I have a storm drain that goes to a cave. The air blowing up out of the retaining shaft is a constant ~55f. I was thinking I could just use this clear tarp to trap some of the air with a little venting by keeping one side open. On cold nights I can just bring the tarp down the ground and put a brick on top of it. Is there a chance this gets too hot? Or maybe doesn't actually do anything? Was hoping to put some of my tomatoes and early germinating flowers out here before the last frost.

by mrknowitnothingatall

10 Comments

  1. AgreeableCommission7

    Only way to tell is by monitoring the temp with a thermometer but seems promising. Night wouldn’t get too hot with 55 degrees, just once the sun hits that plastic is when you will get the temp spike.

  2. railgons

    Love it! I’d build a little wooden frame around it. Insulate the parts that don’t get direct sun and put the poly on the rest. You could build a window frame with a wax opener, which would vent it automatically.

    One other thing to consider: Make sure the air/gases aren’t anything that could be toxic to the plants, or concentrated and become dangerous.

  3. AgreeableCommission7

    Each plant is different but as long as the soil is moist and they arent getting direct sun they can handle some heat. I have a small greenhouse and my ventilation failed and the temp got up to 98 and the seedlings were fine. I would be more concerned about temps dipping too low. If temps are too low it can stunt growth or prevent sprouting.

    I try and keep my day temps in the 70/80s night temps in the 60s and try not to dip below 55 but it happens occasionally.

  4. Outdoor_lad22

    Oh I’m laughing 🤣 but this is actually good. I love how gardeners just make things work

  5. Lyrical_Echo

    Well worth a try! As long as the gases aren’t toxic, as someone else mentioned. I hope it works for you.

  6. t0mt0mt0m

    Play with it and get some data logging going to confirm your theory.

  7. mrknowitnothingatall

    First trial run overnight. Temp got down to 42 outside but 56 inside. Because of the damp air it is at 99% humidity inside. Is that going to be an issue?

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