Hoop House Film
I garden on Whidbey Island, Washington. Due to the very moderate climate (daytime highs in the 70s and nightly lows in the low 50s as well as frequent cloud cover through early July), I built a hoop house using translucent 6-mil low-density polyethylene with UF-resistant additives. The hoop house has raised beds which I cover with either translucent PE or black PE to increase soil temperature. My questions are: 1. Would I be better off to use transparent film for the hoop house? 2. Given that the light hitting the beds has passed through PE, what would be the best color or construction for the ground cover film?
Island County Washington
You may have overheating issues using a transparent film for the hoop house on sunny days unless you have a good ventilation system in place. What is your intended use and timing of use for the hoop house (season extension, winter growing, etc.)?
Are you going to be planting into the plastic and leaving it in place all growing season or just using it to warm the soil prior to removal and planting? Clear plastic allows for higher soil temperatures (this is the type of plastic used for soil solarization) but the light coming through does allow for weed seed germination. Black plastic will still warm the soil, but does not have the weed seed germination issues and you can cut small holes to plant into. If you are growing tomatoes, some research has found that red plastic is useful for increasing tomato yields.
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Thank you for the reply, Here are responses to your question. I use the hoop house to provide a warmer environment and allow plants that require warmer temperatures than is usual for the Pacific NW. This works somewhat but due (I think) to low night time temperatures, ripening is often late. This is particular bad since light strength diminishes in late August because to the northern latitude. My idea is to use circulated solar heated water to keep the night time soil temperatures above 65F. I will transplant tomatoes, peppers and egg plants into the solar heated (at night and on cloudy days) hoop house.
Regarding the use of polyethylene, I leave it in place around the transplanted plants.