Q. May I give flowers to my nonreligious grandmother for her birthday during Nine Days?
A. On question 3260 regarding one that buys flowers for home every Friday Lik’vod (in honor of) Shabbos, if he should also do so for Shabbos Chazon, (Shabbos before Tisha Beav), we wrote: “As mentioned in a question above, Shulchan Aruch (O.H. 551: 2) rules that from Rosh Chodesh Av until after Tisha Beav one should avoid a ‘Binyan Shel Simcha’ or building a structure dedicated mainly for pleasure and joy, and that includes planting flora and trees dedicated for those purposes.
Horav Shlomo Miller’s Shlit’a opinion is that although it is not exactly the same as planting new flowers, it is still better to avoid even just buying them on Shabbos Chazon.”
However, in this case due to the most important issues involved, Horav Aharon Miller’s Shlit’a opinion is that the flowers can be given.
Rabbi A. Bartfeld as advised by Horav Aharon Miller Shlit’a