Instructables

Hydroponic lettuce garden from plastic bottles (Grow bottles)

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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.

 
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Very interesting article, am going to try this very soon, thanks!
freso2 years ago
Under step 8 you mention
5 drops egg shell extract (see below)

But below you say

This is enough for 2 L of growth media, so only add half (about 1 tbsp) if you are making a 1 litre batch

Isn't this contradicting? For 1L growth media, should I use 5 drops or 1 tbsp?
Professor-Mousedude (author)  freso2 years ago
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.

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.

Sorry for the confusion
biotectable2 years ago
I'm thinking about trying this project with upcycled wine bottles. Similar to this product:


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?

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.
352270GrowBottle.gif
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.
jbrisebois2 years ago
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!

Jon
neobepmat2 years ago
Hello Professor, I'm trying to replicate your DIY Hydroponic.
1st of all, thank you for this piece of knowledge, I appreciate it.
Regarding Hydroponic for Lettuce...
How long do you keep this nutrient solution without adding nothing else?
Do you completely change the water or never?
Professor-Mousedude (author)  neobepmat2 years ago
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.

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.
missplumeau2 years ago
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.
fozzy132 years ago
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.

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.