I was gifted 2 raised planters - 2'x4' and 2'x6'. They have a framed wire "top" that covers the whole structure, 2' tall from the top edge of the planter. The planting beds are 18" deep, with the bottom of the bed less than a foot above the ground (the planters are shorter than normal raised planters since the previous short-stature owner cut the legs several inches; but works great for me since I'm also short).

I was thinking I could cover that frame with row cover and grow winter vegs but then I thought of "bridge freezes before road" - the warning signs when crossing bridges in winter. The thinking being that the planter will freeze easier because it's elevated like a bridge, there will be cold air flow under the planting bed. Right? Or do you think I can use the planters as winter planting beds and with the freebie built-in structure for cloth cover?

I don't have a dedicated veg garden, everything is interspersed around and in-between the perenniel flower beds, so I don't really have a place for traditional hoop/row covers, hence I've never done much winter gardening. But now that I have these raised planters, it got me thinking...