Why did the stem suddenly weaken in my oriental poppy?

Question

I have an oriental poppy 'Patty's Plum' growing in new potting compost in a pot with good drainage. It sits in full sun, and I water it as needed in the recent dry weather. I purchased it from a nursery in May so this is the first season I've had it. Its lower leaves look healthy and for the past couple of weeks, the first two flowering stems have been growing and have felt quite sturdy. Yesterday, I noticed that the younger of the flowering stems has developed a weak spot that is dark brown in color, and the stem is now bent at 90 degrees (see photo). The leaves on the flowering stems also look slightly blackened at the edges (see photo). My location is the south-west UK.

Could this weakening be due to water sitting on the stem overnight and causing some tissue rot, or is there another likely another cause (can wind cause this)?

Answer 1

According to the National Gardening Association, they may need staking to keep them upright:

Oriental poppies perform poorly in regions with hot summers, and the flowers may need staking to keep from flopping over when in full bloom. The plants go dormant after blooming.

http://www.garden.org/plantguide/?q=show&id=2052

One author recommends getting compact varieties so that they don't need staking.

And the droopiness is partly why it tends to go in and out of fashion in England:

THE fortunes of plants soar and plunge in a way that would make a yo-yo dizzy. Take Oriental poppies. Ten years ago, they were scarcely to be found outside old cottage gardens, or those belonging to the horticulturally adventurous.

Gardeners were underwhelmed by their exuberant but short-lived flowers, the way they lay face-down in the mud after rain, and the tendency for the stems to swan-neck if they were not staked.

http://www.telegraph.co.uk/gardening/howtogrow/3290322/In-focus-oriental-poppy.html