Wait until they show fresh growth
Many trees, bushes, and plants around the Valley are looking pretty sickly these days, due to heavy damage from the recent cold wave, where morning low temperatures dipped below freezing Valleywide, and into the mid 20s or below in outlying suburban areas.
But this isn't the time to cut back what appears to be dead vegetation. Brian Whitfill, owner of Whitfill Nurseries, says you should leave the plants alone for now. He suggests waiting until at least March 1, after the danger of any killing frosts is past and plants have started to show new growth.
Whitfill says until then, it will be difficult to tell which parts of the plant are dead and which parts are still healthy enough to bounce back. Once you see where the new growth is emerging, you can safely assume the areas not showing growth can be pruned.
Whitfill adds that in outlying areas of the Valley and in rural areas, you might want to wait until mid-March, since the average date for the last likelihood of frost is around March 1st.