Q. Is it permitted to use as schach for the suka, flowers that have a good smell?
A. Rema (O.H. 68: 2) quotes two opinion whether if one is allowed to use good smelling hadassim as schach for the suka. Ran (Suka 18a) maintains that it is muktza also for its smell and should not be used. Mishna Berura (25), quotes Taz and Pri Megadim that permit.
Chashukei Chemed (Suka 12a) is also lenient since the main intention in using the flowers is as shach, the good smell is an added benefit.
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as advised by Horav Shlomo and Horav Aharon Miller Shlit’a