Question: When’s the best time to say the beracha on the blossom? Should women also say it?
Answer: The Gemara (Berachos 43b) writes that one should recite a beracha on a tree when it blossoms in the month of Nissan. The Shulchan Aruch (OC 226:1) writes that this beracha can only be recited once a year.
According to some poskim (Halachos Ketanos 2:28; Kaf Hachaim OC 226:1) the beracha should only be recited in the month of Nissan, though most poskim (Ritva, Rosh Hashana 11a; Mishna Berura 226:1; Aruch Hashulchan OC 226:1; Tzitz Eliezer 12:20:3) write that one should say it whenever when one first sees the blossom. R’ Ephraim Greenblatt (Rivevos Ephraim 5:173) writes that he witnessed R’ Moshe Feinstein say the beracha in Iyar.
Thus, R’ Ovadia Yosef (Yechave Daas 1:1; Yabia Omer OC 8:8:4) writes that one should ideally wait until Nissan to recite the beracha, though one can still do so afterwards. R’ Yitzchok Yaakov Weiss (Minchas Yitzchak 10:16) writes that where trees blossom at different times, such as in Australia, one recites the beracha then (See Har Tzvi OC 1:118; Teshuvos Vehanhagos 1:190).
While the Kaf Hachaim (OC 226:9) writes that one can only recite the beracha upon first seeing the blossom, most poskim (Machatzis Hashekel 226; Shaar Hatziyun 226:3; Halichos Shlomo, Tefilla 2:5) write that one can recite it later if necessary.
R’ Zvi Pesach Frank (Har Tzvi OC 1:118) writes that one should not recite this beracha at night time, though the consensus of poskim (Tzitz Eliezer 12:20:6, Chazon Ovadia, Pesach 1: p11; Rivevos Ephraim 6:458:2) is that one may do so providing that one can see the blossom clearly.
The Kaf Hachaim (OC 226:4) writes that one shouldn’t recite this beracha on Shabbos as we are worried that one may come to pluck some blossom off the tree. (He also brings Kabbalistic reasons.) R’ Moshe Sternbuch (Teshuvos Vehanhagos 1:191) writes that some avoid doing so for fear of carrying out their Siddur (where there is no Eruv). Nonetheless, most poskim (Yechave Daas 1:1; Rivevos Ephraim 4:113:41) allow one to do so on Shabbos.
As most poskim hold that this beracha can be said whenever one sees the blossom, it is not considered to be a time-bound mitzva. Thus, R’ Zvi Pesach Frank (Har Tzvi OC 1:118) writes that women are obligated to recite the beracha too (See Tzitz Eliezer 12:25:5; Teshuvos Vehanhagos 1:190; Rivevos Ephraim 6:106, 6:458:2).