care of day lillies

Id suggest once the flowers begin to die nip the heads of to save it wasting energy making seeds, maybe a feed of bone meal gently worked around the top soil in early Autumn otherwise Id leave them - eventually they will form a big clump & digging them all up splitting or dividing it before replanting will help then you will have extra plants to use or give away to freinds like me -I love them :-)

Once all the flowers have finished on the scapes (flowering stems) cut the entire stem away from the plant as low as you can. Don't try to pull it. They are very strong and you may damage the plant. You may find my 2 blogs 'The Hemerocallis Article' and
'The Hemerocallis Article' Part 2, of interest, posted on Ist and 2nd of July.

do i cut back stems of my lillies after they have stopped flowering or leave them to die back them selves

Well others may tell you better but Id nip of the dead flowers & later if the leaves die back then cut them down, again a bonemeal feed will help root growth over winter & next year they should be back stronger bigger better - Good luck Mrs Poppins lol