lupins

Yes, remove the flowerheads as soon as they begin to look tatty, and you will often get a second round of flowers (albeit smaller). Leave this second lot of flowers on the plant to produce seed, which you can collect and store, or leave to let Nature do the job of creating more plants.

I wish Lupins would survive long enough to try this in my garden - I just can't grow them!

And I can't get rid of them - they keep self-seeding from elsewhere. I dig up the seedlings and give them away. They attract a lot of greenfly to our garden, too many for the birds and ladybirds to defeat.