The Problem Index → Garden
My greenhouse or cold frame cooks everything by noon
The answer is not a microcontroller. A wax cylinder opens the vent on the first warm Saturday in March whether or not you remembered, needs no power, and has nothing to update.
What actually works
◆ Proven
The wax-cylinder greenhouse vent opener
$35–60, zero watts, forever. An unvented frame hits 110–130°F by late morning on a sunny March day.
$35–60◇ Plausible
The greenhouse climate battery
If you're building new: blow the hot afternoon air underground and get it back at 4 a.m. 5–15°F of overnight lift.
$1,000–4,000, mostly at construction time◆ Proven
A sensor that WATCHES the opener
Don't automate the vent — automate the alarm. If it hits 95°F and keeps climbing, the opener seized or the vent is blocked.
Also searched as
greenhouse too hot · cold frame overheating · automatic greenhouse vent · greenhouse vent opener · forgot to open the greenhouse · hoop house heat