Everything turned out fine. Either it didn't get as cold as predicted last night, or my measures worked. I spent hours late yesterday watering all the garden and yard plants by hand (because I didn't want the hose to spray foliage which if still damp at freeze might harm the leaves?). I covered turnip and beet seedlings and the camellia with old sheets, heaped crushed sycamore leaves and put upended pots over the lovage, lemon balm, cranesbill, black-and-blue salvia and alstroemeria. Shifted my leaf mulch pile and gave thicker layers to most of the hostas, the ferns, lady's mantle, peonies and the chrysanthemums, which are just starting to emerge.
This morning went out to remove coverings and push the mulch back aside. The stuff from the leaf pile was warm. In fact not only did it protect the plants, but I think it gave some of them a boost. Both the old and divided piece of black-and-blue salvia doubled in height overnight! Pics of that soon. Right now I have some from a few days ago.
Lily of the valley is blooming: