If you cut the seedheads off too early, they don't always ripen, therefore you have no seeds. If you want to use the seeds, it's best to leave the seedheads on the plant to ripen.

I just knock them off into my hand when they're ripe and throw them in the back of the borders, otherwise they end up growing in the lawn then I have to dig 'em up! I have masses of Welsh poppies (yellow) all over the garden but if they start growing where I don't want them I just pull them out when they're tiny.

Hello, if you have the oriental poppys, Papaver which are perrenial then you can increase these by taking root cuttings and are very easy to do, seeds may be scattered at the backend which will help with germination as they go through the winters hard frosts, good drainage helps too, if you have papaver and they are looking tired and finished flowering then now is a good time to get the shears out and cut all the foliage back to ground level, in no time at all you will have a lovely clump of foliage and sometimes a second flush of flowers, all your other poppys the annuals are normally very easy to grow from seed, leave the seed heads to grow brown and then scatter in your chosen situation, if you require any seeds let me know i have many different poppys growing down on the allotments which always seed succesfully.

Thank you both for the useful information and Julien, I might just take you up on you kind offer.