Usually Mother 's Day or 2nd Sunday in May
May 12
Lilac Sunday has been celebrated at the Arnold Arboretum since 1908. Tours of the lilacs and family activities are available from 10:00am to 3:00pm on Sunday, May 13., Lilac Sunday at Arnold Arboretum 2019 - BostonCentral, https://www.bostoncentral.com/events/lilac_sunday_arnold_arboretum/p911.php
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