Question
We are in NE Mississippi. These 5ish year old plants may havepossible frost damage.

of the 8 or so plants..some higher than my 5ft head, two of the plants have this...?

I have picked off some leaves. Seemed too much to do all, and now I'm not convinced that has helped.

Please help me save these beautiful, cheap, easy (so far) plants.

Answer
Roberta,
The blackened leaves are a sure sign of low temperature injury or frost damage. Fertilize them to help strengthen them and spray in the late fall with an anti-dessicant then erect burlap enclosures to further protect them from the damaging winter winds.
Good luck.
Ed Gulliksen