Senior Project- Need Help- Chemical Engineer!
This is my first post. Thank you for reading. I am tasked with designing a 1 ft by 1 ft container that is to grow vegetables on top of our school parking garage for the cafeterias. Its depth can vary between 8 to 12 inches. The system should be as low maintenance as possible. That being said, I am looking to create a system that can be sustained by storing rain water only.
I am planning on using reflective tin on the sides and top of my system to reflect the suns energy away from the box, keeping the inside cool and hopefully causing less water to evaporate out of the soil (based on knowledge of thermal radiation).
PROBLEM: How do I keep as much water in the system as possible so that the one lettuce in the system always has enough water, but will not rot but also will have enough water.
SOLUTION: I am planning on using a mixture of soil and vermiculite (rather than perlite) to create a sponge like substrate that can store a lot of water. I am scared the use of vermiculite instead of perlite might cause root rot though.
1. I want to line the box (made of wood) with a plastic trash bag to prevent water from escaping. Will the trash bag rot if exposed to water for too long?
2. Is it necessary to have drain holes in any system? Is it possible to not have drain holes?
3. Should I use vermiculite or perlite?
BIG Q: If I used a soil mixture of soil and vermiculite, and used a plastic mulch and depended on rain as the only water source (roughly 2.2 gal per month) with NO drain holes at the bottom of the system, will there be root rot? Please let me know thoughts. I am on a deadline!
Thanks for your help! Its a very intricate project, but unfortunately I don't have the knowledge of gardening to complete it.