Only petals of some flowers such as rose, calendula, tulip, chrysanthemum, yucca and lavender are edible. When using just the petals, separate them from the rest of the flower just prior to use to prevent wilting. Roses, dianthus, English daises, marigolds and chrysanthemums have a bitter white portion at the base of the petal where it was attached to the flower. Break or cut off the bitter part of the petal before using. Freezing does not work well in preserving flowers.
Daylilies are an exception.
However flowers or petals can be successfully frozen in ice cubes to enliven a drink any time of year. Some flowers can be dried, but the flavor is altered. Nasturtiums, lavender, carnations, chive blossoms, rosemary, sage and hyssop are very flavorful. Violets and petunias are sweet. Hollyhocks, pansies, calendula and squash flowers are mildly flavorful.