The Shulchan Arukh (O.C. 226), based on the Gemara (Berakhot 43b), codifies the obligation of birkat ha-ilanot, to recite a berakha upon the sight of budding fruit trees during the springtime. This halakha is formulated as a requirement to recite birkat ha-ilanot upon seeing budding trees “bi-ymei Nissan” – “during the days of Nissan.”
The halakhic authorities debate the question of whether this reference to the month of Nissan should be taken literally as establishing the time-frame within which the berakha must be recited. Rav Yaakov Chagiz, in his Halakhot Ketanot (2:28), takes the Gemara’s formulation at face value, and rules that the berakha may be recited only during the month of Nissan. And thus even if a person sees a budding fruit tree earlier, during Adar, or later, during Iyar, he may not recite the berakha at that point. The Mishna Berura (226:1), however, based on earlier Acharonim, writes that the Gemara mentioned Nissan only because trees normally blossom during that month, and not to restrict the requirement to Nissan. According to this view, one may recite birkat ha-ilanot anytime he sees blossoming fruit trees, regardless of whether or not this occurs during Nissan.
This issue is discussed at length by Rav Tzvi Pesach Frank, in his Har Tzevi (O.C. 118), where he suggests qualifying the position of the Halakhot Ketanot. Rav Frank notes a passage in the Ritva’s commentary to Masekhet Rosh Hashanah (11b), where the Ritva writes that the Gemara did not intend to require reciting the berakha specifically during Nissan, but rather, the berakha is recited “in each and every place, according to when it blossoms.” The Ritva implies not that the berakha may be recited whenever one sees the blossoming of a tree, but rather during the predominant blossoming season in one’s geographic location. Rav Frank suggests explaining the ruling of the Halakhot Ketanot on this basis. In and around the Land of Israel, most blossoming generally occurs during the month of Nissan, and thus the berakha must be recited during that month. Even if one sees blossoming prior to Nissan – such as if one sees the blossoming of almond trees, which begins well before the onset of Nissan – or later in the spring, the berakha is to be recited during Nissan, the month when most blossoming occurs in most years. In other geographic locations, however, where blossoming occurs at other times, the berakha must – according to the Halakhot Ketanot – be recited during the month when most of the blossoming takes place.
Rav Frank applies this analysis to the question of whether the Halakhot Ketanot would classify the obligation of birkat ha-ilanot as a mitzvat asei she-ha’zman gerama – a time-bound obligation, from which women should therefore be exempt. At first glance, one might assume that since the berakha is limited to a particular calendar period – the month of Nissan – it falls under the category of mitzvot asei she-ha’zman gerama. Seemingly, then, according to the view that women’s exemption from time-bound mitzvot applies even to obligations enacted by Chazal, women would – in the view of the Halakhot Ketanot – be exempt from birkat ha-ilanot. However, Rav Frank dismisses this argument, in light of his analysis of the Halakhot Ketanot’s position. As we have seen, Rav Frank understood the Halakhot Ketanot as requiring reciting birkat ha-ilanot during Nissan not because it is intrinsically linked to the month of Nissan – like the obligation of shofar, for example, is intrinsically bound to the first of Tishrei – but because Nissan is when trees generally blossom in Eretz Yisrael. This requirement applies not a particular calendar date, but rather in a particular circumstance – the month when most trees blossom in one’s geographic area – and thus even according to the Halakhot Ketanot, women would be obligated to recite birkat ha-ilanot, as it does not fall under the formal category of mitzvot asei she-ha’zman gerama.