>>925358>>925350What I did for my little winter protection "house" is really just 4 stakes connected with cheap beams and everything closed off with a single layer of thin plastic foil - it's mainly a rain shelter (because the plant in question - Yucca elephantipes, doesn't like winter rain as the head shoots sort of funnel it and when it's too cool for that to evaporate it will start rotting eventually).
I hung up two 5 litre water jugs inside I spray painted black so it can absorb sun heat, plus water has a very high heat capacity, furthermore it releases energy while freezing.
I did place an additional heater inside today (cold wave here, might go to -10°C tonight) just so it doesn't drop below -5, have to manually turn it on/off though, got no outlet thermostat, just a timer I'll have to fiddle with a little