How to prune alisma plantago-aquatica

Deadhead after flowering (mid to late summer); cut back foliage in autumn or late winter. Snip spent flower spikes at the base with scissors before seed sets. In autumn, cut old leaves and stems back to just above the waterline or crown.

Annually, with deadheading as needed through summer. Alisma plantago-aquatica (water plantain) requires modest maintenance. Deadhead spent flower spikes after flowering to prevent prolific self-seeding, which can make it invasive in still water. Cut back old foliage to the crown in autumn or late winter. Otherwise, this marginal aquatic needs little pruning.

Snip spent flower spikes at the base with scissors before seed sets. In autumn, cut old leaves and stems back to just above the waterline or crown.