Leaving flowers in desiccant too long makes them very fragile, so remove flowers right away once you've determined that they're dry enough. A Note About Sunflowers . Keep approximately 24 inches of stem attached when you dry sunflowers. Cover the heads with crystals, but let the stems hang over the container's side. Seal it all in plastic kitchen wrap, and leave untouched for at least a week to 10 days.
Large sunflowers take a long time to dry, even in silica.
The latest and fastest method to dry flowers is to use a combination of silica gel and a microwave oven. Some dried-flower enthusiasts claim that you can use layers of paper towels rather than desiccant, but results may vary. For more reliable drying, prepare your flowers using the standard silica procedure described above, and then microwave them. To get truer color, dry the flowers one at a time to avoid overdrying them. You may need to switch to a smaller container if your usual one doesn't fit in the m oven, but make sure it is microwave-safe.