The materials I used to create our hothouse which is approximately 1600mm wide x 1900mm long x 1800mm wall height and 2100mm overall height are as follows-
1000 x 1.25L soft drink bottles – Any are fine but I found long straight ones like Pepsi are best.
80 x 1.8m x 20mm lengths of electrical conduit – I had access to lots of old dirty pieces so was lucky. You could use old off cuts joined together (which i did for some) or any other material you have on hand like cane stakes or long straight sticks.
30 (approx) x 1.8m x 90mm x 35mm length of treated pine – I used treated pine but you can use whatever timber is available in your area.
Screws or Nails to construct frame and attach conduit – I used batten screws for the frame and roof crews for the conduit.
Tools you’ll need are –
- Angle grinder or sharp knife
- Tape measure
- Basic hand tools
Step 1: Preparing the Bottles
The major thing you will need to try to to with the bottles is cut the bottoms off ! I used an angle grinder but you’ll easily use a pointy knife or scissors if you are not comfortable employing a grinder. I kept all the bottoms to reuse as paint containers when working with student but they might enter the bin . I found the simplest thing was to not cut rock bottom off the bottle which will be rock bottom on the row when fed onto the conduit. Instead I drilled an entire within the bottom with a 22mm bit so it had been a firm fit on the conduit. very similar to the opening of the bottle.
Remove the lid and label. I found the simplest thing was to use a knife and cut the label then peel it off. i would not waste any time on bottles that have the label completely glued on, it’s to time consuming removing all the paper and glue.
Wash the bottles out !. it is best to scrub them with soapy water and rinse with clean water to get rid of unspecified sugar deposits or foreign materials.
Step 2: Frame
Make the frame to suit your own needs and design. The limit is really your imagination. I went with a basic shape made up of 6 individual panes and a door. I assembled the whole thing then broke it back down again to fit the bottles to the individual panels.
Step 3: Attaching the Bottles
Next step is to feed all the bottles onto the conduit.
Firstly cut the conduit to length to suit the panel you are constructing. Drill a hole in both ends of the conduit and place a screw in the bottom hole. I started with the full bottle with the 22mm hole in the bottom and then fed as many bottles as needed onto the conduit. A lot of the time you will need to alter the last bottle placed on to get the correct gap for the top screw. Do this by cutting more off the bottom of the bottle of to suit.
Once the correct number of bottles and the correct gap is attained, lay the conduit (with bottles) onto the frame and attach the two screws to the frame.
You can see in the photo’s the correct orientation of the bottles to allow water to run away.
Step 4: Construction of the Panels
Once all the panels are done you can move them to the site of your hothouse and reassemble the frame. It’s probably best if you have someone that can help you with this step as it’s a bit tricky by yourself !
Step 5: Growing
As my hothouse was replacing an old green house I cut down and altered the steel stand so I could reuse it in the new hothouse. I also fitted a spray self watering system to the roof so everything is watered once a day in spring/summer.
Step 6: Final Word
This project was a great way of incorporating recycling into a school garden program. We were able to reuse soft drink bottles, old electrical conduit that was unable to be used and an old greenhouse stand. The students were amazed that things which were useless by themselves could be re purposed into something very functional, which we now grow all our seedling in.
While not as efficient as a glass or a fully enclosed hothouse the bottle hothouse is on average 4 degrees hotter than the outside temperature. All our seedlings have survived and thrived when they have been planted out. I believe the plants are hardier than plants grown in enclosed hothouses as they have some exposure to the outside conditions without being effected by wind, frost of glaring sunlight.
I’m trying to grow banana’s in it now !