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." 

Step 1: 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

Hi Diane,<br>Thanks for a very informative post.<br>I now realise the mistakes i have been making with my hydroponic experiments.I still have some questions.<br>1.What difference will it make if we use any other nutrient formula say <br>9-9-9 NPK or any other.<br>2.How does the lettuce perform in open? Do we need to cover and isolate the growing containers/ area with a plastic sheet or net.<br>3.Can we plant the seeds directly in the net pot or should we plant the seedlings.<br>4.If we start with seeds why do we need to keep some empty space in the container. Why not fill it up completely till it touches the bottom of the net pot.<br>5 How can we grow lettuce if the outside ambient temperature is above 40&deg;C.<br>Thanks<br>Arun
<p>Hi, sorry for the delayed response... For the nutrient, a 9-9-9 NPK is a base formula that you augment based on what you are growing. You should find nutrients specific to vegetables and/or fruit and you should not compromise quality. I grow my lettuce outside, under our house eaves, you'll want to prevent rain water from diluting your nutrient solution. I plant my seed directly in the net pot all the time. You should absolutely fill your container with nutrient solution to the net pot so that the moisture and nutrient reach the seed. Only when refilling do you fill it up part way so that the roots can take up oxygen and not drown. I'm not sure how the lettuce will do at that temperature, but my guess is that it will grow more like a vine than a tight cluster (still edible) and you will have to refill the nutrient more often. One more thing... I've changed my growing medium to cinder and am much happier with the results... No algae!</p>
Thanks Diane,<br>I will keep in mind your advise while experimenting.<br>Pls suggest<br>How to find which nutrients are specific to different crops.<br>PLS suggest nutrient for<br>Lettuce<br>Cucumber <br>Tomato <br>Spinach<br>Coriander<br>Can I buy say NPK 20 20 20 And then modify to suit the specific type.<br>Thanks
<p>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!</p>
<p>You can totally do this indoors!</p>
<p>Most lettuce types do not do well over about 75 degrees and can tolerate temperatures as low as 45 degrees, so a greenhouse might be an option for you if the night time temps in the greenhouse do not drop too low. I live in Southern California and have trouble growing lettuce because sometimes the temperatures are too high and the plant bolts quickly. A cooler area of California with a greenhouse seems ideal to me. Some types of lettuce like romaine can tolerate more heat but in my opinion its always a much tastier crop if you can keep the temperatures in the 70's. Good Luck!</p>
<p>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?</p>
<p>The ratio I use is one gallon of nutrient water per head of lettuce--usually one month to six weeks. You can just start over with new seed once the water has been used up or you can refill half way if the plant has more to offer.</p>
<p>You would refill the res with more water nutrient mix. This is a non-electric, non-circulating system. All you do is add nutrient mix, plant and grow.</p>
<p>I've done great in 18 gal totes as well with tomatoes, cucumbers, eggplant, and zucchini. It really is hands off and fun to see how fast it grows. We're moving to a bigger place with a small yard so I'm very excited to get my kratky up and running again with more variety. I want to try a strawberry plant.</p>
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?<br>thanks
<p>Awesome Instructable! I'm hoping to use it in the future to make a system of my own. Thanks for posting.<br><br>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.</p>
<p>Hi. a friend of mine has showed this post to me and asked me to give you some guidance regarding a statement you wrote.</p><p>&quot;At first I was worried because of the word &quot;Chem&quot; 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&quot;.</p><p>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 &quot;organic&quot; nutrients or what laymen call &quot;chemicals&quot;, 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 &quot;Chem&quot; 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 &quot;chemical&quot;, 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 &quot;chemicals&quot; is wrongly used in this context. There's nothing wrong in buying products with the suffix or prefix &quot;chem&quot; to them. What I and other scientist friends observed about the general public is that they tend to buy products with the word &quot;Bio&quot; in it and fear products with the word &quot;Chem&quot; 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 &quot;placebo effect&quot;. So, you shouldn't really be intimidated by &quot;Chem&quot; in any products name. It doesn't matter if a nutrient solution has &quot;extra chemicals&quot; or named &quot;chem&quot; or &quot;bio&quot; or even if it is &quot;chemically altered&quot;, 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.</p><p>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. </p>
Hi Dianne, <br> <br>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.
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!
Hi Dianne, <br> <br>i'd like to ask some newbie question regarding this method. <br>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, <br> <br>You did a great job on this project. Thank you for sharing. <br> <br>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. <br> <br>Do you have an update on the peas?
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!
Excellent project congratulations. <br> <br>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. <br> <br>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.
Hi Diane, <br>I just joined earlier today and read your interesting article. <br>It is very nice of you to take the time and effort to put that together. <br>I live in NW AR, our first frost date is the last of October, I plan on trying your method ASAP. <br>Thanks again, <br>Steve
You're right... that's a very good contribution, thank you!
you could use sand paper to rough up the surface to get the primer to stick even better
you could use sand paper to rough up the surface to get the primer to stick even better
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.
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.
This is absolutely wonderful! Thank you so much for such an excellent Instructable!
Diane, <br> 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 &quot;more expensive&quot; food wise. Useful information that may assist me with my initial setups. <br>Thank you, <br> Don
Very, very interesting projects, congratulations. <br> <br>Holes on plastics can be done with a hot wire or tube, more easily and without break the material.

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