Growing Cabbage, broccoli, & Onion in Polytunnel greenhouse

Today while the weather permitted, my partner and I got a truck load of compost to go on one of the gardens. The truckload of compost cost $37 after tax. Before spreading the compost, we made a polytunnel using water pipe attached together and held in place with small pieces of rebar in the ground. Afterwards, we assembled cardboard in the shape of the polytunnel and then spread 6 inches of compost on top of the cardboard. We collected rocks and lined rocks around the bed to contain the compost.
Then we transplanted cabbage, broccoli, and onions throughout the compost bed and watering with rain that was collected on site. Because we are transplanting in late February when the nights are still between 20-40 degrees, we went ahead and covered the poltunnel with plastic and secured the plastic with long pieces of rebar and rocks. I will have to make sure to uncover the polytunnel on hot or warm days or use garden cloth to cover the tunnel. The idea behind constructing tunnels over the garden beds is to use plastic when it's cold and then use garden cloth when it's hot and to keep bugs out.
Below are some photos I took of the bed to show you the first garden we have put out this year. Although I have had some plants growing throughout the winter, it feels like I'm actually gardening now that I'm transplanting.