gen2026, That's a very good question. Your asking made me wonder too? So I did a google search to see if I could find the answer. The earliest I found is 1762.
Both Flava and Lemon lily - Hemerocallis lilioasphodelus syn. flava were from 1762. I grow both.
The 1800's saw even more.
And that makes me wonder how many daylilies from the 1800's are still being grown?
I love some of the heirloom daylilies. AABACHEE is an older spider registered in 1957. BEAUTIFUL DREAMER is a yellow from 1955. Bess Ross, which I just got 2 years ago, is from 1951. Burning Daylight is from 1957. I probably have others from the 50's as well, and a bunch from the 60's and 70's. Not much earlier than the 50's, though, although I do have the Lemon Lily and H. fulva, H. fulva 'Kwanso' and H. fulva 'Flore Pleno'.
The foliage does stay pretty nice on Lemon lily. It is a beautiful little bloomer. Especially sense it blooms long before most daylilies start blooming. It has a real nice lemony fragrance too.
I Love the heirloom daylilies too. I grow a lot of them.
Looking at my list, I have quite a few earlier than the 50's. Of course I grow a lot from the 50's, 60's and 70's as well. Many of my favorites are heirloom.
These are the other pre 1950's daylilies I grow.
ORANGEMAN, another extra early bloomer was registered in 1906
AZTEC GOLD, 1936
BLACK PRINCE, 1942
PAINTED LADY, 1942
PURPLE WATERS, 1942
RED CINDERELLA, 1945
PINK SATIN, 1948
KINDLY LIGHT, 1949
BLACK MAGIC, 1949