Q. One that buys flowers for home every Friday Lik'vod (in honor of) Shabbos. Should he also do so for Shabbos Chazon, (Shabbos before Tisha Beav)?
A. As mentioned in a question 3255 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.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a