One circle of greens is a wreath (rhymes with “teeth”). The plural is “wreaths” (rhymes with “heaths”). In both cases the TH is unvoiced (like the TH in “both”).
To decorate something with wreaths is wreathe it (rhymes with “breathe” with a voiced TH like the one at the end of “bathe”). He or she wreathes it (also with a voiced TH).
On the podcast this week, we air our traditional Christmas episode.
Final week of the book sale! Through the end of the year, buy the Common Errors in English Usage book now for $15 with free shipping in the US.