Mason jar hydroponics is all the rage this year, and it’s easy to see why. It’s a great way for indoor growers to set up a simple hydroponic garden in their own home, it’s easy, and it lets you finally do something with all those mason jars you started storing in the early 2000s. There are so many wins happening with this simple DIY garden.
If you’re a teacher or a parent, this is also the perfect educational project to get your kids excited about the growing process. There’s a lot to learn from watching a plant grow!
In this article, we’re going through a detailed guide on how to start your own mason jar hydroponics system and start growing your own food in just nine simple steps. So get ready for some cottage core because we’ve got the know-how to put your mason jars to work!
Here’s a great video that walks through the process we’re discussing:
If you want to learn about the type of hydroponics used in this project, please read on. But if you just want to jump ahead to the steps for making your own hydroponics mason jar, I want you to have that option, as well:
- Materials Needed
- Mason Jar Hydroponics Cost
- How To Make A Mason Jar Hydroponic
But wait! Hydroponics without a pump or water stone? While it might sound impossible, a few hydroponic methods don’t require a pump, specifically the wick method and the Kratky method. For this hydroponic mason jar, we’re using the Kratky method. Here’s the skinny on this basic but effective hydroponic system.
How Does The Kratky Method Work?
The Kratky method is considered a passive hydroponic technique, and it’s really the easiest way to get into hydroponics. Like other forms of hydroponics, you start by suspending plants in a net cup above a reservoir filled with nutrient-rich water. Only the tips of the roots touch the water.
With Kratky hydroponics, as the plant grows and the roots develop, the water level goes down. This creates a gap of moist air that then oxygenates the roots and supports faster growth in your plant.
So you don’t need any electricity or pumps, and you don’t even have to water the plant while it’s developing. You should be able to harvest it before the water in the reservoir runs out.
If you’re interested in learning about the science behind the Kratky method, start with this simple video:
It’s a cheap system that still gives you all the benefits of hydroponics, such as using less water and better plant growth, and it requires fewer bells and whistles than most systems.
If you like hydroponics, we recommend you check out some of our reviews for in-home systems, such as our Gardyn review and iHarvest review.
What Plants Work Well With The Kratky Method?
Plenty of plants work with this hydroponic method, but it’s primarily used for fast-growing leafy greens, like romaine lettuce, and smaller plants. This is especially true if you’re growing hydroponic plants in a mason jar. Since you don’t typically refill the water in Kratky hydroponics, you need enough water for the entire life-cycle of the plant – the baby plant and the adult plant are using the same water.
The Kratky Method and Herbs
Basil and a few other fast-growing fresh herbs would work in a small container like a mason jar, as well. Since basil can basically last forever if harvested correctly, you should consider transplanting it when the water in the jar runs out.
If you have limited space and still want to have a larger hydroponic herb garden using the Kratky method, we recommend the Vegebox, a simple and relatively affordable hydroponic system.
Read the Vegebox review here.
The Kratky Method And Large Plants
If you want to try a type of plant with a longer life cycle – peppers, tomatoes, etc. – it’s possible, but you’ll need a larger container. You could use a large tote and drill holes in the top, but that’s a topic for another blog post.
Benefits Of Hydroponics
Growing hydroponically with the mason jar method is an excellent way to improve yields using fewer resources and less space. Here are some of the key benefits:
- You don’t need as much water – this form of hydroponics uses up to 10x less water than traditional growing methods.
- Less space – you can grow plants together and grow them vertically in many hydroponic systems, allowing you to save space by growing up instead of out.
- Root health – The aeration that happens during hydroponics supports healthy root development (when done correctly)
- Microclimate – with your plants growing close together, you develop a humid environment that supports some plant development.
- Produces higher yields
- No weeds – you don’t have to worry about weeds getting into your system when you’re growing hydroponically
- pH control – this is both a benefit and a responsibility. You’ll need to control your pH to give your plants the needed acidity/alkalinity.
What You’ll Need To Get Started
There are a few simple things you’ll need to get started.
Here’s your shopping list if you need to purchase anything for this fun project.
- Mason jars
- Black acrylic paint or chalkboard paint (you can also cover the jars with fabric sleeves!)
- Liquid hydroponic nutrient solution
- Rock wool cubes or peat pellets
- Natural light source or grow light
- Net cups
- Plastic Wrap or Plastic Baggy
- Water – Reverse osmosis water from a filter is the best choice – but it’s not required.
How Much Does It Cost To Make A Hydroponic Mason Jar?
It depends on what materials you currently have and if you’re willing to purchase jars from thrift shops. If you’re buying everything new, including seeds, plastic baggies, a grow light, etc., it could cause $50 or more. But if you only need to purchase a few things – like the nutrients and Rockwool – and if you don’t need an additional light source, it could easily be under $30. Once you have all the material, you can make several hydroponic mason jars for future hydroponic gardening projects.
How To Make A Mason Jar Hydroponic
There are ten basic steps you need to follow to set up this simple hydroponic garden.
Step 1 – Germinate Seedlings
The first thing you need to do is germinate your seeds. You won’t be able to plant your seeds into the jar directly. They need to be seedlings first that can access the water with their roots. To successfully germinate seedlings, start with simple Rockwool cubes or sphagnum peat moss cubes. If you’ve never used Rockewool before, it’s a growing medium that’s great for the germination process.
Start by putting your seeds of choice on a plate – we recommend lettuce or some of your favorite herbs. Then take a toothpick and dip the tip into the water. The water should allow you to pick up an individual seed with the toothpick. Place two seeds per Rockwool cube.
You should place them alongside the edge of the cube’s hole. Here’s a good video that shows how it’s done.
Once you have the seeds inside, use a spray bottle to moisten the seeds lightly. This will help jumpstart the germination process. To improve the germination rate, sprinkle a few pinches of vermiculite in and around the hole. If you do this, spray it one more time lightly with water.
While not required, you can put the Rockwool in either a plastic container, like a Tupperware, or a seed starting tray, which is an excellent way to make a humid environment. After a day, you can add water to the bottom of the container, which the rock wool then absorbs.
A heat map can also improve your germination process. You can check out some options here.
Leafy greens usually sprout between four and ten days. This gives you time to prepare the rest of your materials.
Step 2 – Choose Your Jar
For the jar size, it’s a good idea to use wide-mouth mason jars. We should point out that there are several sizes of wide-mouth mason jars, including the 16 oz (475 ml), the 24 oz (700 ml), the 32 oz (950 ml), and the 64 oz (1.9 )L. These options work fine, but you may need to add water to the smaller 16 oz jars.
There are a few benefits to having a larger mouth on your hydroponic mason jar garden. The first is that it’s easier to clean. And it’s easier to get to your plants if you decide to move them out of the jar long-term.
If you don’t have dozens of mason jars in the back of your cupboard, you can purchase them here:
The key here is that the mouth of your mason jar matches – or is very similar to – the size of your net cup. You also want to make sure you have a lid ring, which helps when painting your mason jar.
Step 3 – Cover Your Jars
Take your mason jar, unscrew the lid ring and top, and then place either plastic baggies or plastic wrap between the lid and the jar. The purpose of this is to keep the paint (the next step) out of the inside of the jar.
Step 4 – Paint Your Jars
Then paint the outside of your mason jars. I think that acrylic paint works well and looks very sleek. You could also use chalk paint, which can be a good option if you want to label your mason jar with chalk.
The purpose of the black paint is to keep light from entering the nutrient-rich water. The light inside the jar could (and most likely will) create algae growth, which can be a pain for growing. So spray your bottle with the black paint before getting started.
Make sure it has plenty of time to dry before continuing your project.
Step 5 – Uncover Your Jars And Add Water
Fill up your jar until it has about 4.25″ from the jar’s mouth. The reason for this is that a 3″ net cup is 4″ deep, and you want the slightest gap of air between the bottom of the net pot and the water. This will be just enough for your plant’s roots to hang into the water below.
Depending on the roots of the plant, you may need to adjust the water line slightly – a little more for shorter roots and a little less for longer roots. For very short roots, you can actually fill your jar all the way up to the base of the net cut, as there is still a pocket of air between the growing medium and the net cup plastic.
In a proper Kratky system, you would only fill your jar once with water during the plant’s life cycle. But there are several reports of growers adding water if their jar starts to run out of it. Ideally, though, your water should, at the very least, last a long time.
Important: Keep track of how much water you’re using. This will determine how much liquid nutrients you add.
Step 6 – Prepare Your Nutrient-Rich Solution
When growing in soil, your plant can draw from nutrients and minerals to help it grow and flourish. This isn’t the case with hydroponics. The grow medium you’re using is great for seedling and sprouts, but it doesn’t have any of its own nutrients.
You’ll need to add liquid nutrients to your water to give your beautiful green plants the plant food they need.
When adding hydroponic nutrients to your water, simply follow the directions on the bottle for application. Most liquid nutrients providers will tell you to add more of their product every few weeks. While this is true for most forms of hydroponic systems, the Kratky method should technically have all the necessary nutrients when you start on day one.
That said, the jury is still out on this! And since most leafy greens take about a month or more to mature, you may need to add another feeding for your plants. The beauty is that once you have the materials, you can have several plants growing in mason jars simultaneously. Experiment with different water levels and plant feedings to see what works the best for specific plants.
We recommended General Hydroponics Flora Grow above, but any liquid nutrient mix, such as AeroGarden’s option, will work well. My household has a small arsenal of AeroGarden liquid nutrients, so we’re using that on this project.
Step 7 – Add Net Pot
Now add your net pot to the top of the jar, which will hold your plant and growing medium. If you’re using the wide mouth options listed above, you’ll want to use a 3″ net pot, which should fit snugly into the top of the jar.
Step 8 – Add Growing Medium With Plants
A growing medium is just the substance that holds your plant’s roots. With hydroponics, you will need to use a form of grow media, such as hydroton pebbles (LECA) or Rockwool, peat moss, etc. If you’re following these steps, you likely used Rockwool, which is a great option.
For most beginners, I recommend Rockwool. Clay pebbles are fine too, and they have a very classy look that some growers enjoy.
Step 9 – Place Your Hydroponic Mason Jar
Your plants need light to survive and thrive. If you’re using artificial lighting and growing leafy greens, you typically need the lights on for 14-16 hours a day and off the rest of the day. We recommend you use an LED grow light to give your plants the full-spectrum rays they crave.
Normally, I don’t like the purple or “blurple” lights, but some indoor gardeners love them. Here are some affordable options if you need some extra light:
If you’re a little more serious about your indoor growing, here are some fancier LED options. I would only recommend these if you plan to grow this hobby beyond hydroponic mason jars.
The Best Small LED Grow Light
That said, grow lights are rarely as good as a good o’l fashioned sunny window. You typically want direct sunlight for greens, which is generally considered 5+ hours a day in a sunny spot. A south-facing window sill is an ideal option for growers.
Step 10 – Caring For Your Hydroponic Mason Jar
The biggest challenge most Kratky hydroponics growers face is getting the roots to sit in the net pot but hang below into the water – and with a layer of air between water and net cup. This is usually a struggle because the roots aren’t always long enough. One way to prevent this issue is to let your seedling grow a little longer to give them time for larger root growth.
Worst case scenario, you can have your water a little higher in the jar. The space between the rock wool and the net cup also acts as an air pocket, so the gap below the net cup is nice to have – but not necessarily a requirement.
Will You Need To Add Water?
In a true Kratky hydroponic system, you wouldn’t add water or nutrients throughout the process. But you typically need at least 4 liters of water per plant with this system, which is way more than a 16 oz jar can hold. To deal with this, add water when the jar starts to get low (don’t let it run out!).
Don’t fill the jar all the way up with water, as the roots need a gap of oxygen. We typically recommend that you fill it halfway. At this point, you can also add liquid nutrients based on the amount of water included.
What Do You Do When The Plant Roots Are Too Big?
You should always be ready to adjust your process to meet your plant’s needs. If the roots don’t have enough room, it may be time to move your plant – either to a larger jar, a more traditional hydroponic system, or to a soil/potting mix.
Can You Grow Lettuce In A Mason Jar?
Lettuce and other leafy greens are great options to grow in a hydroponic mason jar. This method of growing is called Kratky hydroponics, meaning it doesn’t require electricity or pumps. Lettuce works well in this system because it has a very fast-growing cycle. Larger plants or flowering plants can theoretically be grown using the Kratky system, but we don’t recommend growing them in a mason jar. For those, you’ll need a bigger tub or tote.
These amazing jars are an excellent first hydroponic setup for new growers. They also make great gifts for holidays. Who wouldn’t want a simple spinach garden or an artistic herb mason jar? What’s more, this system is easy and incredibly affordable compared to other hydroponic methods. So whether you’re growing for the first time, interested in hydroponics, or you just want to add more fresh greens and veggies in your life, give the hydroponic mason jar a try!
And if you have any pictures of your mason jar hydroponics, we want to see them! Send them in an email to firstname.lastname@example.org, and we may include them in this article!