How to Prune broad-leaved dock?
Cut back prior to seed setting to avoid self-seeding

broad-leaved dock · Rumex obtusifolius
Also known as: bitter dock; broad dock; keddle dock; kettle dock; batter dock; butter dock
Grows naturally in waste and cultivated land, grassland and marshy places and can become a persistent garden weed
Cut back prior to seed setting to avoid self-seeding