winter greenhouse

What can I grow in my unheated greenhouse in the winter? Edible preferably! Any ideas greatly appreciated. :confused:

 

We did Winter Density lettuce last year and really appreciated eating it in March and April. I'll try sowing it earlier this year in the hope of a crop in February.

 

hi Dave. What sort of lettuce is that? Is it like Tom Thumb - hearted I mean. What about carrots?