122:2 The practice is not to recite the bracha of shehechiyanu during the Three Weeks. (Some authorities consider this an additional stringency and therefore permit it on Shabbos – Mishnah Brurah 551:98.) Therefore, we do not purchase or put on new garments because this would require a person to say shehechiyanu. At a pidyon haben, one does recite shehechiyanu so as not to sour the mitzvah. One should be lenient and recite shehechiyanu over a new fruit on Shabbos (and Rosh Chodesh – Shaar HaTziyon 551:99), or even during the week if he would not find this kind of fruit after Tisha b’Av (and if the fruit won’t last until Shabbos – MB 551:101). One should not chastise his students or children during this period.
122:3 The practice is not to get one’s hair cut during the Three Weeks, not of the head, nor the beard, nor even body hair. Adults should not cut children’s hair.