I think that's Amaranthus tricolor but it might be some other amaranthus
It doesn't self seed here Kate, or very rarely. I'd save some and sow it next year.
Though it still looks very good, maybe keep dead heading and buy a new packet next year.
It could be a different species but looks much as Buddleia davidii to me. It's not native to the UK although it's gone wild here. Not native to Madeira either, China I think
save the seed from these Allan. Wait til they're dry and tip them into an envelope. Cool and dark for the winter, sow in spring
looks like my buddleia as well
that's not a wildflower in the UK. It's Clarkia./Godetia, whichever one of those names superseded the other.
Yes, put it up a corner and ignore it. No water except what drops from the sky. Probably better in a pot if you have clay soil but very quick draining compost
Did you keep it moist for the sake of the bedding plants? This one grows on some of my poorest, driest soil. It doesn't look great. I wouldn't worry about brown flowers, there will be more next year. Are there any live leaves left at the bottom? they're more important
i think I've sent you a PM GD but let me know if I haven't. First try from here instead of going into 'My Messages'
I don't know annuals but I can't see anything Malva like there. I thought they all had the lobed leaves