What Can You Grow with the Kratky Method? All This!

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A basket pf hydroponically-grown lettuce plants.

The Kratky method of hydroponic growing is awesome for several reasons: It’s perfect for beginners, requires no electricity and is a simple set-up for passive growing.

That all sounds great, but what can you grow with the Kratky method? These crops are your best bet for a successful, rapid harvest: 

  • Leafy greens
  • Lettuce
  • Some herbs

Admittedly, these categories are pretty general. 

So let’s break them down a bit to give you a better idea of what you can grow using a simple Kratky set-up.

What Can You Grow With the Kratky Method?

I spent quite a bit of time scouring the internet to compile this comprehensive overview of the best plants for the Kratky method. 

Of course, individual growing conditions will affect the final outcome. But in general, these crops will grow best and with the least effort on your part:

Leafy Greens

Leafy greens are some of the most nutrient-dense foods out there, and they’re perfectly suited to thrive in a Kratky tank. 

  • Spinach
  • Chard
  • Kale
  • Bok Choi
  • Escarole
  • Radicchio
  • Mesclun
  • Mustard greens
  • Arugula
  • Rapini
  • Collard greens
  • Tatsoi
  • Endive
  • Fennel
  • Watercress

Lettuce

Lettuce is one of the most popular crops for any hydroponic growing method.

All varieties of lettuce grow well using the Kratky method, and there’s plenty of options to choose from! 

  • Romaine
  • Tom Thumb
  • Boston (also known as bibb)
  • Looseleaf
  • Little Ceasar
  • Crisphead
  • Butterhead
  • Coral
  • Ruby 
  • Oakleaf
  • Grand Rapids
  • Dynamite
  • Iceberg
  • Paris White
  • Parris Island

Some Herbs

Herbs that reach maturity quickly and tolerate damp roots are the ideal choices here. 

Plus, a Kratky set-up is simple to replicate, so you can start a new crop every few weeks for a continual harvest of fresh herbs!

  • Italian (sweet) basil
  • Thai basil
  • Lemon basil
  • Mint
  • Dill
  • Sage
  • Garlic chives
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Why Do These Plants Thrive with the Kratky Method?

There are three main factors that make all these plants good choices for Kratky hydroponic set-ups:

  1. Fast growth rate
  2. Small size
  3. They are leaf crops (they do not produce fruit)

Why does that make a difference? It all comes down to how the Kratky method operates. 

At the beginning of the growing process:

A newly set up Kratky method hydroponics tank with the seedling roots just below the water level.

After a few weeks of growth:

An older Kratky hydroponics tank, with mature plant roots and low water level.

As the illustrations above show, the Kratky method uses a passive system to keep your plant’s root tips just below the water’s surface.

Ideally, root growth should roughly equal the decreasing water level.

Plants that mature quickly, stay fairly small in size and yield only leaves find a perfect home in these conditions. 

If you’re interested in learning exactly how the Kratky system works, you can check out the original research paper. But be aware that it’s pretty technical!

RELATED: Have more questions about hydroponic growing beyond the Kratky method? Visit our post laying out the differences between hydroponics and aquaponics to get a high-level overview!

Let’s look at each point in a bit more detail:

Fast Growth Rate

For maximum convenience and production from a Kratky set-up, your plant should be able to complete a full life cycle before needing a water or nutrient refill. 

As opposed to other hydroponic systems that can run almost indefinitely, the Kratky method doesn’t use air pumps or any water-circulating devices.

The result? Your run time is fairly short-lived. 

Fast-growing plants overcome the limitations of the Kratky method to produce their harvest before your tank runs out of water/nutrients or becomes a harbor for bacteria or fungal growth.

Most of the plants listed above should be harvestable 6 weeks after planting or before

The tallest, thickest, strongest grow tents in the industry are the Gorilla Grow Tents.

Small Size

Kratky hydroponic set-ups work best when they’re kept small and manageable. Once you scale up past a certain point, the system becomes inefficient and more work than it’s worth. 

With small plants, the growth rate is roughly equal to what your water/nutrient tank can support. 

On the other hand, larger plants have proportionately larger root systems, and a Kratky tank will probably not be enough to accommodate their needs.

In all likelihood, you’ll run into problems with:

  • Stunted growth
  • Poor yield
  • Frequent water/nutrient refills
  • Your growing tank becoming too top-heavy

Compact plants let you enjoy the ease and simplicity of the Kratky method to the fullest.

Exclusive Leaf Crops

Each of the plants listed above is a leaf crop, meaning that it produces only edible foliage, no fruits or vegetables. 

(If left to their own devices, however, many of these plants would eventually start producing flowers and seeds.)

It takes a lot of nutrients, water and energy for a plant to produce fruits or vegetables!

That’s why you have to amend your soil with compost or other fertilizers to get the best yields in your garden or orchard. 

Hydroponic growing is no different, and plants that produce flowers and then fruit need a constant flow of fresh nutrients to thrive. 

Due to its simple structure, it’s very difficult to meet these demands with the Kratky technique. 

But it’s perfect for those delicious and nutritious leaf crops! 

If you’re interested in building your own Kratky method hydroponics tank, check out this helpful video from Hoocho:

Which Crops Don’t Grow Well With the Kratky Method?

It’s not impossible to raise a slower-growing or larger crop using the Kratky technique.

But you’ll have to invest more time and effort to keep your water at the proper level, ensure nutrients are available and prevent microorganism overgrowth. 

In other words, you’ll lose a lot of the wonderful convenience and passive growing that makes the Kratky method so awesome. 

Here’s a list of plants that aren’t very Kratky-friendly without at least some extra work:

Root Crops

  • Carrots
  • Potatoes
  • Turnips
  • Beets
  • Sweet potatoes
  • Parsnips

Efficiency is really the issue here. The Kratky method just doesn’t allow you enough surface area to produce a worthwhile harvest.

Plants That Take a Long Time to Mature

  • Lavender
  • Brussels sprouts
  • Peppers
  • Corn
  • Beans
  • Strawberries

You’re looking at lots of potential water changes and nutrient refills here before your plants reach maturity. 

Large, Fruit-Producing Plants

  • Tomatoes
  • Eggplants
  • Zucchini
  • Pumpkins 
  • Squash
  • Cucumber
  • Melons

As we mentioned before, fruiting plants are usually heavy feeders, so the nutrients in a Kratky system can rapidly become depleted. 

Also, tall or sprawling plants can quickly overwhelm your growing area. 

Frequently Asked Questions about Growing with the Kratky Method

Just like any other technique of hydroponic growing, the Kratky method requires these essential nutrients:

  • Nitrogen
  • Phosphorous
  • Potassium 
  • Calcium
  • Magnesium

You could buy each nutrient separately and mix up your own solution.

But buying commercial hydroponic nutrient blends is far simpler and produces more reliable results. This 2-part blend from 5 Gallon Bucket Hydro could be a great choice. 

Fill your Krakty tank almost completely, so the water submerges the growing cup by about 1/2 inch or so.

The actual water volume you need will vary depending on your tank. 

Dr. Bernard A. Kratky, a Researcher Emeritus at the University of Hawaii, discovered the non-circulating hydroponic culture technique that bears his name in 2004. 

Final Thoughts

The Kratky method of hydroponics has many benefits to offer, especially if you want to grow some fresh produce in a small area or forgo electricity altogether.

When you choose the ideal crops, it’s almost a set-it-and-forget-it growing strategy.

And with the phenomenal selection of leafy greens, lettuce and suitable herbs to choose from, it’ll be a while before you run out of options!

We want to hear from you! Have you tried the Kratky method? What did you grow?

Let us know in the comments! 

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