Harvest stems just as the first flowers reach maturity. Don't wait too long. Flowers at the top of the stem may be partially closed, but that's okay. The best time to harvest is mid-morning on a slightly breezy day. By midmorning, the dew has dried off the leaves, but it will be a while before any flowers wilt. Dampness slows drying and can lead to mold. When cutting, take as much stem as possible and make a clean, angled cut with a sharp pruner.
Choose a cool, dry, airy room such as a spare bedroom or large closet as your drying room. Low light is fine, but direct light will drain the color from your flowers. Hang flowers upside down in 1-1/2-inch-thick (at their stem) bunches spaced apart. Secure the bunches with a rubber band and hang from a 1/2-inch-diameter horizontal pole, a pipe from the ceiling, or a drying rack. Bent paper clips make perfect hangers for your bunches. Place newspaper or a dropcloth under the bunches to catch fallen leaves and petals.
To preserve fragile and moist blooms, use silica gel, available from florist and craft suppliers. In a shallow, airtight plastic or glass container, spread the flowers on a 1-inch-thick layer of silica. Carefully spoon more silica on top until you've covered the flowers with at least another inch of powder. Seal the container and leave it for 3 to 4 days. Or microwave the flowers, sealed in a plastic container, for about 3 minutes. Allow 15 minutes to cool.
Check the blossoms to be sure they are adequately dried. With either method, remove the blossoms carefully when they're finished drying, and shake or brush off the crystals lightly. Store dried flowers in arrangements out of direct sun to reduce the leaching of color from the blossoms.