1 year ago Hydrangeas didn't get trimmed Q&A I did not trim off last year’s flowers. When can I do it? - Maureen - Comments Jo Co Master Gardener 1 year ago You didn’t mention what type of hydrangea you have. Spring blooming hydrangeas flower on old wood and should be pruned in May or June, after flowering. Pruning while dormant will reduce the flowers. You can remove selected old canes yearly from the ground to renew the shrub. Summer blooming hydrangeas flower on new wood and should be pruned February thru April. Here is a link to a handout on hydrangeas: http://www.hfrr.ksu.edu/doc1995.ashx http://www.johnson.ksu.edu/DesktopModules/ViewDocument.aspx?DocumentID=29683 Lori Johnson County Extension Master Gardener Sign in with Facebook to comment. Copyright 2014 The Kansas City Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.