If salt is called for, as in moist potpourris, use plain salt with no additives. Salt with additives will destroy the natural chemicals in the rose petals. White and pale pink petals turn brown as they dry, and yellow petals may also turn an unattractive color. As a result, these sorts are best suited to wet potpourris, in which the petals are hidden from view. Use fragrant rose petals.
Roses are at peak fragrance and ideal for potpourri-making when the blooms are only half open.
In general, early morning is the best time to cut flowers for this purpose, since the blossoms perfumes are freshest at that time. There is not single best time of year, however, for peak fragrance. I have a personal recipe for a rose potpourri in the Recipes area of Just Roses. All rights reserved.