A well-made, quality wreath should last the entire season and hold on to its color and needles easily. Keep in mind where your wreath will be hung. A wreath that is hung between a front door and a glass storm door may dry out faster when facing south or west.
A greenhouse type effect might make the wreath needles dry and brittle. In this case it's best to hang the wreath on the outside of the storm door. A wreath that is hung outside should need no special attention and last several months. So don't be afraid to redecorate for Valentine's Day!
In New York we are lucky enough to live in a climate with plenty of moisture. So any wreath that hangs outside will have plenty of humidity to stay green and fresh for several months, lasting well after the Christmas season, and brightening your home on the dark days of winter.
There is no need to spray a wreath with any type of shellac when hung inside. Simply pick your favorite spot and hang it. If the wreath is directly above a heat source such as a vent or fireplace, you may want to lightly mist the wreath at the same time you water your real Christmas tree. Quality wreaths have been known to retain the needles when left undisturbed for several years. While they will turn rust brown, you might want to redecorate with complementary gold's.
Novelty items such as kissing balls, centerpieces, arrangements and mantle pieces that are made with oasis should be kept damp. This will help prolong the life of these cut items, that should last 3 to 4 months.