We just experienced the coldest temperatures this area has seen in over 40 years. Unfortunately some of our plants were unable to cope with such extreme cold, especially since it came before some plants had hardened off for winter.
There are some plants that are obviously dead, turning black and/or limp. Cordylines, Phormiums, some Hebes and other marginally hardy plants are probably dead. Other plants have brown or black leaves but may recover so it’s wise to wait a bit before removing all or part of them. My Daphne odora has pitiful looking leaves but the stems and buds look ok so it will probably drop those leaves and get new ones in spring. Star Jasmine, Evergreen Clematis, Escallonias, Drimys and several other broad-leaved evergreens might recover, if not on the top of the plant, possibly from the roots. Often this can take until June to see the regrowth. It depends on your patience and how much of a focal point that plant was whether you should replace the plant right away or wait. If you scratch the bark on the stems and see brown underneath, that branch has died. If you start at the top and keep checking down the stems you may find green under the lower parts of the stems, especially if that portion was covered with snow or mulch. If there is life left in the lower stems you can prune the shrub down to that level and it may recover.
Many spring blooming shrubs like Camellias and Rhododendrons set their flower buds in late summer and fall. Some of these buds may have been damaged by the cold and could drop without opening.
Hardy , established perennials should be fine. You can cut them down to the ground or to their basal rosette of leaves and they will probably send up new growth in spring. Some evergreen perennials look rough and tattered. For these, like Hellebores, Bergenia, Euphorbias, ferns etc. you can remove the worst looking foliage now by snipping off brown leaves. Acanthus (Bear’s Breech) looks like slimy seaweed now-just remove all off the bad leaves and it will send new ones up in spring.
Plants in pots above ground may or may not still be alive. Usually roots are less hardy than the top of a plant, so even if the top of a plant looks alive now, the plant may have dead roots and gradually it will die on top when warmer weather comes.
Mother Nature’s extreme weather is unfortunately beyond our control. I look forward to finding some new treasures to fill any voids in my garden.