How to Build to Mason Jar Hydroponics (6 Easy Steps!)

By: Chenell - Lead Writer and Gardening Advocate

Mason jar hydroponics is a great way to get started growing your own garden, and it’s easy to do. You can use almost any type of container for your hydroponic garden, but I using mason jars is easy since most people have them laying around and if not, they’re a cheap thing to buy. All you need is some soil, water, and some seeds.

While you can buy already put together mason jar hydroponic systems online, it’s really not hard to get started and DIY it. Plus, it can be a great way to teach kids how to grow their own food and what hydroponics is.

How to Create a Hydroponic Mason Jar Garden

Making a Kratky or mason jar hydroponics system is quite simple. And it’s a great way to start an indoor herb garden. Let’s get started!

What Materials Do You Need?

Getting started with your own mason jar hydroponics system doesn’t require much, but there are some things you’re going to need.

mason jar hydroponics materials

Depending on the size of the mason jars, you’ll want to make sure you get the right size net pots as well. When growing leafy greens and herbs, you can use pretty much any size of net pot, but they don’t all fit well into ball jars.

Mason JarNet Pot
8 oz1.5 inch
12 oz2 inch
16 oz2 inch
32 oz3 inch

Once you have all of your materials, let’s jump into the step-by-step guide.

1. Make Sure Your Mason Jars Are Clean

If you’re reusing mason jars from another project, or from storing food, you want to make sure they are really clean. Otherwise, any funk can transfer over to your plants via the water and nutrient solution, and that wouldn’t be very productive.

Even if they’re brand new, make sure to clean them out before using.

2. Cover or Paint the Outside of the Jars

Algae growth can be a real problem when it comes to hydroponics. Since mason jars are clear, once algae appears, it will be able to grow like wildfire since it will have lots of light access.

To mitigate this growth, we need to cover or paint the outside of the jar. You can use something like this fabric to cover the jar, or just grab some black paint at the store.

3. Add Seeds to Rockwool Cubes or Germinate Prior

While growing plants in a mason jar is quite simple, you will need to decide if you’re going to start your seeds before you add them to the jars, or after.

rockwool in net pot

While you can germinate seeds before adding them to the jars, you can absolutely plant the seeds directly into the rockwool cubes and add nutrients once the seeds have germinated later.

Or, you can start seeds elsewhere and once you have a baby plant (i.e. seedlings) you can go ahead and transport them into the mason jars.

3b. Add Expanded Clay Pebbles as Needed

Depending on the size of your net pot, you might need to add some addition material to fill out of the rest of the space.

leca balls expanded clay pellets

Your rockwool cube might be too small for the net pot, and there will be space around it. This isn’t ideal because this will cause an unstable plant, as well as letting light into the jar.

We earn a commission if you click this link and make a purchase at no additional cost to you.

The best solution for this is expanded clay pebbles, also known as hydroton pebbles or leca balls.

These fit in well around rockwool, and also help keep moisture around the plants which is great as they grow.

4. Add Water and Place Net Cup in Water

If you’re starting from seeds, fill the jar enough that the rockwool cube is touching the top of the water. However, you want to make sure there is room for air, otherwise the plant can drown as the germination process continues and the roots form.

Depending on the size of your rockwool cubes, you might need to add clay pebbles around the edges.

5. Make Sure Your Plants Have Enough Light

While a south facing window might get enough light, it’s likely not enough for the plant to grow to maturity. I like to use these inexpensive grow lights as artificial lighting to make sure there is enough like to grow plants. While a grow light isn’t always necessary, if you want your plants to get higher yields and grow faster, I’d recommend it.

6. Add Nutrients

While seeds have everything a plant needs to germinate and get started growing, after the germination process, they do need some added nutrients.

This is where hydroponic liquid nutrients and plant food come in handy. After your plants have their first true set of leaves, it’s time to add some nutrients to the water. While you can add these as soon as your start the seeds, it’s kind of a waste of nutrients until this point because they don’t need them.

Once you have enough plant growth, it’s time to add some nutrients. Generally, you can just follow the instructions on whichever nutrients you plan to use.

Fox Farm Grow Big Hydro Liquid Nutrients

Fox Farm is one of my favorite brands when it comes to both seed starting soil and liquid nutrients.

  • Great for flowering and fruiting plants
  • 3-2-6 NPK Ratio

We earn a commission if you click this link and make a purchase at no additional cost to you.

What is Hydroponics?

Hydroponics is the process of growing vegetables, herbs, and other plants with just water, instead of soil. There are many hydroponic systems you can use, but the Kratky method is most similar to deep water culture, but without the air stone.

It’s an easy way to get started growing plants in a hydroponic setup that doesn’t need pumps and sprayers and more complicated setups.

What Can You Grow in a Mason Jar?

Herbs, salad greens, leafy vegetables and lettuce are great options for growing in a mason jar. However, since a mason jar is small, you don’t want to grow something large like a tomato plant.

Here are some of my favorite things to grow in a mason jar:

  • Lettuce
  • Spinach
  • Cilantro
  • Chives
  • Basil

You can try out a variety of plants using this mason jar hydroponic system, just make sure they aren’t too big and will topple over the jars.

Related: How to Make a Hydroponic 5-Gallon Bucket (EASY Step-by-Step Tutorial)

What is the Kratky Method?

The Kratky method gets its name from Dr. Bernard Kratky, who developed it in the 1990s. It is a type of hydroponic gardening that does not use a pump or any other mechanical device to move the nutrient solution around. The Kratky method works by allowing the solution to flow passively through the plant’s roots.

This is done by using container with a small opening at the top, in this case, a mason jar. The plant is placed in the container so that its roots extend down to the bottom. The nutrient solution stays in the bottom of the container, and is where the roots live as the plant grows.

The Kratky method is simple and easy to set up, and it doesn’t require much of any special equipment or supplies. It can be used to grow a variety of plants, including vegetables, fruits, herbs, and flowers.

Growing hydroponic plants using the mason jar method is a great way to get started with indoor gardening. It’s simple, cheap, and very effective.



Hi - I'm Chenell! I lived in the city for almost a decade, but after moving to the suburbs in 2020, I decided the logical millennial thing to do was to learn how to grow my own avocado toast. That's what this site is all about. 🥑

You can get access to all of my free resources and get some epic dad jokes (and helpful gardening stuff) emailed to you each week by signing up here.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.