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mason jar hydroponic plants

Mason Jar Hydroponics (The Kratky Method): Easiest Hydroponic System

Another name for a mason jar hydroponics system is the Kratky method. By some, it’s considered the 7th hydroponic system, the cheapest and easiest of them all.

In reality, if you’re searching for types of hydroponics systems, more often than not, you’re not going to find it on the list. You’ll only learn about the ones used by commercial growers, like DWC, wicks, NFT, ebb and flow, drips, and aeroponics.

I should tell you right from the start that if you want to grow bigger plants with the Kratky method (tomatoes, cucumbers, peppers, eggplants) then you should replace the mason jars with a 5-gallon storage tote. The principles and the method stays the same, only the container is different.

Mason Jar Hydroponics: What You Need

1. Jars: Bedoo Wide Mouth Mason Jars 32 oz

If you don’t want to buy quart jars with wide mouths, maybe you have some bigger jars around the house, maybe from some coffee that you bought or things like that.

2. Rockwool cubes: 1.5” Rockwool Starter Plugs for Hydroponics

These are the easiest and the most accessible for germinating seeds in but you can also use oasis grow cubes.

3. 3-inch net pots: Vivosun 3 Inch Net Pots

These are the little cups that are holding the rockwool cubes with the seedlings. This is the component that sustains the plants while they’re growing to maturity.

4. Hydroton (expanded clay pebbles): Hydroton Original Clay Pebbles

In order to make the rockwool cubes with the seedlings stable in the 3-inch net pots you should add some clay pebbles at the bottom of the net pots.

5. Nutrient solution for hydroponics: Fox Farm FX14094 Grow Big Hydro Liquid Concentrate

This is what makes the plants grow. It’s absolutely fundamental to hydroponics. You’ll usually fill up the jar with water and nutrient solution just once and then let the roots take what they need. As the level of the solution decreases, the roots will also receive oxygen.

6. Grow lights: Vivosun T5 Grow Lights 2 ft

If you can’t place your jars somewhere to receive about 6-8 hours of sunlight each day then you’ll have to buy some grow lights to replace that natural light. Grow lights are especially necessary during the winter.

Mason Jar Hydroponics: Fundamentals

how to grow mason jar herbs using the Kratky method

Hydroponic basil grown in a mason jar using the Kratky method

In this article we’re going to talk about how to hydroponically grow herbs in mason jars. Lettuce and leafy greens can also be grown in this set-up. And a few other plants. Even strawberries if you want to try something a bit more demanding of your time and attention.

If you want a visual guide on how to grow plants in a mason jar, check out this YouTube video, it’s really nicely made.

Main Components:

  • quart jars with wide mouths (32 oz)
  • rockwool cubes for germination
  • 3-inch net cups
  • expanded clay aggregate (hydroton) as the additional growing medium
  • nutrient solution for hydroponics
  • LED grow lights full spectrum

I definitely recommend buying the wider mouth mason jars because they offer plants plenty of room to grow. They will also go perfectly with 3-inch net cups.

The important thing to remember is that the net cups must fit perfectly over the mouth so that nothing can go through into into the water.

If this is your first attempt at hydroponics, I recommend buying a nutrient solution for hydroponics and following the instructions that are written on the packaging for mixing and how much to use.

It’s the easiest way and a hydroponic solution in powdered form might seem expensive at first but it will last a long time. Some instructions will just have you dissolve a spoon per one gallon of water. It really depends on what nutrient solution you’re buying so, read the instructions and follow those precisely.

How to Hydroponically Grow Plants in Mason Jars

  • germinate the seeds in rockwool cubes
  • you can also attempt growing herbs in mason jars from cuttings in which case you don’t need to germinate the seeds but, for plants like lettuce, you need to walk the long road, starting with germination in rockwool cubes
  • when the germination is done, it’s time for transplanting
  • you should transplant the seedlings together with the rockwool cubes, there’s no point in removing the seedlings from the cubes
  • 32 oz quart jars with wide mouths – the number of jars will match the number of rockwool cubes with seedlings
  • you can also use smaller jars but there’s one thing you need to pay attention to depending on the type of jars you’re using to grow plants: the size of the net cups
  • get 3 inch net cups for quart jars with wide mouths and get 2 inch net cups for smaller jars with a smaller mouth
  • the net cups are the place where you will transplant the rockwool cubes with the seedlings
  • if you’re using 3 inch net cups you should also add some expanded clay aggregate pebbles to keep the rockwool upright and stable
  • nutrient solution for hydroponics – you can buy it or you can make your own if you want to save even more money

Now, it’s time to put it all together:

  • fill in the jars with water and nutrient solution
  • the water with nutrient solution should reach just above the bottom of the net cups, 1 inch above is good, the growing medium (hydroton + rockwool cubes) will fill up on water and nutrients and feed them to the roots of the plants
  • wrap up the jars in colorful paper to prevent algae growth – you can also use aluminum foil to reflect the light or you can spray paint them
  • place the mason jars in direct sunlight on the window sill or use LED grow lights if you don’t have access to direct sunlight
  • as the roots and plants grow, the water and nutrients level will decrease – this depletion of water is what will provide the roots with the needed oxygen
  • so, the water and nutrients are not replenished as the plants continue to grow

Plants You Can Grow in Mason Jars Hydroponics

mason jar hydroponic plants

In terms of plants you can grow in hydroponic mason jars, the choice is more varied than you might expect.

A wick system will be a bit more restrictive than the Kratky method.

These are the plants that you can hydroponically grow with the Kratky method, with mason jars as containers:

  • lettuce is the best to be grown in mason jar hydroponics systems – I recommend starting off with lettuce varieties like loose leaf lettuce, butterhead, romaine or lollo
  • spinach is another leafy green that will give a good yield – you can expect to harvest spinach in about 40 days, since germination only takes about a week, or, if you want to harvest it as baby spinach, it only takes about 15-20 days
  • kale
  • bok choy
  • herbs (basil, mint, parsley, cilantro, thyme, chives, rosemary) – after leafy greens, herbs are the second best choice to grow in hydroponic mason jars
  • hot peppers
  • cherry tomato varieties – they’re not as easy to grow as leafy greens and herbs but it’s possible to grow them in mason jar hydroponics, although bigger containers will do much better with cherry tomatoes; depending on how quickly the water is consumed, you might need to replenish it with nutrient solution once a week or once every 2 weeks
  • strawberries – they require more attention because a pH level of 5.5 to 6.2 is needed and they need to be pollinated by hand by brushing pollen from male flowers into female flowers

If you want to teach your children about how to take care of an indoor garden, this mason jar hydroponics system is the perfect method. You’ll have so much fun as a family.

If you’re committed to doing your best, you should also consider getting a pH meter or a pH control kit. For fine-tuning the hydroponic solution, you can buy pH Up and pH Down bottles.

You can also go the traditional route of growing plants in mason jars, you can fill them up with soil instead of water. This website has a good guide on that. I am a bit concerned that there’s no drainage for the soil but they say that they use small pebbles or stones so, it should work.

Why You Should Consider Mason Jar Hydroponics

mason jar herbs

The Kratky method realized with mason jars as containers is one of the easiest and most accessible hydroponic indoor arrangement.

This is a lot like the deep water culture system with buckets as containers but without the air pump and air stone. The Kratky method can also use buckets as containers instead of mason jars.

But if you’re using mason jars to grow plants hydroponically, it’s on a much smaller scale so, it can fit in smaller spaces. Deep water culture buckets are usually placed in a garage or in a greenhouse.

Moreover,

If you want to experience hydroponics but don’t want to spend money on a hydroponic indoor garden, which can be quite expensive, I definitely recommend turning to mason jars hydroponics.

Mason jars are definitely the inexpensive alternative to hydroponic indoor garden kits, like the ones from iDoo or AeroGarden.

It’s why I recommended this method as one of the easiest in how to grow hydroponic lettuce and how to grow hydroponic basil.

You have the possibility of growing as many plants as you want, as many as you can fit in your house or apartment.

This is actually a perfect simple hydroponic system for apartments and beginners, you can have your own mini-garden indoors even if you don’t live in a huge space.

Another major advantage is that this simple system doesn’t involve any moving parts. There’s no need for water pumps, air pumps, air stones or tubing.

If you want to graduate to a superior level of hydroponics systems, you will move on to DWC or wicks or NFT or ebb and flow or drips. The Kratky method with mason jars can be your stepping stone.

FAQs on Mason Jar Hydroponics

Let’s make a small recap on this post by answering a few interesting questions on mason jar hydroponics. You will be able to understand this simple system even better.

Q. Can I grow lettuce in mason jars?

Lettuce is actually one of the first vegetables that people start growing hydroponically. It’s a plant that loves water so, it’s absolutely perfect for growing in mason jars filled with water and nutrient solution. Growing lettuce in hydroponic mason jars doesn’t require a lot of work or any special requirements: it has a permissible 6.0 to 7.0 pH, it’s a cool plant that should be grown in temperatures under 75 degrees F, and it requires 16-18 hours of LED grow lights.

Q. How do you make a hydroponic herb garden mason jar?

The main components for making a hydroponics herb garden mason jar are: quart jars with wide mouths (32 oz), rockwool cubes for germination, 3-inch net cups, expanded clay aggregate (hydroton) as the additional growing medium, nutrient solution for hydroponics, LED grow lights full spectrum. If you’re growing the herbs from cuttings, you can skip germination in rockwool and grow the cuttings in aggregate clay pebbles directly.

Q. Can you use mason jar for plants?

Yes, you can use mason jars to grow plants indoors in soil or you can use them for making a simple, cheap hydroponic system.

Mason Jar Hydroponics Alternatives

If you want another DIY rudimentary system, the best alternative to mason jar hydroponics is making a wicks system from plastic bottles as containers.

The advantage with plastic bottles as containers is that you don’t need to buy net cups. The upper half of the cut plastic bottle will serve as the place where the clay pellets with the rockwool cubes are placed.

And you don’t have to spend any money on jars.

You can watch several YouTube videos on this method, as well. So, if you’re not ready to invest in some quart jars with wide mouths with for mason jar hydroponics, you can try the wick system in plastic bottles.