Spread the orange peels, lemongrass and spearmint on racks or screens set over baking sheets. Set in a dry, dark place until dried but not brittle, 5 to 10 days, depending on the humidity.
Using scissors, cut the orange peels and lemongrass into 1-inch pieces and place in a large bowl. Lightly crush the spearmint leaves and add to the bowl along with the rose hips; toss gently. Pack the tea in small tins.
The tea can be kept in airtight tins for up to 3 months.