Can I second everything that daintiness has just said, ive seen seeds available on internet, think there's a few different plants, orange, pink ones etc, which do we get? R cud it become to invasive?
I saw a peacock butterfly on my daffodils about a week ago, didnt think daffs attracted butterflies much, they r prob too early, i was surprised to see it, it was a warm day. Asciepias looks interesting, will look those up.
right list is huge as it depends on butterfly tbh growing over a season helps the species over a long period i moved here 4 years ago odd white butterfly now get about 20 species all through the year i find some good ones are honesty for oragne tips solidago for gatekeeper asters sedum for comma peacock and red admiral most herbs are good too as it verbena bonariensis,borage ,vipers bugloss , scaboious knap weeds sweet rocket but one that flowers all year is erysium bowles mauve .
also try different types of buddleia that flower earlier or later so flowers continuous oh forgot globe thistle and sea holly too good luck and be patient some times they dont seem to come then lots arrive
Erysium Bowles mauve.a small shrub that flowers all year! This plant next to verbena bonariensis and buddleia proved very successful last year for me.