Posted: 01/02/2016 at 14:19
If the greenhouses are unheated then you can't sow anything tender yet, like half hardy annuals. You can sow sweet peas, broad beans, onions, some peas. Not tomatoes yet. I sow mostly in March in the unheated greenhouse, or indoors or in heated propagators.
If you prune group 1 clematis now, such as montanas, you will lose a lot of the flowers.