Hydroponics and Aquaponics

Kratky hydroponic method of growing vegetables

What is the Kratky System and what grows best in the Kratky hydroponic method of growing vegetables?

Kratky method of growing vegetables Kratky method

The Kratky system, also known as the non-circulating system, is one of the easiest of the hydroponic systems.

If you ever put a cutting from a plant in a glass of water until it grows roots, then you have seen the basics.

Kratky method of growing vegetables Basil in a glass

So how did the glass in the windowsill become the Kratky method of growing vegetables?

Dr. Kratky from the University of Hawaii figured out a way to keep plants growing healthy far beyond root starting.

A plant can and will die if they stay submerged in water. The will actually drown without air. Plant roots need air to be healthy. The Kratky method allows air to the roots keeping them from drowning.

If you leave a plant submerged in water too long the plant’s roots will rot and the plant will die. When you put a cutting in bottle of water it will grow roots. However if you don’t change the water regularly the roots will turn brown. This is because the roots have taken much of the air out of the water. The roots are drowning and will die. You can solve this issue by changing the water often or you can use the Kratky method of growing.

Dr. Kratky’s method of keeping an air pocket will prevent the roots from rotting.

What is the Kratky hydroponic method of growing vegetables?

The Kratky method solves this problem WITHOUT air stones or pumps. It is perfect for an off-grid, no electricity situation. See his university of Hawaii study here

In Dr. Kratky’s method, a plant is stationary above the water line on a board or piece of insulation. The plant is held with some roots submerged and some roots held above the waterline. The stationary board keeps the warm moist air around the roots that are not submerged allowing them to breathe without drying out. Adding an air stone can be a good idea but it is not necessary.

The water solution is filled only when you first put your plant in the system. As the plants grow the air pocket increases and the water decreases.

If all is done well, the water will run out just as the plants are ready to harvest!

This can truly be a set it up and forget it situation.

Kratky method of growing vegetables Hydroponic growing stages

What vegetables grow best in the Kratky method?

These systems are really great for lettuces and greens.

  • All Lettuce
  • Kale
  • Spinach
  • Bok Chou
  • Chard
  • Collard greens
  • Arugula
  • Endive

Some herbs will do well.

  • Basil
  • Mint
  • Dill
  • Cilantro
  • Sage
  • Thyme

What vegetables don’t do well with the Kratky hydroponic method?

Vegetables that are heavy feeders don’t do well in a Kratky hydroponic system.

The best part of the Kratky hydroponic method is that you fill it once then the plants have enough to grow through the natural cycle of life.

Since in this method you can not always see and test the water solution, it will be too hard to control the right amount of nutrients.

Things I have not had success with using this method

  • Broccoli
  • Brussel sprouts
  • Peppers
  • Tomatoes

Herbs that don’t work well in this system

  • Rosemary
  • Aloe Vera
  • St. John’s wart
  • Chives
  • Lavender

How to grow herbs with Kratky hydroponic method

The Kratky hydroponic method is designed for use from start to finish of the plant’s life with one fill of water and nutrients. However, I have had a lot of success with herbs that prefer moisture. For example, basil does well but rosemary prefers drier soil and doesn’t do well in this system.

Air purifier with planter

Herbs in this system will do well only if you keep an eye on the water level. Keep the level of water at a level that will keep about half the length of the roots underwater and half in the air.

Krstky hydroponic method to grow vegetables Grow table

An important thing to remember is:

Keep an eye on the temperature!!

The number one reason I have seen plant struggle is the water gets cold. The temp should be in the 72-76 degree F. Cold water will cause the growth the slow or even stop. This is easily remedied by heating the water back up.

Put a fish tank heater in your water solution to regulate the temperature without any work. Fish tanks are typically heated to the mid 70s so it works perfect in these systems.

Keep an eye on the PH.

The easy and cheap way to test is with fish tank test strips. There are lots of ways to deal with high or low PH. Not a concern in single plant bottles. In a bigger system, you should check the PH every month or so.

Don’t forget proper lighting!

Regardless of how you grow your plants, proper lighting is always a must.

Check out. Making sense of grow lights for more on the subject of lighting.

The best reasons to try the Kratky hydroponic method of growing vegetables

The Kratky hydroponic method of growing vegetables is a great way to begin your hydroponic indoor farm.

  • It is super easy to start
  • Almost no work to grow vegetables
  • Total off-grid, no power is needed
  • Can be small enough to fit in any space

Try some of the other methods of growing with hydroponics like NFT and Dutch buckets

please check out my book on Amazon!

Please let me know what you think in the comments

Thanks, Dorothy

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