Quick and Easy Mason Jar Hydroponic Setup

Want to try out hydroponics, but don’t want to spend much? Honestly it’s a big field with lots of complex terms and companies selling you the “next must have” item…. Let me help you create your first hydroponic setup without spending much, or maybe even without spending a single dollar!

Our goal is to create a “set and forget” system to grow lettuce.

The Supplies

The Container

Most people will do their first hydroponics with mason jars. They are such a versatile jar that pretty much every house has one, and they are cheap!

Photo of a mason jar.

If you haven’t got a mason jar, you can get this 34oz or 1L one from Ikea for $3.99, or this 1.9qt or 1.8L jar from Ikea for $4.99. Alternatively you could buy this 32oz double pack from Amazon for $8.

I personally recommend the largest jar possible; it’s more “set and forget”. Lettuce roots don’t need too much space to grow, but depending upon your environment and its growth rate you may find yourself adding water to a small jar every so often.

Hydroponic containers have to be opaque and black to stop algae growth… but you won’t find any mason jar like that. Instead, wrap the jar well with aluminium foil, or even paint a couple layers of black gesso or acrylic paint on the outside! If use chalk paint and you can later write or decorate your jars with chalk pens.

Week 1 Kratky Lettuce Compared
I painted these mason jars with two layers of black acrylic paint.

The Yoghurt Cup or Net Cup

If you have plenty of plants around your home, you may have a net cup already. They are often those little plastic cups with slots or holes in them that come with smaller plants. Make sure it fits. I use these 2″ wide-rim cups from CZ Garden.

Alternatively, you can recycle a plastic yoghurt cup. To be safe, please check What Plastic Should I use for Hydroponics? as not all plastics are safe to reuse. In the picture below you can see how I reused a sour cream cup:

Sour Cream/Yoghurt Cup Recycle for Mason Jar Kratky
Sour Cream/Yoghurt Cup Recycle for Mason Jar Kratky

The Nutrients

Plants will often get all their nutrients from the soil you plant them in, although sometimes you will add fertilizers or compost. Hydroponics removes the soil from the growing process, so you need to come up with an alternative way to feed the plants nutrients.

General Hydroponics Nutrient Combo Pack
General Hydroponics Nutrient Combo Pack

This is probably the only product that you may need to buy. If it’s your absolute first time attempting hydroponics you can probably get away with something like AeroGarden Liquid Nutrients (3 oz), though I would honestly encourage you to invest in a proper hydroponic solution like General Hydroponics Flora Grow, Bloom, Micro Combo Fertilizer set. This combo pack will last you a very long time, especially if you aren’t growing hydroponics seriously.

The Plant

Next you need to decide what plant you are going to grow: lettuce and basil are some of the most common plants for people to try for their first grow since they are fast growing, cheap and easy to manage. With the right setup you can even grow big plants like tomatoes (but they won’t grow in mason jars, sorry)!

GettyStewart has a great post about How to Regrow Romaine Lettuce from the Stem. She does point out that regrowing from a stem won’t produce leaves as large as store bought plants; and this probably has to do with the amounts of nutrients and lights that a store-bought plant receives compared to a stem in plain water.

I prefer to grow from seed; it has a fairly high success rate and only takes two to three weeks before I am harvesting. You can buy packs of various seeds fairly cheap, or individual packs from stores such as Botanical Interests.

If you live in Kuwait as well, you can read my post on where to buy organic seeds in Kuwait.

The Grow Medium

Hydroponics is mostly about removing the soil from growing plants, but you can’t just plop them into the water and hope for them to survive (some plants do, but most wont)!

You will need some form of grow medium. There are several different options with the easiest and most common being peat moss, rock wool and clay pebbles.

I regularly use Jiffy 7 Peat Pellets. They come in various sizes. Since the peat pellet is too small to fill up my entire DIY net cup, I pack clay pebbles around it. Alternatively you can use rock wool. You can simply cut up extra rock wool cubes to fill any spaces in your net cup. If you don’t want to cut up the extra rock wool, you can of course use clay pebbles as well.

It’s important to fill up the entire cup; we want to make sure that no light will get beyond the grow medium and into the mason jar.

The Light

Most people will put their mason jar and plant in the window, and generally there will be sufficient light for plant growth. Unfortunately my kitchen window is underneath a building overhang and thus gets very little light; so I need a grow light.

Buying grow lights is a bit more of a complex issue. I’ve written The Beginners Guide To Hydroponic Lights series that explore lights in detail in a very user-friendly manner. I’ve personally bought two different lamps: the Fissioning LED Grow Light and the Bozily LED Grow Light. Low strength beginner lights can be quite cheap; you may even be able to buy a normal bulb and relocate a lamp.

Build The Setup

(Optional) Paint Your Mason Jars

If you opted to paint your mason jars black, now is the time. Paint only the outside of the jar, remember that the paint itself is unlikely to be food-safe. Paint right up to the rim of the jar. Paint two to the three layers so that no light can leak inside.

Cut Your DIY Grow Cup

If you are using a recycled yoghurt cup, its time to cut some slits and holes in the bottom of the cup. Slits are generally better as they hold the grow medium without spilling, but still provide enough space for roots to grow through.

Sterilise Everything

Any non-living supply should be sterilised; jars, containers, and grow medium. The easiest way to do this is to submerge everything in hot water.

Prepare The Nutrients

In the post The Best Nutrients and Ratios for Hydroponics? I discuss how to measure out the General Hydroponics Flora Grow, Bloom, Micro Combo Fertilizer set. Since we are using a “set and forget” method, we need to use the nutrient ratio for vegetative growth. Mix 1 gallon, or 3790ml, of water with 3 teaspoons of FloraGro, 2 teaspoons of FloraMicro and 1 teaspoon of FloraBloom.

Fill your mason jar until the water level passes the bottom of the grow cup or yoghurt container by approximately .25″ or 1cm.

If you have excess water left over, you can water other plants with the mixture or store it to top up your lettuce water. You should not pour it down a drain! I store my excess nutrient mixes as I live in a dry climate and find water tends to evaporate faster than the plants are able to absorb.

Plant Your Seed

Make a small hole, usually about .25″ or 1cm deep, in your grow medium. Drop two to three seeds in and fluff grow material on top to cover lightly. Not all seeds with germinate, so it’s generally a good idea to put at least two seeds. If multiple sprout, you can always transplant or pull out the extra growth.

Place your grow medium in the centre of the cup, ensuring that the bottom of the grow medium is in contact with the water. Surround your grow medium with clay pebbles, or more rock wool.

Set and Forget

Place your mason jar somewhere bright, like a window.

Week 2 Kratky Lettuce Compared
Week 2 Kratky Lettuce Compared

And thats it! Over the next few days your plant should sprout. Some plants do take longer to sprout, so check your seed packet. My basil usually sprouts in about 5 days; at least you can see the tiniest of plants emerging around then.

Problem Solving

If your plant didn’t sprout:

  • You may need to wait longer; check on the seed packet for how long it takes for that variety of plant to sprout. Some species can take 20 or more days!
  • Make sure your grow medium is moist the entire time the seeds are sprouting; if you live in a very dry environment your water level may evaporate too fast for the seedlings to produce roots.
  • You could also have some bad seeds, try refilling your jar and planting more or new seeds.

If you notice your plants becoming wilted, chances are the water level is evaporating faster than they can absorb. Fill up your jar a little at the time! It’s very important to not fill the jar up the entire way; as the water level decreases the plant will grow water-roots and air-roots. If you submerge your air-roots in water your plant will literally drown. If you want to maintain your water level, I suggest the half-way point of the jar.

If your plant seems to be growing long leaves that aren’t very wide, you may not have enough light. Check out my post Do I Need Grow Lights? where I teach you how to measure the amount of light in your room.

Expected Grow Times of Kratky Hydroponic Plants

I’d like to figure out how fast I can expect my plants to grow. Most seed packets and websites tell you how fast seeds grow assuming you are using soil, But hydroponics can grow up to 50% faster!

I doubt very much that my first hydroponic plants will grow 50% faster, however that doesn’t mean that I couldn’t expect to start harvesting from roughly that time onwards. You rarely need to wait until the plant reaches full maturity before you can harvest; just pull off leaves as needed and let the plant keep growing. I added “Potential Maturity” to the table below, but realistically that’s when I suspect I may be able to get my first harvest.

Earlier in the week I announced that we were hoping to grow the following vegetables and fruits in our Kratky hydroponic tubs:

  • Amaranth, Red Leaf
  • Basil, Purple Petra
  • Cucumber, Lemon Cucumber
  • Lettuce, New Red Fire
  • Lettuce, Red Sails
  • Spinach, Matador
  • Spinach, Lavewa
  • Swiss Chard, Bright Lights
  • Tomato, San Marzano

All of our seeds were purchased from Sustainable Organic Q8, and appear to have been imported from Botanical Interests. You can read more about my search from seeds in the post Where to buy organic seeds in Kuwait.

Days To MaturityPotential Maturity
Amaranth, Red Leaf90-11045-60
Basil, Purple Petra45-5523-28
Cucumber, Lemon6532
Lettuce, New Red Fire5527
Lettuce, Red Sails4523
Spinach, Matador28-4814-24
Spinach, Lavewa28-4514-24
Swiss Chard, Bright Lights5226
Tomato, San Marzano80-9040-45

I’d really to have some plants growing, or even harvestable, by late September/early October. Thats approximately 50-60 days from now. We have space for 2 large plants, along with at least 3 smaller plants and maximum of 5 plants.

San Marzano Tomato Artwork, Courtesy of Botanical Interests
San Marzano Tomato Artwork, Courtesy of Botanical Interests

The San Marzano Tomatoes are planned as a permanent setup, so these will take priority in one of the largest plant spaces. This tomato plant will be approximately 5-6 feet (1.5-1.8m) in height!

Lemon Cucumber Artwork, Courtesy of Botanical Interests
Lemon Cucumber Artwork, Courtesy of Botanical Interests

Whilst not quite as large as the tomatoes, the Lemon Cucumbers will stand about 3-4 feet (0.9-1.2m) in height. This will fill my second large grow area.

There are debates online about which spinach is “better”; matador apparently grows better in many conditions, but the Lavewa looks prettier and is slightly tastier. We want to test both of these spinaches side by side. They grow at the same rate, so we will test both the Lavewa Spinach and the Matador Spinach together.

Amaranth Artwork, Courtesy of Botanical Interests
Amaranth Artwork, Courtesy of Botanical Interests

I want to stagger the harvesting of my plants; I don’t want all my fresh leaf plants to mature at the same time, and then go one to two months with little food. So I have decided that I will start the Amaranth as well for this first hydroponic growth cycle. Granted, with its growth speed, I may be able to grow two batches of spinach by the time it reaches full maturity.

If I can fit anymore plants in my grow area I will add the Swiss Chard and the New Red Fire Lettuce.

What about you?

What are you growing this season? Did you calculate how long it takes to grow? Did you have to plan around seasons and temperature outdoors? Let me know what you’re growing!

Where to buy organic seeds in Kuwait

After researching a bit, and probably jumping into the water too fast when it comes to buying products like grow lights, I have purchased some seeds to grow in my Krakty hydroponic room setup.

Buying seeds was a specific hassle in Kuwait; the very few and limited stores that sold seeds only sold very common varieties. Think Beefsteak tomatoes; the probably most common tomato you can find at any supermarket. Since such tomatoes are so easy to buy, I want to grow something more unique.

In fact, we even found a nursery selling seeds with the giant warning label on the back: “Warning. Treated with poison. Do not consume or grow food products from these.” What?!

In the end we found a company called Sustainable Organic Q8 that seems to import from reliable producers.

The initial seeds that we have ordered are:

  • Amaranth, Red Leaf
  • Basil, Purple Petra
  • Cucumber, Lemon Cucumber
  • Lettuce, New Red Fire
  • Lettuce, Red Sails
  • Spinach, Matador
  • Spinach, Lavewa
  • Swiss Chard, Bright Lights
  • Tomato, San Marzano

Hopefully within the week we will have the buckets and grow lights and started growing!