If day lily seeds are like other seeds, the advice that I see for watering or for soaking seeds Is around 0.1% H2O2, which means diluting drugstore 3% peroxide around 32-to-1.
1.5 tsp per cup
or 1 ounce per quart
http://www.using-hydrogen-pero...
But many gardeners have told me that they often use it much stronger - like 2-4 times as storng or even stronger.
I've used the weak form (0.1%) on older salvia seeds and either they responded very well to it, or its just that, that year, I had finally learned how not to kill so many salvia seeds.