Reprinted from SSCM:
As the Three Weeks is a period of tragedy and mourning, it is not appropriate during this time to recite the bracha of Shehechiyanu (which is an expression of thanks for reaching this time). Therefore, we avoid situations that would require the recital of this bracha.
Many Poskim allow the recital of this bracha on Shabbos.
There are many who recite Shehechiyanu upon purchasing/wearing new garments that are of great significance to the wearer (the parameters of this halacha are beyond the scope of this email) and therefore, this situation should be avoided during the Three Weeks.
However, purchasing all other clothing is permissible during the Three Weeks.
The Aruch Hashulchan writes that the minhag is to refrain from wearing new garments of great significance, even on Shabbos or in a situation where Shehechiyanu is not recited.
Purchasing any new garments is forbidden during the Nine Days
Important Numbers
