Roses are best picked between 10:00 AM and Noon. You want to pick them after the dew is off but before the sun has zapped all the essential oils from the flowers.
Put as many fresh petals in your clear jar or crock as will fit and cover with distilled water. (They must be completely covered or the exposed petals may mildew). Cover and let the sun shine on your container. Like making sun tea, as the water heats, the color of the essential oils are extracted into the water giving you your floral water. Depending upon the weather you can have your floral water after only one day in the sun.
Note: Vodka is an optional addition to the water. Since the concoction can turn, leaving a little floating island of mildew atop the water, we usually add a little vodka which kills bacteria and prolongs the scent of the rose water. (Suggested vodka is 1/2 cup to a gallon of distilled water).