TECH NEWS

How to Build a Greenhouse Made From Plastic Bottles

Here is a step-by-step guide on how to build a plastic bottle greenhouse, for those of you with the time and patience to collect enough empty plastic bottles to construct one.

Making this type of greenhouse is cheap, but it is also quite an undertaking in terms of labour and the time it will take. Perhaps it is best left to community organisations and schools, you might think.

Don't let that put you off. There is no reason why everyone should not have such a wonderful PET plastic construction in their yard.

a greenhouse made from plastic bottles

PET stands for Polyethylene terephthalate which is the type of plastic approved worldwide for plastic bottles intended for the drinks industry.

Advantages of a Plastic Bottle Greenhouse

• It's cheap to construct. You will need approximately 1400 empty 2 litre (40oz) plastic bottles to build a greenhouse that is 8' x 6'. Even if you don't use that many, you can collect them from neighbours, friends, hotels, bars, and restaurants in your area.
• It is self-watering. Because there are gaps at the tops of the bottles, heavy rain can certainly penetrate from where the bottles lie side-by-side. This is a huge time saver for greenhouse growers. Also, rainwater is always better for your plants than tap water.
• It raises the temperature. The temperature is raised about 10 degrees centigrade compared to the weather outside. That is a huge difference and it should certainly lengthen the growing season for many plants, no matter what climate you live in.
• It saves landfill sites from yet more plastic waste. It goes without saying that if everyone saved those plastic PET bottles for constructions like greenhouses, there would be less to clutter up landfill sites.
• It is cheap and easy to repair. You can simply replace the plastic bottle that has broken or been damaged by missiles or animals. All your bottles are hooked onto either wire or a cane or sticks. So all you need to do is unhook the line, slide out the bottles including the broken one(s), and replace it with a fresh one.
• It is sturdy and can withstand strong winds. Plastic bottles can't get blown away when they are pinned into place. The strength of your structure will depend entirely on how well the lines of bottles are anchored.

How to Build a Plastic Bottle Greenhouse

1. The bottles are washed to remove labels, then the bottoms are cut off. You will need to remove the bottle lids too.
2. Thread your bottles through whatever medium you choose to use to hold them in a line. This can be bamboo canes, or lengths of stick — though they need to be slim enough to feed through the bottle opening — or wire.
3. Once you have your basic frame, you then connect your canes or sticks with the interlocked plastic bottles already fitted, to the frame.

• All the greenhouses I have seen built with plastic PET bottles have used a wooden frame, which is surprisingly not terribly 'green' as trees have to be cut down to provide the frame. It also requires constructing, and that would mean calling in a joiner or woodworker in my case anyway. I am still thinking of alternatives to wood.

The plastic bottles have their bottoms cut off

the plastic bottles are placed over the bamboo cane

The canes are pegged into place on the wooden greenhouse structure

the roof is put on the plastic bottle greenhouse

An Alternative

Another way to build your greenhouse would be to interlock all the plastic bottles together, one on top of the other, as above, with the bottoms cut out to make a tighter fit, but without a central support. Instead, horizontal wires can be attached both inside and outside the greenhouse to hold the bottles in position, as shown in the photo below.

You will note that, in this project, the lids were left on the bottles, and I must admit I quite like that idea as it is one less place for insects to enter and make themselves at home.

Can you imagine how horrible going into your new plastic bottle greenhouse would be if you were confronted every time by nests of insects in the walls? Apart from the aesthetic appearance, a good deal of light would be cut out.

This photo shows the plastic bottle greenhouse built by 68-year old Linda Woollard as part of a university project.

As Insulation

Plastic bottles greenhouses can also be insulated to keep out cold draughts, and to cut down on self-watering when it rains.

Bubble wrap, which you can buy in rolls from any local DIY store, does the job really well.

insulating a plastic bottle greenhouse with bubble-wrap

As you can see from the above photos, making greenhouses from plastic bottles seems to be popular as a community effort. But I would like to build one for myself, primarily because of its cheap construction.

In Europe, building plastic bottle greenhouses has become a popular past time for many. I have been unable to locate information as to whether the plastic bottles stand up well under a hot sun, which is normal where I live (in southern Spain).

Plastic bottle houses stand up very well in sunny conditions in hot countries, but the plastic is not really exposed to a lot of sun, being filled first with sand and then covered by mortar. Filling with sand is NOT an option for a greenhouse as it then becomes a garden shed or something!

If any architect reads here, I would welcome your opinion, before I go to the effort of collecting thousands of empty plastic bottles.

How to Build a Greenhouse using Plastic Bottles

A plastic bottle greenhouse