When we lived in Oxford, we put a polytunnel in the back garden in the autumn. One of the lessons we quickly learned as the following spring warmed up was just how hot they can get and we had to quickly install some ways to ventilate it without just leaving it wide open. That is why, when we got a polytunnel for our present home, we opted for one with some built in ventilation – net panels on the top part of the front and back doors and a section on the side that can be rolled up, leaving a further net panel.

Now our spring-installed tunnel is coming towards the end of its first autumn, the problem is reversed and we needed a solution to keep it a bit cosier. Over the past couple of weeks, I’ve been building square frames that I intended to cover with polythene and fit inside the door frames. It turns out that I’ve got a bit rusty at woodworking. Both took a lot longer than I expected and, despite my attempts to measure carefully, only one fitted. In the end, the other one has been fixed to the outside of the far door frame using some L brackets.

Almost immediately, it feels a lot warmer in there. In fact, I’ll need to consider leaving the front panel off for a few more weeks or check frequently to ensure things aren’t going mouldy in the warm humidity. Next time I build a polytunnel, I’ll try to remember to get the winter glazing frames built before the doors go on, which would probably have been a lot simpler than trying to fit and measure in an occluded place. For now, though, job done.