Just a few pictures of my winterizing efforts for the tea seedlings and the new tea seeds. I use an Inkbird temperature controller to tun on the heat if the temperature drops below thirty-three degrees Fahrenheit.
For the tea seedlings on shelves in the hoop house, the controller is hooked to a 1.5kW space heater with a built-in fan that is placed on the floor towards the center of the house. Although there is no insulation, I do have plastic pieces draped down over the two end doors to limit air exchange with the outside.
The tea seeds in the temporary winter hoop house are placed on the floor (which is covered with a polypropylene felt underlay cloth). The same type of space heater is controlled by the same type of device which is set to heat at the same thirty-three degrees.
Because the seeds are on the floor, the ground provides some thermal mass and heat below them, while I've laid an insulating blanket over them. It is 3/16" thick foam, with foil on both sides and just drapes to the ground around the conetainers.