Picture of Kratky's non-circulating hydroponics
A friend of mine, Ingrid, started growing her own lettuce mix at home using a non-circulating hydroponics system.  I was very interested in what she was doing because it requires no electricity and only a one time nutrient feed.  She sent me brief, but great, instructions and I did a little research on the Kratky method of hydroponics and decided to share what I've done.

These instructions are brought to you after six months of successful growing.  Ingrid had been growing for a year by the time I gave it a try.

I've also attached a PDF file of one of Dr. Kratky's papers outlining his method and how it works... if you want to get all "sciency." 
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Step 1: What you'll need

Picture of What you'll need
Underbed box 41 QT/39 L (approx 35" X 17" X 6") and/or 5 gallon bucket (I will be using both in these instructions)
Utility knife
Tape measure
Plastic paint primer and paint
1/2 inch x 1/2 inch elbow (optional)
Rubber grommet 3/4 inch OD x 7/16 inch ID (optional)
Clear vinyl tubing 1/2 inch OD x 3/8 inch ID (optional)
1/2 inch drill bit (optional)
2 inch hole saw
8 - 2 inch net cups per lettuce bed.
Strap to hold shape of container once it's filled with water
PH water testing kit
Hydroponic nutrient (your choice of brand)
Lettuce seeds
Place to set up your lettuce beds

This setup should come in at under $30

Step 2: Where to grow

Picture of Where to grow
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Before you begin, choose where you will keep your setup, on a table with some indirect sunlight or under house eaves is best.  Once the tub is full of water it is very difficult to move the system.  You can also grow indoors under light if you want, I don't because I live in Hawaii and we have a year round growing season that allows me to use good ol' sun light.
heavnbnd22 days ago

Okay, so I've done outside circulating Hydroponics for a few years during growing season. I live in mtns. of CA (inconsistent temps from 70 deg. down to teens) so can't do winter outdoors. What temp do these lettuces need in order to thrive? Trying to figure if I can do small greenhouse or need to do indoors. Thanks for the system, it looks great!

nah891 month ago

So basically how it differ from other hydroponic measures is that you don't change the water but just replace the plant when it runs out? Would the plants absorb all the nutrients in the water in like a month?

redwolf0076662 months ago
hello every body i am a new beginner hoping to test hydroponics. i am interested in planting hydroponic romaine lettuce. can you please clarify the precise conditions to grow this kind of lettuce.e.g: water ph, temperature, humidity, lighting....?i started my firat batch indoor and my sooo tiny seedlings died after they have stopped growing for a while. any ideas?
djduncman3 months ago

Awesome Instructable! I'm hoping to use it in the future to make a system of my own. Thanks for posting.

Lots of plastics are problematic when drilling holes in them. One trick I use is to find a piece of metal that is the diameter of the hole I need and heat it with a torch and use it to melt the hole in the plastic. I've never had a cracking problem using this method.

Nick SeanK5 months ago

Hi. a friend of mine has showed this post to me and asked me to give you some guidance regarding a statement you wrote.

"At first I was worried because of the word "Chem" in the title, but I called the company, Hydro Gardens, and they explained that it's just the brand name and that their product is not chemically altered and it doesn't have extra chemicals or anything like that".

You shouldn't worry much about that so much. First of all, basic biology teaches us that plants take in nutrients in their atomic form. Meaning they take in the nutrients in their basic elemental state, namely N, P, K, O, Mg and so on. No matter what nutrient you feed them, whether it is the so-called "organic" nutrients or what laymen call "chemicals", they are all broken down to their simplest state. So it doesn't really matter which type you use, what matters are the contents. As for your confusion on the "Chem" in the title, you must note that every nutrient we feed our plants, no matter which brand, which type, which composition, they are ALL made of chemicals. These chemicals in that form can be harmful if taken by humans, but very beneficial to plants. We ALL take in chemicals, albeit in different forms. Whenever we say the word "chemical", laymen tend to think of hazardous and radioactive mental pictures or scientist wearing Hazmat suits. However, you must note that every single thing in this planet is made up of chemicals. Heck, water is a chemical. So perhaps what you were worried about were actually PESTICIDE or WEEDICIDE chemicals that are usually used in farming to keep away pests and parasites. The word "chemicals" is wrongly used in this context. There's nothing wrong in buying products with the suffix or prefix "chem" to them. What I and other scientist friends observed about the general public is that they tend to buy products with the word "Bio" in it and fear products with the word "Chem" on their names. Unknowingly, both products may have similar compositions and in most cases, they come from the same manufacturer. All of them have chemicals, whether harmful or not. We call this the "placebo effect". So, you shouldn't really be intimidated by "Chem" in any products name. It doesn't matter if a nutrient solution has "extra chemicals" or named "chem" or "bio" or even if it is "chemically altered", but what you need to know is that if certain chemicals IN the nutrients are beneficial/harmful to your plant. If you are thinking of the current technology or scientific advancement which is greatly distinct from the conventional usage of chemicals, you may be thinking of Biotechnology, where we use living organisms to produce or do basically everything. This field, although different from the past scientific innovations, still does use chemicals, but in a very different and special way.

Source: I'm a Scientist (Biotechnologist) by profession. Before going to the Medical and Pharmaceutical field, I used to study Agricultural Biotechnology as part of our pharmaceutical production. Also, hydroponics and aquaponics are my hobbies, aside from micropropagation (plant cell cloning), where I produce a new plant from a small amount of plant tissue in aseptic conditions.

frojasp1 year ago
Hi Dianne,

I have experienced for 9 months in a container of 22 liter 6 bushes chile is important to note that the temperature of the site or the direct sun dehydrate plants since they are consuming more water and the pH increases causing water stress to be controlled providing more water without nutrients, so other results are good.
diannemw (author) 1 year ago
Well, you could replenish the 1/2 gallon container as needed (leaving air space for the roots), but most important is that the container be able to block sunlight. Good luck!
byakkou1 year ago
Hi Dianne,

i'd like to ask some newbie question regarding this method.
i'd like to test this method of growing in recycled water bottle instead.. is it possible? when u said that 1 lettuce would need at least 1 galon of water. what would happen if i din put enough, like only half gallon?
Hi Dianne,

You did a great job on this project. Thank you for sharing.

Do you have any issues with little pests? Here in CA, I have some big green caterpillars that ate all my mint and cat nip, we also have slugs.

Do you have an update on the peas?
DaveNJ1 year ago
Nice job with this instructable. I have tried Kratky in 1 plastic coffee container and my lettuce has not done so well even after 3 weeks. I started with the nutrients touching the bottom of the net cup but the level has never gone down. I have roots 3 inches into the water. I am trying your instruction of reducing the water level so the roots get oxygen. I also plan to make a container just like you show so I can copy your example exactly. Thanks for sharing this. Look forward to more and good luck on your plants!
frojasp1 year ago
Excellent project congratulations.

I used the method of the wick that is very similar, where nutrients to the substrate by capillary rise the problem is that the fuse very easily rot and substrate must be good at holding moisture.

I will put into practice this technique in order to evaluate it, I would like to comment more on solutions in Colombia not get as easy as shown in the article.
stevewan1 year ago
Hi Diane,
I just joined earlier today and read your interesting article.
It is very nice of you to take the time and effort to put that together.
I live in NW AR, our first frost date is the last of October, I plan on trying your method ASAP.
Thanks again,
diannemw (author) 1 year ago
You're right... that's a very good contribution, thank you!
rrrmanion1 year ago
you could use sand paper to rough up the surface to get the primer to stick even better
rrrmanion1 year ago
you could use sand paper to rough up the surface to get the primer to stick even better
diy_bloke1 year ago
Interesting, but what i dont understand is what happens if the waterlevel sinks below the pots, at a moment that the plants have no roots growing out of the pots yet. It all seems to assume that evaporation and sprouting/growing are all sort of magically connected. Or did I miss something.
diannemw (author)  diy_bloke1 year ago
(removed by author or community request)
Diane, I understand the science. I was just wondering what happens if the water disappears faster than the roots follow, but I guess the plant dies then, unless one fills up the reservoir again
diannemw (author)  diy_bloke1 year ago
So, I guess my response to the point you made in your last communication is that I have never had an experience where water evaporated before the plants rooted and grew. Also, I have never had a plant die prematurely for lack of water outside of human error.
that is good to hear. maybe i worry too much
CityGirl61 year ago
My brother lives in Hawaii too is always very interested int he farmer's markets here. I'll have to send him this to see if he's ready to grow. Thanks for sharing.
WUVIE1 year ago
This is absolutely wonderful! Thank you so much for such an excellent Instructable!
padsurfdon1 year ago
I enjoyed the posting, I also live in Hawaii and am looking into growing our own vegies in the back yard. Vegetables are so expensive here, and trying to live a healthy lifestyle is really "more expensive" food wise. Useful information that may assist me with my initial setups.
Thank you,
rimar20001 year ago
Very, very interesting projects, congratulations.

Holes on plastics can be done with a hot wire or tube, more easily and without break the material.