At rosybee we have an acre of ground that we sow with strips of borage and phacelia, in succession, to provide a great expanse of bee-fodder over the summer. We have been doing this for 5 years and although we still battle with other local invasive weeds we find that if we let the borage and phacelia self-sow, when possible, we get quite and effective crop of flowers without having to plough and re-sow.
Last autumn was so mild that the self-seeded plants get quite a lot taller than the carpet of seedlings we normally see through the winter. And then last week the frosts finally struck and we had a low of -7C one night.
The borage that really caught in and all semi mature plants are now black and ruined although I can still see seedlings that survived so I think it was the brittle stems that were the weakness. But to my surprise the phacelia, which is not meant to tolerate temperatures below -5C still looks lush and untouched even though it is 30cm tall in places.
Once the soil dries out enough to allow the tractor onto it we will resow the borage and by June the carnage of the frost will be forgotten and the whole area will be buzzing again. Both borage and phacelia are really easy to grow from seed - just chuck them at soil and off they go - and are in our top 30 ratings of plants for bees (see research for full results)