Off Grid Hydroponics -
No Electricity Required

By Dorothy Chapman

Hydroponics can be an effective way to grow food for your family.  But can you grow food with hydroponics without electricity?  Yes!  Off grid hydroponic is easy and can be done in almost any space, indoors or outside.

Grow vegetables hydroponically.

What is hydroponics?

Hydroponics is a method of growing plants without using soil.  With hydroponics, you grow plants in a nutrient and water solution, not soil.

Why use hydroponics?

Bigger Plants!

Studies have shown that plants will grow up to 35% bigger when grown using hydroponics instead of traditional soil methods. Why? Because water and nutrient solutions used in hydroponics are a  much more effective way of getting your plants the nutrients they need to grow. 

Less Disease

There is also much less disease when growing with hydroponics.  Many of the diseases that can inhibit growing are related to soil.  Root rot, leaf spots, and fruit rot are all caused by fungus, bacteria, and other organisms that live in the soil.  These problems are virtually eliminated with the use of hydroponics.

Healthy plants

When your plants need more nutrients you just add them to your  solution.  If they need different nutrients to optimize growing you can easily adjust the nutrients in the water.  This will give the plants exactly what they need in a quick and efficient way.

Roots soaking up liquid nutrients.

Types of Hydroponic systems

There are three basic hydroponic systems widely used in farming vegetables:

  1. NFT or nutrient film solution,
  2. Dutch buckets, and
  3. DWC or deep water culture.

These all have their best uses and are all effective ways of growing vegetables, however they all use electricity to pump the water through the systems.  

For off grid hydroponic growing we need to look at a sub category of deep water culture called the Kratky method of hydroponics.

The Kratky Method

Dr. Kratky of the University of Hawaii perfected a method of growing using hydroponic principles but without the need for electricity.

This system is the best and easiest way to grow endless greens of all kinds.  However, this is not a great system to grow large vegetables.

The Kratky method is a non-circulating system, meaning that the nutrient rich water does not move thru the system.  This makes it perfect of off grid or no power situations.

How it works:

•    Fill the water solution to the top of a container.
•    As the plant begins to grow, the roots reach into the solution.
•    The plant drinks, causing an air pocket to form.
•    The bigger the root system gets, the bigger the air pocket gets. 
•    When the water is gone the plants will be ready to harvest.

The air pocket is the key.

Deep water systems need to have an air stone to keep oxygen in the roots.  This is because in a deep root system you continually add water to the system keeping the roots completely submerged.  Without an air stone the roots will rot and the plant will die.

Air Stone for the roots.

If you try the Kratky method make sure you let that air pocket increase naturally. 

Don’t add more water!

This is a good thing to keep in mind if you are growing herbs on the window sill in bottles.  Keep an air pocket so that at least a 1/3 of the roots are out of the water.

Set up your Kratky system:

There is not much that you need to have a successful Kratky garden.  Here is a list:

•    A plastic or rubber tub. (Or any container that will hold water including any that you can line with sheet plastic.)

•    A rigid board that fits over the top of your container.  A plastic lid will work fine.

•    A hole saw to cut the board.

•    Net cups (or small plastic cups that you can put lots of small holes in)

•    Rock wool

•    Nutrient solution of choice

Helpful but not necessary:
A water heater for a fish tank…..if you have electricity

Grow plants in a sunny window.

To set up:

Find a sunny spot to set up your planter.  It can be indoors or outside.  When the planter is full it may be hard to move so keep in mind how much sun your plants will need before you begin.  Also keep your planter in a warm place.  The perfect temperature for the water solution is 75 degrees. 

  • Fill the tub with your nutrient solution.  

  •  Cut holes in the board allowing your cups to  hang without falling thru. Holes about three inches apart works well for most plants.  Put the top on the tub.

  • Place the net cups in the holes.  I prefer the two inch net cups.  These cups are used for all greens and many other types of small vegetables and herbs.

If you don’t have net cups, you can use disposable plastic or heavy paper cups.  Determine what part of the cup will be exposed under the cover board.  Put several holes in the exposed part, using a hole punch, utility knife or drill bit.

Examples of hydroponic plants growing.
  • Put moistened rock wool in the net cups.   The rock wool is used to keep the seed moist during germination and to hold the main stem in the net cup. (Do not use rock wool building insulation.)  Alternatives to hydroponic rock wool can be shredded paper towels or light-weight cardboard.  You can use soil in the net cups.  The Kratky system is the only hydroponic system that soil in the net cups will work.

  • Plant your seeds in the medium that you chose.  Keep the seeds/plants moist until the tap root reaches the nutrient solution.

Once the tap root reaches the water you don’t need to do anything else to help the plants grow.

Nutrient solution

This can be a complicated subject.  However, you can start with the simple basics.

There are a few general purpose hydroponic nutrient solutions on the market.  All will work well and are simple to use. There are lots of vegetable specific nutrient solutions available also; however, these can be expensive.

You can easily make your own nutrient solution by making traditional compost tea.  Just make compost tea using worm compost or regular compost. 

Then use the compost tea in a 50/50 mixture with water.  This is a much more economical way of supporting your hydroponic system.  In a non-circulation Kratky system using compost tea, you need to stir the solution regularly to help suspend the nutrients.

The great things about off grid hydroponics with the Kratky method:

•    Can be made from stuff you probably have at home right now.
•    Any size or shape will work so these systems can work in any space.
•    Little maintenance.
•    It makes growing lettuce and any other greens super easy.
•    No electricity needed.

Potential problems with this system:

•    You can only grow small vegetables and greens.
•    The water solution needs to be in the mid 70 degrees, so cold areas could be a problem.
•    The PH level can get high so you may need to adjust with lemon juice or baking soda.

Growing plants with a grow light.

I have been growing using this method for years.  I believe that it’s the best way to start your journey to becoming a hydroponic gardener.  One container will grow salad for your family year round with no electricity.

About the Author

Dorothy Chapman, Moms Indoor Garden

I grew up in Boston and thought I would always be a city girl.  Then after college I discovered how beautiful New Hampshire is and have been here ever since.

I have owned many businesses while raising my son, Jonathan, as a single mom.  And we have been homesteaders for years. Jonathan raised rabbits and sold them to earn money to buy his first “grown up” bike. We try to live simply and as independent as possible while having fun and learning lots along the way.

When Jonathan was 16, we started our first business together.    We designed and built custom greenhouses for small CSAs and homesteaders.  That lead to starting a hydroponic vegetable growing company.

Now he has gone off to college and I have been spending my time writing, teaching and learning all I can about indoor gardening.  I have long been a fan of hydroponic and aquaponic growing.  And of course traditional soil growing is a must.

What do you think?

I’d love to hear what you have to say in the comments.​​

What Other Visitors Have Said

Click below to see contributions from other visitors to this page...

Maintaining the PH level 
Just wondering if some type of fish can be used with the Kratky Method to maintain the PH levels in the watering containers.

Hydroponic Growing Indoors 
I loved this article and am extremely interested in hydroponic growing indoors; but I also live in New Hampshire and I know it will be hard to maintain …

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