First off, thanks to everyone on this forum for sharing their projects, knowledge and ideas. I used it extensively when designing my system. I want to share my build process and results with everyone… Constructive feedback is appreciated.
I live in Toronto, Canada so our growing season is limited. We also have a racoon problem in the city so growing any veggies outside means you’re unwillingly making a food donation. So I decided to build a greenhouse to extend the growing season and solve the animal issue.
Here are the specs at a high level.
- 4’x10’ growing area
- Double pane insulated glass on two of four walls
- Insulated roof and insulated non-glass walls
- 4’ deep pit for roots, 7’ tall growing area
- Automation through raspberry pi and smart plugs
- Insulated root box sunk 4’ into the earth to temper extreme weather conditions
- Copper tubing buried under the pit for future use (exact use TBD, briefly used it to cool the nutrient water during summer)
- Rubber pool liner seals the root box area from (most) insects
- Six netafim coolnet pro nozzles with check valves mist roots. One diaphragm pump feeds 80 psi nutrient water to nozzles through 1/4” push-lok tubing.
- Small pump with float switch drains excess water from pit to outside (non-recirculating setup)
- 22 growing spaces, each spaced about 12” apart
- 6 growing zones - each zone is made up of white lexan plastic trays and cedar framing. Plants sit in 2” net pots with foam inserts.
- LED lighting provides additional light on overcast days, and at dusk & dawn, scheduled through a smart plug.
- Small electric heater keeps the space 10 degC when OAT is -25 degC
- Small fan to exhaust air on hot days
- Nutrient solution stored in 100L bin. I manually add water and nutrients.
- rpi schedules the pump to run every 2 minutes for 2 seconds during the day, and every 5 minutes for 1 second at night.
- Need to insulate lexan sheets (the ones that make up the tray of each grow zone). Light and heat is transferred through the plastic to the root box. Causes root temps to get above 15 degC. This is a work in progress, I’m gluing 1” thick blue foam sheets to the bottom of each zone.
- Cheap Aliexpress nozzles clogged and provided inconsistent spray from day 1. They also allowed water to drain through them when pumps were off. I’ve replaced these with the netafim nozzles, they work much better.
- I initially recirculated runoff water back into my supply. Even with filters I found this led to algae growth. I never had issues with the algae but figured it could lead to issues so I changed to a non-recirculating system.
- The growing area and root area both get too warm during summer. I’m planning to supplement the exhaust fan with a fresh air fan. I’m also hoping the insulated lexan will help with the root box temp.
I initially used about 70 L/day with the cheap AliExpress nozzles. I’m down to 20L/day with Netafim nozzles and hoping to reduce this further. I plan to measure the volume of waste water on a hot day and cool day. This should be a good starting point.
Thanks for reading!