Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Week 3

I wouldn’t have believed it a month ago when you said I could grow tomatoes so easily in Kuwait’s hot desert weather; but here I am, just growing tomatoes. Of course I cheated a little by growing them inside the house, in a climate controlled area… and then I removed the soil and decided to grow them hydroponically.

And they are still growing!

My little plant babies are now three weeks old, and wow have they grown. This was them only one week ago:

Their stems had just started to turn brownish tinged close to the cloning collars. They both also had two new branches.

And this is them now, at three weeks old:

I just can’t believe how fast they are growing. I can turn my grow lights off at night, then when I re-enter in the morning they have grown an entire branch! No joking, I have seen an entire baby branch just pop up in the space of a few hours.

I have preemptively placed their first trellis support bars. Since we are using custom painted Ikea Ivar cabinets to hold our plants, we bought the bottle rack as a DIY trellis. This provides some basic support for the plants, and lets me tie them in place. We can also easily raise or lower the bottle rack as needed, and even add more as the tomatoes grow in height.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

This is the weaker of the two tomatoes; he isn’t growing as fast. He now has four branches, two of which are fairly large. I noticed that once the dominate grower had put out one or two smaller branches, he had substantial increase in growth speed. I expect this one would probably grow much faster in the coming week.

The dominate grower is outpacing him pretty fast; he has a total of nine little branches all emerging. He’s also about 2″ (5cm) taller than his sibling. His centre branch is just touching the trellis bars, so hopefully in the next few days he will be resting against it and can be supported with the tie.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

Both tomato plants seem to be developing some good root structures. I couldn’t lift the buckets out too high as the trellis bars are now in the way, but you can see the roots extend much further down into the bucket and nutrient water. The roots are nice and white, which is a sign of plant health when it comes to hydroponics.

San Marzano Tomato Week 3, In Kratky Hydroponics
San Marzano Tomato Week 3, In Kratky Hydroponics

Have you grown tomatoes hydroponically, or maybe traditionally in soil? Do you have any tips to share with a first-time grower?

Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Week 2

One week ago I transplanted San Marzano tomatoes into a Kratky hydroponic container, and we were left wondering if they survived. Here is it in Week 1:

San Marzano Transplanted into Kratky, Week 1
San Marzano Transplanted into Kratky, Week 1

I’m glad to say that not only did they survive, they have started growing wonderfully!

San Marzano Tomato Seedling Week 2, In Kratky Hydrponics
San Marzano Tomato Seedling Week 2, In Kratky Hydrponics

The two tiny specks of leaves became much larger, and we now have four to five tiny new leaves beginning to grow on each section. The original leaves have definitely turned into stems, and hopefully they will eventually become branches.

San Marzano Tomato Seedling Week 2, In Kratky Hydrponics
San Marzano Tomato Seedling Week 2, In Kratky Hydrponics

The trunk of the tomato (can it be called a trunk yet?) is about three times the thickness than when I transplanted it. The fine fuzz on it has also thickened up and become much more apparent. I don’t know enough about botany to explain what this section does – if you know please let me know in the comments!

San Marzano Tomato Seedling Week 2, In Kratky Hydroponics
San Marzano Tomato Seedling Week 2, In Kratky Hydroponics

I’m not brave enough to lift the lid and look under. The water level was filled right to the brim of the container, and I mean right to the point of overflowing. I’m worried that if I lift it I will not only introduce light to the system, I may disturb the seedling as well. Maybe next week we can check out if there is growth.

Have you grown any tomatoes in hydroponics? I’d love to know your success (and failure) stories.

Transplanting Seedlings for Hydroponics Tips

A lot of people use hydroponic machines to start seedlings. Some people will start seedlings to transplant outdoors, and others will start seedings to transplant to larger containers. This post proves that I’m no exception: I just transplanted my San Marzano seedlings into their final Kratky hydroponic home.

Each method of transplanting has its own risks, as discussed below. By far the biggest risk of all is killing your innocent-baby plant. But if you follow the tips listed below, you will minimise the risk of being a plant slaughterer.

Also know that not all plants should be transplanted as some plants can’t handle root disturbance well, like spinach. You should only ever transplant healthy plants.

From Hydroponics to Soil

This is one of the most common methods to grow your plants; starting your delicate seedlings indoors and then planting in your garden when they are old enough to fend for themselves.

You should only transplant once roots have emerged from the bottom of the grow medium. If you wait too long then you risk stressing your plants.

Use grow medium that can be planted outdoors; trying to remove the plant from grow medium can be quite damaging to the roots. I tried separating my lettuce seedlings from the grow medium, and they definitely experienced shock.

Help your plants grow new roots, fast, by using root growth hormones. Whilst I haven’t used hormones on my own plants I have read online people recommending SUPERthrive Plant Vitamin Solution and HydroDynamics Clonex Rooting Gel.

Keep your soil well watered for a few days. You want the soil slightly damp, but not holding so much water that root or mould will grow. If your soil is well draining then consider watering a couple times a day.

You can also add a diluted nutrient solution to your water to help the plant get any extra energy it might need to grow new leaves and roots. This can be the same nutrients that your seedlings were growing in. Don’t give them full strength nutrients yet, as too much can actually harm your plants.

From Soil to Hydroponics

It is possible to transplant from soil to hydroponics, though many hydroponic growers like to keep their grow areas sterilised. Introducing dirt grown plants into a grow room can also bring the risk of unwanted bugs and diseases, potentially harming other plants (or even loosing all your crops!). I have personally lost entire crops from an exposure of an aphid infected plant, and so now I will only grow new plants from seeds.

Let your plant’s soil dry out prior to transplanting; dry soil is much easier to clean any dirt from the roots than wet. Once you have removed as much dirt as possible, then submerged the roots into a bucket of water and rinse any remaining residue. The roots need to be as clean as possible; dirt will contain bugs, algae, and can even damage some hydroponic pump systems.

Place your plant into a net pot and gently pull any long roots through the net pot holes. If the roots are fragile and just break, it’s better to keep them inside the net pot than risk damaging them. cover thoroughly with grow medium like clay pebbles. You need to ensure that no light can enter into your water reservoir.

Depending upon your hydroponic setup, make sure that air is still getting to the roots. Many people will use an air-stone to oxygenate your plant roots. If you are doing the kratky method then you should only submerge the lower roots and net pot, keeping at least half above the waterline to avoid drowning the plant.

Finally, your plant is going to go into shock, potentially a lot. It may look like you’ve killed the plant, with lots of leaves falling off or browning. Give it time and in most cases the plant will recover, anywhere from two days to a couple weeks. You may lose the original leaves as the plant will often abandon preserving those to focus on more important root growth.

From Hydroponics to Hydroponics

This will often be the easiest way to transplant seedlings, if you have planned out your plant growth before hand. The time to transplant is when the roots begin to emerge. Hydroponic roots are very fragile, so if they extend beyond the net cup then they are almost guaranteed to break.

If you know that your plant will need transplanting, try starting the seedlings in the final grow media such as rock wool. Simply transplant the entire cup or simply lift out the plant from one cup and transfer contents to a larger cup, adding more clay pebbles to block out any light.

Don’t make my mistake and wait too long: I transplanted some lettuce from peat moss (started in my Aerogarden) to cloning collars. The process or removing the lettuce seedlings from the Aerogarden net cups and washing out the peat moss caused them to mostly lose their fine roots. They looked dead for the first few days. It took them nearly a week to recover and start showing new growth.

Have you transplanted plants before? Share some of your tips in the comments below.

Transplanting San Marzano Tomatoes into Kratky Hydroponics

So far in my hydroponic journey I have been starting my seeds in my Aerogarden Bounty; it has the highest rate of success. There is just something this machine does better than I can, which is also a reason why I recommend anyone interested in hydroponics without the scary setup look at the Aerogarden product range.

On the 1st August 2019 I planted some San Marzano tomato seeds in my Aerogarden. It’s been a week (a bit longer by the time I got around to writing this article, but photos taken on date) and it’s time to transplant my tomatoes into their final home. Exciting!

When I previously transplanted some lettuce between the Aerogarden and Kratky setup, it didn’t go as well as I hoped: my poor plants suffered a lot of shock. I since learnt that I had let the roots get too large, and the transplanting process really hurt the plants (by ripping the roots right off!).

After learning from all my recent plant murder attempts, I am transplanting the tomatoes the moment the roots emerged; one week after planting the seedlings!

Here are the tomatoes just prior to transplanting. The seedling wearing his seed pod as a hat is so cute!

My kratky container is the Klämtare Box With Lid from Ikea. It’s a great option as the plastic they use is food-safe. It’s also large enough for two tomato plants.

I used a 3″ hole saw to drill into the lid, since I was using a 3″ net cup. You could always buy a hole saw kit with several sized pieces (I bought one of these kits as well). I also chose to transplant from the peat moss to a cloning collar, though this was a personal choice. Underneath the cloning collar was clay pebbles; it is recommended to add some grow medium underneath the collar in case you ever need to remove it, as it provides significant support to the plant and sudden removal could mean the plant falls over!

San Marzano Transplanted into Kratky, Week 1
San Marzano Transplanted into Kratky, Week 1

Fingers crossed that the seedlings survive now. I’ve only transplanted once or twice, and they have all survived, but taken a bit of stress in the process.

Have you transplanted tomatoes, or any other plants? Do you have any tips to share?

Growing Nero Toscana Kale in Kratky Hydroponics – Update: Week 1

It’s been one week since I planted my kale seeds in my Kratky hydroponic container, and its time to see how they have grown! The variety is Nero Toscana.

Nero Toscana Kale, Image Courtesy of Botanical Interets
Nero Toscana Kale, Image Courtesy of Botanical Interets

Please excuse the dusty lid; whilst my plants are growing inside, we still get quite a lot of dust from dust storms, and just general air. I also noticed that my paint hadn’t fully cured and was slightly sticky, thus catching all those little dust particles.

Kale Grown In Kratky Container, Week 1
Kale Grown In Kratky Container, Week 1

4 out of 5 of my Nero Toscana kale plants sprouted, and have grown enough to remove the little grow dome (salvaged from some used Aerogarden Bounty pods).

Kale Grown In Kratky Container, Week 1
Kale Grown In Kratky Container, Week 1

One net cup did not sprout anything at all, even though I planted three seeds in each cup. In itself I would consider this just bad luck, but in the Swiss Chard bucket beside this one the same outer cup didn’t grow there either.

Kale Grown In Kratky Container, Week 1
Kale Grown In Kratky Container, Week 1

The rock wool medium is wet, so the seed should be getting enough moisture to germinate. Perhaps there is too little light reaching these outer cups? I have switched the outer cup with an inner cup in the hopes that it gets the light needed for a slightly later blooming, but so far nothing.

Do you have any idea why just one cup might not germinate? Please share your ideas in the comments below.

Growing Swiss Chard in Kratky Hydroponics – Update: Week 1

Bright Lights Swiss Chard, Image Courtesy of Botanical Interests
Bright Lights Swiss Chard, Image Courtesy of Botanical Interests

It’s been one week since I planted my Swiss Chard seeds in my Kratky hydroponic container, and its time to see how they have grown! The variety is Bright Lights.

Swiss Chard Grown In Kratky Container, Week 1
Swiss Chard Grown In Kratky Container, Week 1

Please excuse the dusty lid; whilst my plants are growing inside, we still get quite a lot of dust from dust storms, and just general air. I also noticed that my paint hadn’t fully cured and was slightly sticky, thus catching all those little dust particles.

Swiss Chard Grown In Kratky Container, Week 1
Swiss Chard Grown In Kratky Container, Week 1

4 out of 5 of my Bright Lights Swiss Chard plants sprouted, and have grown enough to remove the little grow dome (salvaged from some used Aerogarden Bounty pods).

Swiss Chard Grown In Kratky Container, Week 1
Swiss Chard Grown In Kratky Container, Week 1

One net cup did not sprout anything at all, even though I planted three seeds in each cup. In itself I would consider this just bad luck, but in the kale bucket beside this one the same outer cup didn’t grow there either.

The rock wool medium is wet, so the seed should be getting enough moisture to germinate. Perhaps there is too little light reaching these outer cups? I have switched the outer cup with an inner cup in the hopes that it gets the light needed for a slightly later blooming, but so far nothing.

Do you have any idea why just one cup might not germinate? Please share your ideas in the comments below.

Seed Germination Temperatures

A bit over a week ago I planted some spinach seeds, and sadly they didn’t germinate. I began a bit of research as to why. Despite my spinach varieties being hardy to warm weather, they still need cooler soil to germinate! The adult growth stage can handle warmer temperatures but the seedlings are too vulnerable still.

I began to wonder what I could grow with my current temperatures. It’ll also be handy to know the minimum temperatures for when the seasons change.

Whilst my plants aren’t being planted in soil, instead hydroponic is usually planted in rock wool or peat moss, the germination temperature should theoretically remain the same.

Optimal °FOptimal °C
Amaranth, Red Leaf68-7520-24
Basil, Purple Petra65–8518-30
Basil, Genovese70 – 9021 – 32
Broccoli45 -85 7-29
Cilantro55-7013-21
Cucumber, Lemon70–9021-32
Kale, Nero Toscana 65–8518-30
Lettuce, Little Gem (Romaine)40-755 – 24
Lettuce, New Red Fire60–7016-21
Lettuce, Red Sails60–7016-21
Lettuce, Red Salad Bowl50-7210-22
Pepper, Cayenne65-9518-35
Pepper, Jalapeño 65-9518-35
Spinach, Matador50–7510-24
Spinach, Lavewa50–7510-24
Spring Onion68-7720-25
Swiss Chard, Bright Lights75–9024-32
Swiss Chard, Lyon50 – 7510 – 24
Taisai, Pak Choy50- 8010 – 27
Tomato, Marmande VR60 – 7015 – 20
Tomato (Cherry), Supersweet 100 FT75 -9021-32
Tomato, Sam Marzano70–9021-32

I measured my Aerogarden water and it’s hitting a maximum of 85°F (30°C)! No wonder my spinach never sprouted, its ideal temperature is 50-75°F (10-24°C). Its just way too hot for them.

I’ll have to wait a while for the weather to get a bit cooler before I can sprout spinach; in the meantime I can try growing some Bright Lights Swiss Chard and Nero Toscana Kale.

How much space do I need between hydroponic net cups?

Plants often have a recommended spacing when growing in soil, and I was curious if they had to same requirements when growing hydroponically. I’d like to grow several plants at once, maximising the shelf space that I have.

It would be great to have several lettuce growing in one container. I plan to harvest the larger leaves as they become available, leaving the plant to continue growing, rather than harvest the entire plant in one session.

Why Plants Need To Be Spaced

If lettuce are grown too close to each other

they will likely receive less than the required amount of light… they can also receive less air/CO2 than they require for proper growth.

We Grow Hydro

It seems that adequate airflow is also required to help reduce mildew and other diseases. And plants need to meet a certain level of light in order to grow; I learnt this the hard way in the post Do I Need Grow Lights?

What Spacing Is Ideal

There doesn’t seem to be a consensus of how close net cups can be before lettuce growth becomes detrimental; measured centre to centre of each cup. Part of the problem lies in what plant is being grown, as well as when and how often it is harvested. For example a larger plant (like a tomato) will definitely need more space to grow than a smaller plant (like a lettuce). Secondly, many assume you would harvest an entire mature plant in one session (such as commercial growers), whereas some people prefer continual harvesting where they only take a few outer leaves at a time and let the plant continue growing.

WeGrowHydro claim that plants should be spaced a minimum of 18″ apart (45cm) for plants less than 3 feet in height! For me that’s a total of 1 plant per shelf! If they had to point out plants less than 3ft, it makes me wonder if the plants they are growing are much larger than lettuce…

SFGate Home Guides suggests that spacing should be 8-12″ (20-30cm).

Bernard Kratky himself, the founder of the Kratky hydroponic method, wrote in a paper:

“Two common planting densities for lettuce are 1.5 and 1.9 plants per square foot”.

Bernard Kratky

That calculates to one lettuce every 6-8″ (12-20cm) for commercial growth. Again, this assumes that the entire plant is harvested in one session.

Steemit claims that lettuce should be at least 6 to 8″ (12-20cm) apart. However their article looks like it’s written for commercial growers – or large setups where you might harvest entire lettuce in one session.

Photos on Steemit Website - Their Greenhouse
Photos on Steemit Website – Their Greenhouse

Christian Haschek‘s blog shows a vertical hydroponic setup where he spaces the cups by 4″ (10cm). This is the first case I have found where the hydroponic setup is aimed towards home-growers rather than commercial, so it could be assumed that he harvested individual leaves or perhaps before the plants became fully mature.

Christain Haschek's Vertical Hydro Setup
Christain Haschek’s Vertical Hydro Setup

Even my Aerogarden Bounty has spacing of only 4″ (10cm) between each pot. This system is definitely aimed at the home grower, encouraging continual harvesting of the plants.

What Spacing Do You Use?

I’m curious to know what spacing you used? Please share with us what plants you have grown and what spacing you used between net pots (centre to centre).

The Best Nutrients and Ratios for Hydroponics?

Plants can’t survive from water alone; they need nutrients as well. In traditional growing, the plants will often get what they need from the soil (and even then you often still add fertilisers). But hydroponics removes the soil. Instead you need to use hydroponic solutions with the correct ratios of nutrients; too much or too little and your plants will suffer and potentially die!

General Hydroponics Nutrient Combo Pack
General Hydroponics Nutrient Combo Pack

I use General Hydroponics Combo Ferilizer pack for my hydroponics. In fact a lot of people recommend this brand. This brand has split the different nutrients a plant needs into different bottles. Plants need different amounts of various nutrients depending upon their growth stages; and the General Hydroponics Combo pack comes in three bottles that each contain different concentrations, allowing you to target each growth stage and get maximum growth and yields!

The Ratios

Mix the following amounts of nutrients into one gallon, or 3790ml, of water. I recommend filtered water to help reduce debris and other microbes from entering your hydroponic systems.

All nutrient measurements are taken in teaspoons.

GroMicroBloom
Seeds & Cuttings1/41/41/4
Vegetative Growth321
Late Vegetative to Pre-Bloom222
Bloom to Fruiting123

I use the vegetative ratios of 3-2-1 for my Kratky lettuce since its main goal is to grow vegetation and leaves. Ideally I don’t want my lettuce to bolt and flower as the leaves will turn bitter.

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.