Soil temperature is important because seeds need it to be above a certain temperature to germinate. I’ve been tracking the soil temperature in and out of the polytunnel
Once again the air temperature overreads in the day – what’s needed is an aspirated thermometer in a screen to get the air temperature right. However, the sun doesn’t shine in the night so the below freezing air temperature is true. The soil temperature varies less inside the polytunnel tha outside as well as being 5 degrees warmer at the coldest point, so it shows the advantage of having a polytunnel in keeping the seedbeds warmer.