Keichitsu / 啓蟄
It’s the term when insects and other creatures hibernated during winter time start hatching out of soil, and flowers start blooming. (Normally, it is early to mid March)
Especially, mid March is described as “Days when peach flowers are SMILING”.
As you’ve already noticed, Japanese in ancient time used the ward “笑う: SMILE (literally means smile as of today)” as meaning of flowers are “咲く: BLOOMING”.
I sometimes think we should appreciate and cherish beautiful old ways of saying.