I have no land to grow a garden, But I do have windows that get plenty of sunlight.  I wanted a compact, low maintenance way of quickly growing lettuce and other small, fast growing plants.

My goals were:

cheap: I'm not looking to spend much money on this project, so cheap is good, and free is better. After all, that's why we're doing it ourselves, right? I got pretty much all my materials from recycle bins at work or other household items. The few things you would have to buy cost less than $10, and provide enough material for many of these bottles.

It's easy: No expensive tools or equipment, no expertise, just scissors, and an "exacto knife" or other sharp pointed blade.

low maintenance. Once you set it up, it requires no watering, no fertilizing,

no electricity: There are no air or water pumps. The roots get oxygen by forming aerial roots above the surface of the water as the water level drops.

The materials are easy to find: anybody, anywhere can find the materials for this project. You can use almost any kind of plastic bottle with relatively smooth straight sides, from 24 oz up to 2 litre bottles and beyond. Water bottles, Soda bottles, fruit smoothie bottles, square bottles, round bottles, whatever. The growth media is made from easy to find products, for $5 you can buy enough to fill hundreds of these bottles. I've also been experimenting with using water from a fish tank as fertlizer, with good results so far.

It works: So far it's been working great. the plants are healthy and are growing quickly. The roots look healthy and are not rotting or showing signs of lack of oxygen. The leaves are nice and green and show no signs of nutrient deficiencies. A hydroponic system should work as well or better than a soil based system, otherwise, what's the point.

It's compact. the smaller bottles take up about 3 inches of a windowsill, and the larger (2 liter) bottles take up only 5 inches, so you can fit several in a window. You can also hang bottles to use the vertical space of the window. I'm still working on an easy way to hang them. When I get it right I'll post that part. too.

Step 1: Materials Needed

Materials needed

A plastic bottle: Any size larger than 23 oz. Large 2L bottles work very well, but smaller bottle work fine for small plants like lettuce. you're only growing these for about a month, so it doesn't need to be huge. Also, the sides must be fairly straight and smooth, especially near the "shoulder". Bottles with lots of grooves or ridges don't work well. I've used round bottles and square bottles, they both work fine. Bottles with slightly thicker and stiffer plastic work quite well.

A Shower Scrunchie: one of those plastic mesh shower sponge thingies. they consist of about 10 feet of mesh, which is actually a hollow tube of mesh folded and tied into a compact shape. One of these is enough mesh to make dozens of grow bottles.

Scissors: nothing fancy.

a knife: a very sharp utility knife or exacto knife with a sharp tip.

aluminum foil: To protect the roots from direct sunlight. I grew one plant for a few weeks without the foil, and it didn't seem to really harm the roots, but they did grow away from the sun, rather than growing straight down like the others. You are also likely to develop a problem with algae if the roots and liquid media is exposed to direct sunlight, and this will quickly consume the nutrients and foul the water. You could probably use something that looks nicer, if that's important to you.

(update: after a few more weeks, the plants without foil around the water reservoir did develop serious algae problems, and were noticeably smaller than the ones that were covered)

tape: regular clear office tape.

Seeds: I'm using lettuce, because it's fast growing, and has a shallow, fibrous root system. Bibb lettuce apparently works very well, although I'm using a red leaf lettuce. Try other things, and let me know how they work. larger plants would obviously require larger bottles. A packet of lettuce seeds contains hundreds of seeds, so you don't need to buy a lot, and share the extras.

Growth media: You could buy ready made hydroponic growth media, but it's expensive. You can easily make growth media from store bought fertilizer and epsom salts, with home made egg shell extract for calcium and micro-nutrients.  A small box of fertilizer costs about $3, and box of epsom salts is about 99 cents. You only use a tiny bit of each, so even the smallest box of fertilizer can make enough media for hundreds of grow bottles. Egg shells are basically free, assuming you eat eggs once in a while. A single egg shell dissolved in lemon juice will be enough micronutrients for several bottles.
<p>Wow this is really amazing I am surely going to do this </p>
<p>Hello,this is a great job and I want to do it too but I have a problem about the fertilizer you use....can I atleast know which type of fertilizer is it and the mineral composition ? I want to buy a brand that have the nearest composition of your and again,really great job! ;)</p>
I just used regular miracle gro. I had a little sample size package of it. <br>
<p>Really tnx man,times 2 days and I will try my solution for the plants and set up bottles and all.Anyway,I am a bit worried about the solution...I think that some micronutrient will miss,like iron...But is better to try first and tnx again !</p>
I wonder if adding a series of small aerator stones with a single large air pump and put a couple guppies or other small fish in the bottom would add a natural extra oxygen and a sustainable source of food. Air pump won't hardly use any electricity.
That might work! It would have to be a very small fish, and very tolerant of poor water quality. And you would want to feed just the minimum amount of food. <br>try it out!
<p>I am definitely going to try this...it's a lot simpler and easier to follow than a lot of other pages I've seen. Thanks. </p><p>I'm thinking instead of wrapping in foil, I'm going to try painting the bottom part of the bottles on the outside in a dark color. </p>
<p>I will be doing a similar project with my homeschooled children, as well as a compare and contrast with plants grown by other means. I'm curious...you mentioned doing more observations on plants grown using fish water. Did they have the same results that you mentioned (less growth)? Thank you for your very detailed, informative post. We're looking forward to our project, based on yours! </p>
<p>with regards to step 8? will it be ok if i use the soil fert directly?</p>
<p>It might work OK, but most regular fertilizers don't have much calcium </p>
<p>Ok... Calcium.. ill try to save egg shells den. so... powederize the shell...? and add to the liquid fertilizer.. I'll try it. Thanks :)</p>
Very interesting article, am going to try this very soon, thanks!
Under step 8 you mention <br>5 drops egg shell extract (see below) <br> <br>But below you say <br> <br>This is enough for 2 L of growth media, so only add half (about 1 tbsp) if you are making a 1 litre batch <br> <br>Isn't this contradicting? For 1L growth media, should I use 5 drops or 1 tbsp?
5 drops is the revised (approximately half strength) recipe, which I found works just as well. So you can make a full strength batch usingn a tbsp, then dilute it in half with water. <br> <br>Also, I have very hard water with lots of calcium already in it, so I reduced the amount of eggshell extract. I was getting calcium deposits on the inside of the bottle! If you don't have hard water, or are using very pure water, then you should probably go with the full 1 tsp/litre. <br> <br>Sorry for the confusion
I'm thinking about trying this project with upcycled wine bottles. Similar to this product: <br> <br> <br>However, I think your method of growing seems a little better than this product. Do you think if I were to use a dark green wine bottle it would provide enough of a block to UV light to prevent algae growth? <br> <br>Also, I noticed that the wine bottle has no air hole. Do you think this omission would be important enough to really hurt the plant growth.
The main purpose of the air hole is to allow new water to be easily added without taking everything apart. It also provides oxygen for the roots, they need to be able to breathe.
Use GREEN pop bottles and you'll have zero algae growth.
I saw your instructable a few months ago and decided to try it. I decided on green beans. It has worked better than I have ever imagined! Great job, and Thank you! We have been getting almost 2 beans every other day and about 25 total so far! This was a great learning tool for my 3 year old daughter! She loves to run over there every morning to see how big the beans are! So again, I thank you! <br> <br>Jon
Hello Professor, I'm trying to replicate your DIY Hydroponic.<br>1st of all, thank you for this piece of knowledge, I appreciate it.<br>Regarding Hydroponic for Lettuce...<br>How long do you keep this nutrient solution without adding nothing else?<br>Do you completely change the water or never?<br>
The more protected from light the solution is, the longer it can go without being changed. The main problem is algae growth. If sunlight shines on the solution you will quickly end up with a bottle of green goo. If the bottle is wrapped in foil all the way to the top, and the funnel is lined with foil, then you shouldn't have much of a problem.<br><br>Keep an eye on the plants, and check the roots often. if they show signs of yellowing or other stress, then change the solution. Also be sure the roots are never left high and dry. the plants use quite a lot of water when they get larger, so you may have to top the water level off daily, but you can just add tap water, no need to top off with new solution unless you completely replace the solution.
How much sun exposure? I have a window facing east/south east that get morning and early afternoon full sun and and another facing west/southwest that get afternoon noon till sunset full sun. Thanks for sharing your simple and clever project!
The more sun the better. These are in a west facing window, so they get sun from about noon until sunset.
This is great! This biggest turn-off for me and starting hydroponics is definitely the cost. Good work!
This is a great project! I love that you reused so many items for it. :)
Thanks, It's my first instructable, but probably not the last. Always nice to get complements from someone else with a rodent themed nickname. <br><br>Reuse and recycling was a main goal of the design. There a lot of other great bottle hydroponics projects, but I wanted to develop a cheap and easy growth media recipe, and improve the aeration of the roots.

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Bio: I'm a biologist, and a professional geek. I can't believe they pay me to do science!
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