With great difficulty!

You plant them amongst shrubs and other shruby type plants. Thus the flowers are supported by the stems of the other plants.
(Btw, ours are planted in open ground and flopping over)

ditto but I have used small lengths of twigs and they have looked better. OH sugessted using thin fishing line but decided it was too fiddly.

thank you ~ i like the idea of them growing through other shrubs ~ thanks bulbaholic, but i may need to try the twigs this year. they are so pretty but just not so good when lying down!!!

I usually, when I can be bothered, prop the stems up with small stones. Trouble is that encourages snails which tend to eat the flowers as they appear.

Mine have been ravaged this year by slugs and snails! Too much rain and damp weather as they emerged.