One thing we do here at KFF is as the nights get colder is add some insulation on the north side of our houses. Our houses are oriented East/West, not by design but more because of the lay of the land. As the sun comes from the south, we try to keep that side open as much as possible to the sun but insulate the north side where no solar gain is going on.
Here’s Dylan and I laying ou the insulation- it’s pretty light so we can lay it right on top of the spinach and it’s okay. We use bubble foil (best price here http://bit.ly/UEBoI3). It comes in big 125 ft rolls, shipping will kill you so we have planned getting it when we are near Farmer Boy’s stores.
As it is only staying up for 3 months max (December- February) we only attach it to the top with a simple loop of duct tape. Make sure to get it nice an tight to the soil on the bottom as you are going to want to attach it down there as well….
We attach the bottom with ground cloth staples right into the soil. Here’s what it looks like after it is installed.
Note the air space between the insulation and the top of the rollup to allow for ventilation. having the insualtion there also allows us to store the covers during the day right up against the edge. They are in the center of the house now but harvest is easier if they are against the edge and you aren’t walking or kneeling on them.
Here’s a picture of the finished haygrove. We only put the insulation up two feet in here as it was more to block the cold air from seeping in from below the edge of the plastic. The haygrove doesn’t have a baseboard as it’s meant to be a 3 season house and thus cold air gets in relatively easily. If you look closely at the greens in the first bed you can see the edge effect causing the outside rows of greens to grow more slowly.
Another thing we do as we build permanent houses is add 1 inch blue-board around the perimeter from soil level to a foot down. This breaks the cold and frost creeping in and seems to really help the edges to stay warmer.