Are you talking about N. caerulea?
Sorry, haven't much experience starting small waterlily seeds (though it's something I want to do someday). I start lotus, viviparous tropical water lily nubs, and large-seeded lilies like Euryale in shallow, warm, oxygenated water, under bright lights and good filtration. For most of these I use a nutrient poor, sandy/silty medium for starting, with a peat-containing medium underneath for the roots to eventually grow into. I use aquaria or large tubs or stock tanks with aeration. Bright light seems to be very important. Temperature preference is dependent on species, and I look them up.
