1. Prepare pots. Place gravel in the bottom of each pot for weight. Cut two pieces of plastic foam to fit each pot, trimming the top piece to fit the rim exactly. Secure the two pieces together with floral picks, then glue the plastic foam into the pot so the top of the foam is even with the rim.
2. Add tall branches. Insert the birch twigs in the back of each pot for height. Next, place the tallest branches of evergreens in front of the twigs. Insert additional evergreens at the sides and front, staggering their heights so they are progressively shorter as you work toward the front of the pot.
3. Add red accents. Insert the winterberry branches and rose hips evenly through each arrangement, positioning the branches so they repeat the lines of the evergreens.
4. Insert pinecones. Attach pinecones to lengths of #19 floral wire and use the wire ends as picks to secure the pinecones to the plastic foam base.
5. Place pots in window boxes. Add greenery at each end so the branches seem to overflow the box.
For a horizontal window: Make the arrangements alike; when you place the pots in the window box, they will blend to make a single long display.
For a tall, double-hung window: Place a few long branches asymmetrically. This provides a more vertical emphasis.
For a planter display: Follow the same procedure as for the window box arrangements, but position the birch twigs in the center of the pot rather than at the back. This keeps the design from looking flat. Place the tallest evergreens around the birch twigs and work toward the edges of the planter with progressively shorter branches. Fill in the middle of the design with greenery and add the berried branches and pinecones last.