1. Cut oranges and lemons into 1/8-inch-thick slices. Places slices in a 150° F oven on an open rack to dry the slices. Leaves the slices in the oven for 3 hours, turning them over after 90 minutes. (Edges should not be brown.)
2. When fruit is dry but slightly moist, remove from oven and place on wire rack; air dry for 3 hours. If wreath form has flat edges, use a serrated knife to gently round.
3. Use straight pins to attach the fruit slices to the wreath, overlapping the pieces to cover the entire foam wreath.
4. Wire sprigs of greenery together, then secure the bundle to the wreath top. Wire a few holiday balls and ribbon to the greenery.