Frost is forecast and threatens to spoil the potatoes in the plot.
So the Chef covered his potatoes with fleece tonight. This will trap the warm air that is around the potatoes and act as a barrier against the frost. If the frosty air hit the potato leaves it will kill them
which would be a pity after all the tender loving care they have received to get them this far.
The Chef listens to the weather forecast every day so that he can take action to protect his crops if frost threatens the plot.