Q. Can women say the brocho on the flowering trees outside, since they don’t say kiddush levana (the blessing on the new moon) outside because of tzniut? Is it also not a mitzva shehazman gramma?

A. Poskim maintain that women should bless birchas hailonos. Chazon Ovadia (2: p.8) and others explain that it is not considered a mitzva that depends on a fixed time (zeman gromo), since it is not determined by a specific calendar date, but rather by a botanical phenomena that may occur at different dates, depending on the weather, latitude, etc. Thus it is similar to a shecheyanu blessing on a new fruit, that women do recite. (See Har Tzvi 1: 118). There are also different opinions in regards to birchas hachama for women.
A number of different reasons are mentioned on why women are exempt from kiddush levana. One of them is indeed that since it is usually recited with a large group of men present in the streets, tznius or maintaining that the honor of a woman is to remain in her home, is an issue. (Chabolim Baneimim 3:8, – See also Shalmas Chaim 1: 98, in regards to women lighting a menorah in the street).
Horav Shlomo Miller’s Shlit’a opinion is that since birchas hailonos can be recited rapidly, it is only once a year, it does not require a group, and can even be said by watching the flowering fruit tree from a window, women should say it.

Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a