People say lots of stuff that really isn't credible...
I've heard that it's legal to grow them, just not to harvest opium from them... in truth, you would need a way larger patch than you could possibly grow from a single packet... Plus... the seeds available to us are supposed to have far less of the active ingredient compared with those grown for medicinal use...
The police aren't especially interested in raiding a cottage garden... unless you've planted marijuana...
I prefer the singles... These actually started out as doubles some 30 years ago when I originally planted them... they crossed with some single whites, and I've encouraged colours rather than petals.
As far as poppy culture?
up in South Dakota... You would probably plant in the Spring as soon as soil can be worked...
At my house? Spring plantings die with the heat, without blooming.
So... common information is to plant in the middle of October...
By experimenting, I've found that by planting additional patches each month through March, I get extended bloom time...
As far as cutting the flowers off the plant? Dumb idea. They bloom as much as they bloom... cut the flowers off and miss out on collecting seed for next year... Plus, those mature seed pods make attractive dried arrangements!
Of course... at my house, the goldfinches show up as soon as the seeds are ripe and chew up those pods... makes it hard to pick any pretty ones...