.

But the needs are not the same at all parts of the plant’s life cycle. And this is where the Kratkly system shines.

Kratky system week 1 with seeds planted in net pots
Seeds planted on top of moist LECA

Our seeds do not need any extra nutrition to germinate and sprout. But as the seeds grow into seedlings, the root system reaches the reservoir with nutrient solution.

As the plants absorb the water and nutrients they need, an air pocket is created inside the reservoir. Can you see where we are going? 

The root system is now exposed to nutrients and moist air inside the reservoir.

Kratky system week 2 showing how time creates an air pocket inside the reservoir to aerate the roots
An air pocket is created to aerate the root system

This pocket of moist air aerates the roots without requiring any pumps.

Traditional active hydroponic systems use pumps to aerate and circulate the nutrients in the reservoir. These active types of systems include Deep Water Culture (DWC), Grow Buckets, and Ebb and Flow Grow Beds. 

Dr. B.A. Kratky [1] developed the method, which is truly beautiful in all its simplicity. There is no need for electricity or pumps – just simple and efficient indoor gardening.

Building Your Kratky System: A Step-by-Step Guide

1. Gather your supplies

Any successful DIY gardening project starts with prep work. Luckily, the Kratky method uses only a few moving parts.

A standard jug as reservoir: Think milk jug size or similar. This one-liter jug will sustain one basil plant.

You can us a standard jug for Kratky hydroponics
In this guide, I use a standard water jug.
I am using a translucent jug in this tutorial for presentation purposes. Translucent containers should be covered to prevent algae growth.

Growing medium: LECA (Lightweight Expanded Clay Aggregate), Rockwool, pool noodles or similar. Soak the LECA in water for a couple of hours, preferably overnight. You want the LECA to be fully hydrated. Also, I am a stickler for food-safe materials but use your discretion. 

Soaking the LECA to hydrate it before use
Soaking my LECA before use

Seed starter plugs (optional): It is easier to start seeds in plugs, but you can also place seeds directly on moist LECA.

Seed-starter plugs are optional but convenient.
Seed-starter plugs (optional)

Hydroponic fertilizer: I prefer using a 3-part hydroponic fertilizer.

3-part hydroponic fertilizer
3-part hydroponic fertilizer

Net pots: I find the 3-inch/7.62 cm size ideal for growing hydroponic leafy greens, but adjust the size to fit your jug or reservoir. 

3-inch net pot
3-inch net pot

Full spectrum grow light: A sunny window sill can work if you have at least 8 hours of natural sunlight.

Full-spectrum grow light
Full-spectrum grow light

Your choice of seeds: I recommend starting with something easy like lettuce or sweet basil.

Genovese basil seeds
Genovese basil seeds

2. Prepping the jug

Clean the jug thoroughly. Make sure the hole is just big enough to hold the net pot.

3. Filling the jug with water

Fill the jug with water. I use regular tap water. You want the water level to reach the top third of the net pot when it is filed with LECA. Test. It is hard to get it right without testing.

Filling the jug with water
Filling jug with water

4. Adding the hydroponic nutrients

Follow the dosage instructions for your chosen hydroponic fertilizer. More is not better; if anything, give a bit less than indicated. 

I use a 3-part hydroponic fertilizer and add 0,5 ml per liter of water. Try to be precise. Overdosing can lead to toxicity, and your plants will die.

If you use a multi-part hydroponic fertilizer, add each part to the water separately. 

Adding hydroponic fertilizer
Adding hydroponic fertilizer
I have had great success giving half the recommended dosage when I grow leafy greens and herbs hydroponically. But never give less when growing flowering and fruiting plants. 

5. Setting up the growing medium

By now, your LECA should be fully hydrated. 

Here, you have two options:

  • With seed starter plugs: Fill the net pot with LECA, leaving room for the plugs.
Allow room for the seed starter plug when adding LECA to the net pot
Allow room for the seed starter plug when adding LECA
  • LECA only: Fill your net pots with the hydrated LECA.
Fill net pot with soaked LECA
Fill the net pot with LECA

6. Planting the seeds

Plant 3-5 seeds in each starter plug; alternatively, scatter about 10 seeds on the moist LECA pellets. Try spacing the seeds evenly. Planting more seeds gives us a better chance of a healthy yield. 

Finish this step by covering the net pots with plastic to trap moisture and create a mini-greenhouse effect. Remember to remove the plastic when you see the first leaves sprouting.

Plant 3-5 seeds per seed starter plug
Plant 3-5 seeds per plug
Starter plugs are convenient but optional. I use them as it gives me control of placement. I can place up to 3 smaller plugs in a net pot when I use a one gallon container.

7. Give your Kratky Hydroponic System plenty of light

A sunny window sill may work if you have at least 8 hours of natural sunlight. Yes, sunlight – not daylight.

I garden in zone 7 and use hydroponic systems when the seasons turn dark and sunlight is scarce. For me, a full spectrum grow light is a must.

And thankfully, nowadays, you can buy full-spectrum hydroponic grow bulbs for the price of a large cup of coffee at Starbucks. Full-blown lights are available for about 25-30 dollars and up.

I have said it before, but full-spectrum hydroponic grow lights will revolutionize your yield and approach to indoor gardening. 

And there you have it; your system is up and running. There is no need to top up the reservoir; the system will run independently for one complete growth cycle.

Cover the jug with paper or a cloth if you are using a translucent container.
Cover if using a translucent container
Cover if the container is translucent.

Pros and Cons of the Kratky System

The Kratky method is genius. Still, you would see a Kratky system in a commercial setup.

So, let’s look at some of the benefits and limitations of the Kratlky setup.

Pros of the Kratky system

We have already touched upon many of the benefits of the Kratky method, but here is a summary:

  • Low Maintenance: No moving parts or ongoing maintenance means less fuss and no work.
  • Cost-Effective: No need to buy pumps or expensive equipment. Use a milk jug and a window sill – or an existing lamp with an LED bulb.
  • Beginner-Friendly: An ideal setup for beginners looking to learn more about hydroponics.
  • Quiet Operation: No pumps mean no noise.
  • High Yielding: Efficient nutrient use leads to robust plant growth and healthy yield for minimum effort. 
Kratky setup
A simple Kratky setup

Cons of the Kratky system

All systems have limitations, and no one setup is perfect. And even though the Kratky method is excellent, there are a couple of noteworthy limitations to be aware of.,

  • Poor Scalability: Kratky is great for small-scale indoor gardening but is not practical if you want to grow enough for your whole family. Setup is cheap, but the setup cost remains the same for each new unit. 
 I use air pumps for my grow buckets. This means I need to buy a pump to build my first bucket. But that pump will then be used to run 10-20 buckets and it is easy and inexpensive to scale and expand my indoor setup.
  • Not suited for all plants: Kratky is best suited for leafy greens and herbs. You can grow hydroponic tomatoes and peppers, but your results will vary, and maintaining a healthy pH and EC level will be challenging.
  • Visual appeal: Compared to a hydroponic kit, Kratky setups are usually not nice-looking and do not belong in plain sight on a kitchen counter. (OK, I don’t necessarily agree, but this is the reality in my home.)

Frequently Asked Questions

Do I need a grow light?

Yes, unless you can provide at least 8 hours of natural sunlight daily. Plants need sunlight; a full-spectrum grow light is like a sun substitute for indoor gardeners.

Why shouldn’t the container be transparent?

Combining light, nutrients, and a transparent container will lead to algae buildup. You want to avoid algae as it will compete with your plants for nutrients and resources.

Conclusion And Key Takeaways

  • Kratky method: A simple, low-maintenance passive hydroponic system.
  • DIY friendly: Easy to set up with household items.
  • Hydroponic fertilizer: You must feed your plants for a healthy yield.
  • Growing medium: Soak the LECA; seed starter plugs are optional. 
  • Light is crucial: Ensure a minimum of 8 hours of daily sunlight or use grow lights.
  • Leafy greens and herbs: DIY Kratky systems best suit herbs and leafy veggies.

Helpful sources:


Mattias Magnusson: Hello, I'm Mattias, a passionate and experienced gardening enthusiast. I am the creator of, your guide to year-round herb and veggie growing. Let's simplify green living, no matter your space or location.