How to Prune Papaver 'Watermelon'?
Cut spent flowering stems back to the ground, unless seed heads are required. Cut back foliage as it fades in summer

Papaver 'Watermelon' · Papaver 'Watermelon'
Will thrive in most soils, as long as there is good drainage, but a moderately fertile, humus-rich soil that is not too acidic is ideal. Position in full sun and provide support, as stems can flop after heavy rain (see staking perennials)
Cut spent flowering stems back to the ground, unless seed heads are required. Cut back foliage as it fades in summer