Can when bircas ha’ilanos be made (in terms of a date) and can it be made at night?
Answer:
Authorities dispute until when bircas ha-ilanos can be made, and some write that after Nissan one should only make it without Shem and Malchus (Or Le-Zion 3:6, 2). According to the Chasam Sofer (Hagahos to 227) it can be made up to a month after the beginning of Tekufas Nissan, meaning until the 7th of May.
However, most authorities write that if one still sees trees in blossom, one can recite the berachah even in Iyar (see Be’er Moshe 8:79).
If one can see clearly there’s no problem in making the berachah at night.
Best wishes.
