Q. (See above question 1881) If you can't use the unused hadassim, can you just throw them away in the regular garbage, since they were never used for a mitzva?
A. Shulchan Aruch (O.H. 664: 8 and 21:1 and Shaarei Tzion ibid. 20) warn on not stepping on leftover mitzvos as leafs of Hoshanos or threads of tzitzis. Therefore Horav Shlomo Miller's Shlit'a opinion is that leftover schach and arbaas haminim should not be thrown into the common garbage bin, since they were used for a mitzva. Rather they should be disposed in paper bags with the rest of leaves and branches that will end up being buried in land fills. They may also be double wrapped or bagged and then disposed off in the regular garbage. This is unnecessary in unused arbaas haminim, that although were prepared for mitzvos, were actually never so used.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a