The Worst of All Frosts

In the UK, a bitter east wind (forecast for later in the week) provides the worst of all frosts - a penetrating one. It might take more than horticultural fleece to protect sensitive plants.

Fleece insulates plants by preventing radiant heat loss and to some extent restricting air movement around them. But I don't think it will be strong enough to protect against strong air movements; these will brush aside the still air (because it's porous) and allow freezing temperatures to reach the plant surface.

Much protection can therefore be obtained by blocking up cracks in doors and windows through which this wind can pass. I am also going to cover plants with newspaper overnight to help reduce air movement around them. Fortunately, daytime temperatures should remain above freezing.