Dried rose petals are a special ingredient in advieh, a delightful spice mix used in Persian cooking...surprisingly often in meat & savory dishes. An easier way for some may be to buy rose water & substitute a tiny bit, if drying rose petals is too difficult. My kids loved getting to collect & dry the rose petals with me.
Rose petals are edible, but you want to make sure your bush has not been sprayed with chemicals. I prefer to pick the wild roses that grow in my area, as they have that strong, classical rose scent. Garden varieties that also have the classical rose scent are good options, too, especially if you grow them in your own garden organically.
Ideal picking time is after the dew has dried, but before strong sun is causing them to fade. This late morning time is usually when they are most fragrant.
Pluck the petals. Many advise not washing them because the water can cause them to brown in traditional drying methods that take longer, because the water causes them to begin to rot. If the petals are a bright color (they don't show bruises like white petals), I wash them in a colander anyways, to make sure to get rid of all the tiny bugs.
Pat the petals dry with paper towels. Place in a single layer on a large baking sheet. Place in the middle rack of your oven. Turn your oven on to "preheat" and after one to two minutes turn off. Set a timer so you don't over heat them! You want the actual temperature to be about just under 100 degrees F. Leave for a while, then check on them. If the oven has cooled, and the petals are not completely crispy feeling, repeat procedure. I usually do this about 3-4 times. After the last time, I remove the petals before the oven has cooled. You want to put them in an air tight container while they are still crispy from being heated, because if you live in a humid place, letting them sit when they have cooled will cause them to absorb some moisture again, which may allow them to mold while stored. Store them away from sunlight, so they don't fade.
Use in cooking, potpourri, or grind to a powder & use in this Persian spice mix: mypersiankitchen.com/advieh-â€“-a-blend-of-spices-for-persian-cooking/
(If the link doesn't work, you can type advieh into the search bar on the mypersiankitchen.com blog. Or, it simply is a mix of 1 tsp each of ground: cinnamon, nutmeg, dry rose petals, and cardamom, with 1/2 tsp. of ground cumin.)