I have been moving my plants outside during the day and inside at night. I'm going to be away for a few days, and I need the plants to get sunlight (although it has been cloudy and raining lately). I thought of creating a DIY green house with plastic bags (Type 4). In here, it's said that type 4 is suitable for plants and gardening. And in here they talk about plastics to use for greenhouse, but I think they are going too specific in the subject and at large-scale.
When I put them outside, they get daylight, but no direct sunlight. With a light measurer I can see there is quite a difference by having them inside right next to the window, and outside right next to the window (way more light received outside).
This is the plastic bag greenhouse I made. Everything is sealed. I was planning on putting some sticks so it would be a bit higher as well, and rain would just fall, like a "roof". The plants are small tomato and red peper plants, which germinated and sprouted 3 leaves, so I replanted them there because I can't move them anywhere else right now.
In here it says that it works well for humidity retention, and frost prevention. On this site, they asked here the best type of plastic, but neither the question nor answer mention a PLASTICBAG greenhouse. On this site as well, they used plastic cups and I have also used them when germinating. They worked well, but it was not as cold as it is now during the day. Same here for types of plastic sheets. They mention a thickness of 3.5 or 4mm at least.
Can regular plastic bags (like for freezing food) be used as a plastic greenhouse to not only protect from frost, but also to retain HEAT? (as it is getting colder during the day, and plants need more warmth as well as humidity). These plastic bags don't even have 1mm in thickness I guess.
EDIT, more info:
Average temperature these days: 8ºC daytime, 4ºC Nighttime. Quite windy (from 2 to 10km/h) average.
Plants: Red Pepper plants, from supermarket, extracted some seeds. Tomato plants, bought from plants store. Marmande VR Tomato Holand Type. Harvest from 5 months.
Very early fruitful variety. Valued and grown for its early harvest. Low bush. Pale red, good sized, broand and rugged fruits.