Would like to hear your experiences if you do.

Thanks.

We have a poly-tunnel if that counts ?

Sure does,would love to hear about it.

I don't have one, but the experience of my uncle, now deceased is fun to talk about. He lived in Boseman, Montana for it's proximity to Yellowstone Park. The growing season there is short and my uncle had trouble growing tomatoes. The plants wouldn't grow a decent sized fruit before the frost (this is late 40's and 50's). He had a trench dug and lined the trench with plywood, filling the gap between the dirt wall and plywood with rotted horse manure, then covered all with plastic sheeting. The manure gave off enough heat to keep the tomato plants alive till he could harvest the fruits.

Rotted manure? First I have ever heard of that.

MoBOB,
As I understand it, horse manure has too much (nitrogen maybe?) of one nutrient or another and will "burn" plants if it's put on the beds. If the manure is allowwed to weather in a pile, some of the excess nutrient dissipates and the manure can then be safely used. I believe this is because horses have a 3 chambered stomach vs. the 4 chambered stomach of a cow or other true ruminant.

JPickett - Thanks for the info. It makes sense.

when I built our raised bed, I added a top post system. In the summer we use a bug mesh over the top to provide a little sun shade and in the winter we staple a thin (maybe 2 mil) clear tarp over the top and sides. Don't need to have it down all winter, just the few freezing nights per year we get.

Works fine. in fact just pulled out 2 dozen carrots and a dozen peppers this week.