For best results, pick flowers and leafy plants around noon. Orange and yellow blossoms retain their colors best; most blues and pinks fade; reds turn brown. Lay each plant between two layers of absorbent paper (best for fleshy flowers) or waxed paper (fine for thin or delicate types). With thick heads, such as roses, press the petals individually. Weight the flowers with a heavy book or bricks; leave them in a warm, dry place for at least 4 weeks.
To make a framed picture, cut a piece of heavy construction paper to fit the frame. Gently arrange the flowers on the paper to form a spray, bouquet, or other pleasing arrangement. With a toothpick, dab a bit of white glue on the back of each plant; press it in place. When the picture is dry, lay it facedown in the frame. Place cardboard backing over it, and push 1/2 inch brads into the frame to hold the backing. Cut wrapping paper to fit, and glue it to the back of the frame as a seal.