I have an old greenhouse which you could describe it as 'well-ventilated': it lacks a door and several glass panes, and the rabbits had set up shop beneath it, the better to bask in the warmth and snack on the weeds.
But when a gardening friend pointed out that any growing space was precious, I decided to try growing something - anything - in it.
Mr. P kindly removed the dusty old staging. I then weeded the soil, and as a short-term measure to banish both bunnies and weed, laid down some weed-suppressant membrane.
Then I bought some large growbags from Unwins (Unwins Growbags) and filled them with compost.
Now I'm growing salad leaves, and herbs like lovage and chervil, and hope to continue doing so into the autumn. I'm sourcing replacement glass planes from the local glazier to source replacement glass panes so that I can keep the greenhouse snug when the temperature really drops.
The rescue effort was successful, and growing salad under glass has been a revelation.
Initially I started with hot, peppery rocket, which was far spicier and sharper than any bought in store. We ate this in great quantities, scattered with capers and coated in dressing.
Then I became more adventerous. I sowed Red Mizuna, Mespoona, Lovage, Silene, and Sculpit (Silene inflata), as well as Chervil and Lovage.
The Silene and Sculpit are an acquired taste. I like them, but other family members think they taste a bit too much of minerals and earth (or, less charitably, too much like a weed). The Mizuna and Mespoona are probably more to most people's taste. They taste more salad-like, and are reminiscent of mustard cress. The Mizuna, in particular, has a pleasantly crisp taste.
Enjoy your salad days!