Growing Lettuce with Kratky Hydroponics. Update – Week 3!

Three weeks ago we germinated some deer tongue lettuce in our Aerogarden Bounty – who doesn’t love lettuce? About two weeks later, I needed the Aerogarden to start some more seedlings. So I transplanted from the Aerogarden to a kratky container.

At first they were really unhappy, and I expected them to die. Not only was there the stress of transplanting, but I moved them from Jiffy 36mm Peat Pellets to cloning collars! Double damage to the life bar (video gamer speak).

Day One Transplant of Lettuce
Day One Transplant of Lettuce

Don’t they just look sad?? Well, thankfully they have perked up so much since then!

Week 3 Deer Tongue Kratky Lettuce
Week 3 Deer Tongue Kratky Lettuce

For some reason one of the lettuces recovered faster than the others, and this gave him a significant growth spurt. The front lettuce are all slightly larger than the ones at the back and I am unsure why; they should be getting about the same amount of light, temperature and nutrients.

Week 3 Deer Tongue Kratky Lettuce
Week 3 Deer Tongue Kratky Lettuce

Even the mason jar lettuce has significantly picked up after nearly dying from a lack of light!

Week 3 Deer Tongue Kratky Lettuce
Week 3 Deer Tongue Kratky Lettuce

I’m curious, what plants have you transplanted successfully? Do you regularly start seeds elsewhere and then transplant, or do you start seeds in their final (and only) growing location?

Can You Germinate Seeds In Cloning Collars – The Experiment

I’ve seen some Youtube videos and articles where they grow their hydroponic plants in pool noodles. They claim to get high harvest yields, and they regularly talk about the benefit of being able to reuse the pool noodles.

Plastic Pool Noodles
Plastic Pool Noodles

I was concerned about the safety of using pool noodles; as we know plastic can leach chemicals and micro-particles into the water and plants (and eventually you). This process is often sped up with exposure to high temperatures… and Kuwait set a world record for the highest temperature in the world reaching 52.2°c (126°f) in the shadows and 63°c (126°f) in the direct sun!

Instead we bought a cloning collars and net cup pack as these have been specifically designed to grow plants and food.

After I bought the collars I realised that there weren’t many people online saying you could start seeds in the collars; they are generally used for transplanting cuttings from older plants.

I decided to do an experiment on whether I could grow seedlings in cloning collars.

I’m starting this experiment on Aug 7, 2019.

The Seed Added To The Cloning Collar
The Seed Added To The Cloning Collar

I sterilised the cloning collar and the container with hot water.

If you look closely you can see the Lemon Cucumber seed in the middle of the cloning collar. I’ve inserted it so its very close to the bottom of the collar (I’m holding it upside down), but far enough in that it hopefully doesn’t fall out.

My Test Grow Chamber
My Test Grow Chamber

Apparently seedlings will grow best when exposed to high levels of humidity. I wanted to make sure that my seedling could get as much light as possible at the same time. So I found this old Ikea air-tight plastic container. It has a de-gas spout which I have kept closed.

Fingers crossed that this container won’t grow algae since my nutrient rich water is also exposed to light.

Transplanting From An Aerogarden To a Kratky Bucket

I needed to make space in my Aerogarden Bounty to plant some new seedlings, so rather than kill the entire crop I decided to try and save them by transplanting to my Kratky container.

Transplanting from the Aerogarden Bounty can be quite difficult; the fine roots of the hydroponic lettuce wrap around the plastic support bars, and unfortunately rip easily when removing from the cups.

I was also using the Jiffy 36mm Peat Pellets which have a very fine mesh wrapping, and removing this mesh would rip any remaining small roots. Normally you wouldn’t have to remove the mesh, or even seperate the lettuce from the peat pellets, however I wanted to try out my new cloning collars.

By the time that the lettuce was removed from the Aerogarden Bounty container and the Jiffy had been removed and all peat washed off, only the major roots of the lettuce were left. The poor plants were definitely going to go into shock, and may not survive at all.

Day One

Day One of Lettuce Transplant
Day One of Lettuce Transplant

Ouch. It doesn’t look like the lettuce is going to survive; I think I pulled off too many roots and shocked the plants way too much.

Since the roots are so short now I have the water level half way up the net cups. This leaves very little space for any air roots to grow, especially given the size of the lettuce already.

Day Two

Day Two of Lettuce Transplant
Day Two of Lettuce Transplate

They still look bad, but thankfully at close inspection they seem to be recovering slowly. It’s hard to tell in the photo, but they are a little perkier than on Day One. You can see the centre back lettuce sticking one of his leaves straight up now, compared to yesterday’s droop.

The lettuce at the front right seems to be the last to start recovering; none of his leaves are currently stiffening up again.

Day Three

Day Three of Lettuce Transplant
Day Three of Lettuce Transplant

I pulled off some of the biggest leaves that did not look to be recovering (and ate them); I want the plant focusing on fresh growth of roots and new healthy leaves rather than saving pre-existing leaves.

The lettuce are definitely recovering by this point; the centres are much more perky and green.

Generally you shouldn’t expose the Kratky nutrient solution and roots to light, but I couldn’t resist a quick look to see how the roots were recovering.

Day Three Roots on Lettuce Transplant
Day Three Roots on Lettuce Transplant

The roots are all slightly brownish, with several potential reasons: firstly the nutrient solution is a brownish tinge and could be discolouring the roots, or secondly there could be root rot developing. If the roots turn dark brown or black and become slimy then I have root rot.

The lettuce that seems to be recovering the most are on the left side of the container, which is reflected in their root development; these two lettuce have already grown roots beyond their net cups! Surprising how fast they grow!

You can’t see it in the photo, and its hard to see in person even, but some of the roots have started to develop a white fuzz. Here is an example of a reddit user with the white fuzz on their roots. This is not mold and is actually a sign the plant is “healthy” (or in this case recovering) as it helps with nutrient absorption. The roots are expanding their surface area and will either develop longer roots from these points, or remain fuzzy.

I’ll keep an eye on the lettuce and post an update in a few days. Fingers crossed they will fully recover. Until then, have you had any transplant success or failures?

Growing San Marzano Tomatoes in Kratky Hydroponics – Update: Week 1

I’ve heard a lot of people online say that they have had decent success with growing tomatoes in hydroponics, so I wanted to test just how easy it was myself.

This is the growth after 1 week, planted on 1st August 2019:

I planted some seeds into Jiffy 36mm Peat Pellets. Unfortunately just after planting we discovered that our grow light was faulty! Rather than waste the seed and peat pellet, I decided I would just start a new session in my Aerogarden Bounty. Once my replacement grow light arrives I will remove from the peat moss and transplant into a cloning collar.

They began to emerge from the pellet only three days ago, with the smallest white to very pale green sprout showing. They are growing so fast as they reach for the light!

Tomato Seedling Week 1
Tomato Seedling Week 1

Strange enough the second seedling grew two sprouts. I am pretty sure I only placed one seed in each pellet.

It looks like the two sprouts merge into one stem close the soil. I don’t want to disturb the peat moss yet. If there is more than one seedling in the pot I can seperate them when I transplant; hopefully my new light will arrive soon.

Tomato Seedling Week 1
Tomato Seedling Week 1 – Look at his little seed hat!

Have you grown hydroponic tomatoes? I would love to know how well they grew for you.

What Plastic Should I use for Hydroponics?

Hydroponic plants are always grown in some form of container; in essence they are a container with water, and sometimes fancy tools like pumps. A lot of people grow small produce like lettuce in mason jars using the Kratky method, but most commonly plants are grown in plastic buckets, totes or buckets.

Keep It Food Safe

It needs to be food-safe, and yes this is important. Many people will use plastic containers but they are often unaware that overtime plastic degrades and can leach micro-particles and chemicals into the water, all of which will be absorbed by your plants as they grow (and subsequently eaten by you).

Plastic leaching these dangerous chemicals are even worse if you live in a hot environment, and if the plastic is exposed to heat at any time (such as at the store before you bought it). Furthermore, some plastics will react if exposed to certain products, especially if they are too alkaline or too acidic.

The Risks

The wrong chemicals exposure can be dangerous. BPA and some phthalates are endocrine disruptors, mimicking natural hormones and causing a cascading number of different health problems such as infertility, obesity, breast cancer, prostate cancer, reproductive development, heart disease, diabetes… and more.

Honestly, just don’t risk it.

What Plastic Can I Use?

Find a container using Polyethylene Terephthalate (PET). Apparently PET is “biologically inert if ingested, is dermally safe during handling, and is not a hazard if inhaled“. PET wont degrade when in contact with food or beverages.

Polypropylene (PP) is another common used plastic; found in many food storage containers and microwave safe containers. This plastic can be heated safely, and it doesn’t react to liquids, acidity, or alkaline foods.

High-Density Polyethylene (HDPE) is often found as dairy containers (milk or butter), cereal box liners, and large food buckets. It doesn’t absorb liquid, and futhermore doesn’t leach chemicals into their contents.

What Plastics Should I Avoid

Recycled Plastics Any plastic that is recycled may not be food safe. I would avoid any recycled plastics for hydroponics.

A quote from the FDA describing the risks of recycled plastics:

1) that contaminants from the post consumer material may appear in the final food-contact product made from the recycled material, 2) that recycled post-consumer material not regulated for food-contact use may be incorporated into food-contact packaging, and 3) that adjuvants in the recycled plastic may not comply with the regulations for food-contact use.

PVC. Did I just say that right? Yep. A lot of DIY hydroponics use PVC pipes to store and run their hydroponic solutions, and even grow their plants. In it’s rigid form PVC is probably safe, however in its flexible it could be dangerous. To make it soft a plasticiser is added, often up to 40%! According to Choice Australia recent studies have raised concerns about the health risks.

Polycarbonate should be used with caution. Whilst a lot of food storage containers are made with this plastic, recent studies have suggested that polycarbonate can release bisphenol A (BPA) which can cause serious health problems.

Further information on types of plastic (and their numbering system) can be found here:

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!

Do I need grow lights? Update – Week 2

Read about the first week of growth in the post Do I Need Grow Lights? Update – Week 1.

It’s been two weeks since I transplanted my Deer Tongue Lettuce seedlings from the Aerogarden Bounty to my makeshift Kratky containers. The seeds were started in the Aerogarden on 17th July, so they are now only 18 days old. I started this experiment to test how the lettuce would grow under the light conditions of different rooms; my laundry, my pantry and my kitchen.

In the post Do I Need Grow Lights?, started just after transplanting my lettuce, I actually measured my light more scientifically. Spoiler alert, it was then that I discovered that my rooms were below the ideal levels for plant growth and that I would in fact need to purchase some grow lights.

Since my grow lights haven’t yet arrived, I decided to just let the lettuce sit in those rooms. Sometimes the amount of light to maintain is much less than the amount of light needed to create fresh growth. Even if the plants don’t get enough light in those rooms to actively grow, they may be acceptable places to store plants (if necessary) for a few days before I can completely harvest them.

Week 2 Kratky Lettuce Compared
From left to right: pantry, laundry, kitchen.

The lettuce didn’t really grow during this last week; the lettuce in the pantry being the exception. Compare this to last week:

Week 1 Kratky Lettuce Compared
Week 1 Kratky Lettuce Compared. Left to right: pantry, laundry and kitchen.

The pantry lettuce definitely grew a bit between week 1 and 2, although not as apparent in the photos. The leaves became wider and greener.

The laundry lettuce stayed mostly the same size. Its leaves did start to droop and curl slightly. This area is now being converted into a more permanent grow area including a couple nice grow lights!

The kitchen lettuce had started to die due to the lack of light. It struggled the most, which reflects our light readings that we got in the post Do I Need A Grow Light? The light was just so minimal in this area that the plant couldn’t even maintain it’s size, let alone grow! This area may be okay to store a plant in for a couple days, especially if the plant is destined to be eaten (why harvest all at once if I can pick the leaves off fresh over a couple days), but I won’t be trying to grow anymore in this area.

Despite hearing success stories online, I was a little skeptical if this method would actually work. But…

Photo of Lettuce Roots Growing
Photo of Lettuce Roots Growing

Seeing is believing! Roots emerged from the bottom of the DIY net cup, and quite proficiently. I was honestly quite surprised by the amount of root growth – only two weeks ago there were no roots at all touching the inside of the DIY net cup!

The End Of An Era

This experiment, the total of two grueling weeks, is now over. I’m moving what’s left of the lettuce to live under my new grow light; it’s now an experiment to see if I can get it to survive and recover.

How Long Should My Grow Lights Be On For Hydroponics?

I need sunlight daily to get Vitamin D, but if I get too much at once I will get sunburnt and potentially cancer! It’s better to get an optimal amount of light (such as when wearing sunscreen) over a couple hours.

Daily Light Integral

Just like us plants have optimal light brightness levels, as we calculated in the post How Bright Should My Hydroponics Light Be? Different stages of plant growth will require more or less light strength and lighting time. A seedling might need very low light strength over a short time (its a baby so it needs to sleep a lot), whereas a fruiting plant will need all the extra energy it can get through higher light strength and longer lighting times.

The best way to tell if your plants are receiving enough light to grow is by measuring the Daily Light Integral, or DLI. The DLI is a measure to of how many moles/m2/day our plants get. Notice how we will be converting from umols, or micromoles, to their higher unit. This is a bit like grams to kilograms, or ounces to pounds.

If you already have the PPFD or umols/s/m2, such as whats advertised when buying lights online, then you can use a simple online calculator to calculate your required number of hours to the DLI. If you don’t know how many umols/s/m2 your room or light is, check out the post How Bright Should My Lights Be?

According to Wikipedia having the correct DLI can help your plant leaves to grow thicker, increase flower and fruit yields, have more and stronger roots, as well as have more leaves and heavier biomass (they produce more leaves and less stems and stalks).

According to Specmeters:

Lettuce (butterhead)14-16
Tomatoes (seedlings) 6-8


I found a really great article from the Department of Horticulture and Crop Science: this PDF covers a huge variety of plants, and the recommended lighting and hours lit for each of the growth stages, and what level nutrient solution is ideal.


# Light HoursLight Intensity


# Light HoursLight Intensity
Vegative12-20 250-450
Flowering<12 250-450
Fruiting12-20 250-450


# Light HoursLight Intensity
Flowering12-20 450-700
Fruiting12-20 450-700

My kitchen had on average 250 LUX from the window – it’s a dark room considering direct sunlight has 900-2000umols. Using the Environmental Growth Chambers calculator, 250 LUX converts to 4.75 umols/s/m2.

If I was growing tomato seedlings, I would need to divide my result (4.75) by the number of hours to reach the ideal DLI of 8. In this case I would need my plants to receive approximately 1.5 hours of sunlight per day. An adult tomato needs 22-30DLI, so as it grows I would slowly increase the number of hours its exposed to sunlight to 6 hours a day.

But I will be using my grow light on my tomatoes. This light produces 565umol/s/m2. Using the same calculator I can tell that for seedlings I only need to expose them to 4 hours a day of light, whilst adult plants would need ideally 14 hours a day.

Quick Reference Chart

This PDF has a wonderful table of many, many, plants that compares different life stages, the strength of light recommended, and how many hours those plants require at such a stage.

Where To From Here?

Beginners Guide To Hydroponic Lighting has a list of all our posts on lighting, written to help a beginner learn the basics and get started right through to more advanced topics.

How Bright Should My Hydroponics Light Be? is the previous post in this series. It explores how much light certain plants needs to grow. I also show you how to convert to the more common used light measurement value umols or PPF, which many grow lights use. Understanding these values, and how they get them, will help you make an informed purchase.

Beginners Guide To Hydroponic Lighting

Wow! Learning about lights for hydroponics, or just plant growing, gets overwhelming fast. So many terms and numbers to keep track of. Here’s a roundup of posts that help explain lighting, all written for an absolute beginner in mind!

Do I Need Grow Lights?

Not everyone has a PAR meter or Quantum meter; they can be expensive. So how else can you measure the light your room gets? Whilst not very accurate, this can give you an idea of how bright your rooms are; helpful in finding out if you need to invest in a grow lamp!

How Bright Should My Hydroponic Lights Be?

This post explores how much light certain plants needs to grow. I also show you how to convert to the more common used light measurement value umols/m2/s or PPF, which many grow lights use. Understanding these values, and how they get them, will help you make an informed purchase.

How Long Should My Grow Lights Be On For Hydroponics?

So you know how bright your light should be, but how long should it shine? Plants need time to sleep and rest too, just like you. This post explores how to determine how many hours of light your plant needs (it can vary a little depending upon how bright your light is).

Grow light heights? Is it too close or too far away? – coming soon

Lights have different intensities, depending upon how far away you are to them. That little candle might not put off much light or heat from across the room, but up close you can still get burnt! This post will be exploring PAR, PPF and PPFD.

Waveforms and Colors – coming soon

Humans can see white light, and our eyes prefer it. But plants actually prefer different colors, most often reds and blues. This post explores the colors that lamps output – usually referred to in waveforms.

If you want a more advanced list of lighting resources, check out the post SAG’s plant lighting guide linked together.

Where to buy organic seeds in Kuwait

Don’t want to read? Here’s a quick list of links:

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 the 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.

They delivered within 48 hours. We have been very happy with the brand of seeds that Sustainable Organic Q8 sells; which is Botanical Interest. They contain a lot of seeds in the pack, and they so far have a really high germination rate (for me its 100%).

Update – 24th August 2019: We found another Kuwait website selling seeds called My Organic World, though the website is all in Arabic (use Chrome web browser for auto-translate to browse in English). We bought from them, and they delivered within 24 hours! Unfortunately they sold brands Sperli and Kiepenkerl which consensus online says they can be quite expensive compared to competitors. One of the packs we bought only had 5 seeds in it! Not a reflection of My Organic World, but the seed producers themselves.

Update – 31st August 2019: Another Kuwaiti website selling seeds called PlantNMore. though the website is all in Arabic (use Chrome web browser for auto-translate to browse in English). I haven’t bought from this company yet.

Do you know anywhere else in Kuwait to buy seeds? Please let us know in the comments.