How to Prune plume poppy?
Cut down to the base in late autumn

plume poppy · Macleaya cordata
Also known as: tree celandine
Grows best in a deep, moderately fertile soil that is moist but well-drained, but will tolerate most soils. It needs plenty of space and has the potential to become a nuisance on sandy soils. For best foliage, provide shelter from cold winds; like sun but tolerates partial shade
Cut down to the base in late autumn