I can't tell exactly what's going on in the first two pics, but the peony (under the black plastic trash bag) looks like it could be burnt toast by mid day.

Brandon, do you think sun on the black plastic is the enemy here? I agree its dangerous but on a heavily overcast day (Its still raining a bit) do I still stand the same chance of baking them?

The top one is a plastic table cloth attached to the top of a fence over a foot tall beech. I figure it's like a mini greenhouse that protects the fella from frost but allows the breeze in from the side.

The second pic is 2 darned plastic shopping bags over the top two feet of this 4 ft tall young crabapple. I peeked in there and the leaves look fine, so far. Figure the white is better than black, its what she had though.

From what I was told you aren't supposed to have the covering actually touch the leaves you're trying to protect. I could be wrong though.

JQ, you are correct.

Tornado, I don't know. It doesn't look like such a dreary day in your pictures, but maybe they are deceiving. Personally, I don't think I'd take the chance when it would be just as easy to remove the plastic and throw a sheet over the top.

I don't do anything to protect trees from frost, with one exception, that being very small plants that have not yet had a good strong growing season to get established. I am protecting one tree at the moment, a friend's 18" tall Eucommia ulmoides that was just about to break bud when the last few cold blasts (one down to 14 F and the other to 17 F) came through. It was planted last spring and only put on about four inches of growth. The species is hardy here but its foliage has shown some sensitivity to late spring and early fall freezes. With this new little one, I didn't want to chance it not having the energy reserves to grow a replacement set of leaves. What I am using is two 3 gal. plastic containers, the bottom cut out of one, and both lined with bubble wrap. Nested upside-down, they form a sort of teepee over the plant. So far this arrangement seems to have worked pretty well. There is a slight blackening on the edges of the tree's bud scales, but the buds overall remain plump and green.

BTW Toronado, how did the Gum Bumelia tree do for you last season--the one Missouri Wildflowers sent you by mistake in place of the Nyssa you wanted?

yup, the half dozen leaves on the crabapple which were touching the white plastic and were wrapped into it well got damp and shriveled a bit, the rest of the tree was fine. The peonies couldn't have cared less about the black plastic, go figure.

Tonight I'm just covering the peonies.

Cacau, I'm amazed you remembered! The Gum Bumelia is still dormant. I planted it at work where it received minimal care over the winter but also nothing bad has happened to it. No signs of life yet.

It's in the low 20s here and I haven't covered a thing--You're going to a great deal of unneccessary trouble. About the only thing you'd ever need to protect from a late frost would be lilies that were up. They won't recover the same year. (That's true lilies, not daylilies.) Blooming fruit trees and strawberries might be in trouble too. I use row covers on the strawberries--much better than plastic--even cloth is much better than platic.

The two Gum Bumelias I have did pretty well last year and are starting to bud out now, but they're in containers on an enclosed cold patio. I repotted them about six weeks ago into a friendlier mix and noticed the roots are kind of fleshy but still had done a great job of penetrating the too-dense clay I had them in. It's not surprising that this plant can thrive in the southern Great Plains. The thorns aren't bad, and are actually rather dull compared to Maclura or species Gleditsia.